Marine Drugs

12 pages, 1819 KiB

Open AccessArticle

Two New Alginate Lyases of PL7 and PL6 Families from Polysaccharide-Degrading Bacterium Formosa algae KMM 3553^T: Structure, Properties, and Products Analysis

by Alexey Belik, Artem Silchenko, Olesya Malyarenko, Anton Rasin, Marina Kiseleva, Mikhail Kusaykin and Svetlana Ermakova

Mar. Drugs 2020, 18(2), 130; https://doi.org/10.3390/md18020130 - 24 Feb 2020

Cited by 39 | Viewed by 4208

Abstract

A bifunctional alginate lyase (ALFA3) and mannuronate-specific alginate lyase (ALFA4) genes were found in the genome of polysaccharide-degrading marine bacterium Formosa algae KMM 3553^T. They were classified to PL7 and PL6 polysaccharide lyases families and expressed in E. coli. The [...] Read more.

A bifunctional alginate lyase (ALFA3) and mannuronate-specific alginate lyase (ALFA4) genes were found in the genome of polysaccharide-degrading marine bacterium Formosa algae KMM 3553^T. They were classified to PL7 and PL6 polysaccharide lyases families and expressed in E. coli. The recombinant ALFA3 appeared to be active both on mannuronate- and guluronate-enriched alginates, as well as pure sodium mannuronate. For all substrates, optimum conditions were pH 6.0 and 35 °C; Km was 0.12 ± 0.01 mg/mL, and half-inactivation time was 30 min at 42 °C. Recombinant ALFA4 was active predominately on pure sodium mannuronate, with optimum pH 8.0 and temperature 30 °C, Km was 3.01 ± 0.05 mg/mL. It was stable up to 30 °C; half-inactivation time was 1 h 40 min at 37 °C. ¹H NMR analysis showed that ALFA3 degraded mannuronate and mannuronate-guluronate blocks, while ALFA4 degraded only mannuronate blocks, producing mainly disaccharides. Products of digestion of pure sodium mannuronate by ALFA3 at 200 µg/mL inhibited anchorage-independent colony formation of human melanoma cells SK-MEL-5, SK-MEL-28, and RPMI-7951 up to 17% stronger compared to native polymannuronate. This fact supports previous data and suggests that mannuronate oligosaccharides may be useful for synergic tumor therapy. Full article

(This article belongs to the Special Issue Marine Enzymes: Sources, Biochemistry and Bioprocesses for Marine Biotechnology – II)

► Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
Optimum pH of ALFA3 when acting on different substrates. M – sodium mannuronate, MG – mannuronate-enriched sodium alginate, G – guluronate-enriched sodium alginate. Standard deviations are given. Full article ">Figure 2
Kinetic analysis of digestion of different substrates by ALFA3 (A) and final products of digestion of different substrates by ALFA4 (B). M – sodium polymannuronate, MG – mannuronate-enriched sodium alginate, G – guluronate-enriched sodium alginate. Time of reaction is given in h. Each lane was loaded with 60 µg of sample. Full article ">Figure 3
Products of action ALFA3 on mannuronate-enriched substrate precipitated by ethanol in ratios from 8.6 to 45.0% (low-molecular fraction). Numbers correspond to ethanol percentage in precipitation mixtures. Precipitation was run during 18 h at 4 °C. Full article ">Figure 4
1H NMR analysis of products after action of ALFA3 on guluronate-enriched substrate. (A) mannuronate-enriched sodium alginate, (B) total products after action of ALFA3, (C) high-molecular weight fractions after action of ALFA3, and (D) low-molecular weight fractions after action of ALFA3. Full article ">Figure 5
1H NMR analysis of action products of ALFA3 (A) and ALFA4 (B) on mannuronate-enriched substrate, as well as products of their joint action (C). M—sodium polymannuronate, MG—mannuronate-enriched sodium alginate, G—guluronate-enriched sodium alginate. Full article ">Figure 6
The effect of alginates and products of their digestion on colony formation of human cancer cells. All concentrations are 200 µg/mL. Full article ">

15 pages, 1438 KiB

Open AccessArticle

Polyketide Derivatives from Mangrove Derived Endophytic Fungus Pseudopestalotiopsis theae

by Xiaoqin Yu, Werner E. G. Müller, Dieter Meier, Rainer Kalscheuer, Zhiyong Guo, Kun Zou, Blessing O. Umeokoli, Zhen Liu and Peter Proksch

Mar. Drugs 2020, 18(2), 129; https://doi.org/10.3390/md18020129 - 23 Feb 2020

Cited by 26 | Viewed by 4463

Abstract

Chemical investigation of secondary metabolites from the endophytic fungus Pseudopestalotiopsis theae led to the isolation of eighteen new polyketide derivatives, pestalotheols I–Q (1–9) and cytosporins O–W (15–23), together with eight known analogs (10– [...] Read more.

Chemical investigation of secondary metabolites from the endophytic fungus Pseudopestalotiopsis theae led to the isolation of eighteen new polyketide derivatives, pestalotheols I–Q (1–9) and cytosporins O–W (15–23), together with eight known analogs (10–14 and 24–26). The structures of the new compounds were elucidated by HRMS and 1D and 2D NMR data, as well as by comparison with literature data. Modified Mosher’s method was applied to determine the absolute configuration of some compounds. Compound 23 showed significant cytotoxicity against the mouse lymphoma cell line L5178Y with an IC₅₀ value of 3.0 μM. Furthermore, compounds 22 and 23 showed moderate antibacterial activity against drug-resistant Acinetobacter baumannii (ATCC BAA-1605) in combination with sublethal colistin concentrations. Full article

(This article belongs to the Special Issue New Challenges in Structure Elucidation of Marine Natural Products: NMR Analyses and Other Advanced Methods)

► Show Figures

Figure 1

19 pages, 4161 KiB

Open AccessArticle

Mining the Metabolome and the Agricultural and Pharmaceutical Potential of Sea Foam-Derived Fungi

by Ernest Oppong-Danquah, Cristina Passaretti, Orazio Chianese, Martina Blümel and Deniz Tasdemir

Mar. Drugs 2020, 18(2), 128; https://doi.org/10.3390/md18020128 - 22 Feb 2020

Cited by 13 | Viewed by 6047

Abstract

Sea foam harbors a diverse range of fungal spores with biological and ecological relevance in marine environments. Fungi are known as the producers of secondary metabolites that are used in health and agricultural sectors, however the potentials of sea foam-derived fungi have remained [...] Read more.

Sea foam harbors a diverse range of fungal spores with biological and ecological relevance in marine environments. Fungi are known as the producers of secondary metabolites that are used in health and agricultural sectors, however the potentials of sea foam-derived fungi have remained unexplored. In this study, organic extracts of six foam-derived fungal isolates belonging to the genera Penicillium, Cladosporium, Emericellopsis and Plectosphaerella were investigated for their antimicrobial activity against plant and human pathogens and anticancer activity. In parallel, an untargeted metabolomics study using UPLC-QToF–MS/MS-based molecular networking (MN) was performed to unlock their chemical inventory. Penicillium strains were identified as the most prolific producers of compounds with an average of 165 parent ions per strain. In total, 49 known mycotoxins and functional metabolites were annotated to specific and ubiquitous parent ions, revealing considerable chemical diversity. This allowed the identification of putative new derivatives, such as a new analog of the antimicrobial tetrapeptide, fungisporin. Regarding bioactivity, the Penicillium sp. isolate 31.68F1B showed a strong and broad-spectrum activity against seven plant and human pathogens, with the phytopathogen Magnaporthe oryzae and the human pathogen Candida albicans being the most susceptible (IC₅₀ values 2.2 and 6.3 µg/mL, respectively). This is the first study mining the metabolome of the sea foam-derived fungi by MS/MS-based molecular networking, and assessing their biological activities against phytopathogens. Full article

(This article belongs to the Special Issue Marine Natural Products in Crop Protection)

► Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
Principal component analysis (PCA) scores plot of all six fungal extracts showing discrimination in chemical diversity. Full article ">Figure 2
(A) PCA scores plot of the three Penicillium strains (B) PCA loadings plot showing regions (blue: isolate 36.97F1C; orange: isolate 62.72F1A and grey: isolate 31.68F1B) of highly specific features among the Penicillium strains. Three metabolites each, contributing to the discrimination (displayed m/z values) of the three Penicillium strains, are highlighted in the PCA loadings plot and listed in <a href="#marinedrugs-18-00128-t002" class="html-table">Table 2</a> as examples. All other discriminatory metabolites annotated are shown in <a href="#app1-marinedrugs-18-00128" class="html-app">Table S2</a>. Full article ">Figure 3
(A) Molecular network (MN) of extracts from three Penicillium strains. Annotated compounds are displayed in <a href="#app1-marinedrugs-18-00128" class="html-app">Table S2</a>. Nodes represent parent ions detected in the crude extracts of the fungi. Nodes that are highlighted in boxes, also named in the rectangles close to them, indicate representatives of that compound molecular family (B) Venn diagram displaying specific and shared parent ions detected in the culture extracts of three Penicillium strains. Full article ">Figure 4
Cyclic tetrapeptides undergo random ring opening at each amide bond to yield linear peptides which fragment to yield nondirect sequence (NDS) ions and direct sequence (DS) ions. The first two fragments from each ring opening point (1, 2, 3 and 4) are annotated, and the sequence of the cyclo-tetrapeptide is consequently predicted. (A) MS/MS spectrum of node m/z 493.2730 annotated as fungisporin. (B) Annotated MS/MS spectrum of the putative new analog of fungisporin m/z 525.2654. V, valine; F, phenylalanine; Y, tyrosine; Y’, putatively identified as N-hydroxyl-tyrosine (as shown in <a href="#marinedrugs-18-00128-f005" class="html-fig">Figure 5</a>B) or β-hydroxyl-tyrosine. Full article ">Figure 5
(A) MN of Cladosporium sp. and Emericellopsis sp. highlighting annotated parent ions. Nodes highlighted in boxes, also named in the rectangles close to them, indicate representatives of that compound molecular family (B) Euler diagram generated from the MN showing strain specific ions and shared ions between the two strains. Full article ">Figure 6
MN of Plectosphaerella sp. highlighting annotated parent ions. Nodes highlighted in boxes, also named in the rectangles close to them, indicate representatives of that compound MF. Full article ">

14 pages, 1008 KiB

Open AccessArticle

Identification of Quorum Sensing Activators and Inhibitors in The Marine Sponge Sarcotragus spinosulus

by Kumar Saurav, Nicola Borbone, Ilia Burgsdorf, Roberta Teta, Alessia Caso, Rinat Bar-Shalom, Germana Esposito, Maya Britstein, Laura Steindler and Valeria Costantino

Mar. Drugs 2020, 18(2), 127; https://doi.org/10.3390/md18020127 - 20 Feb 2020

Cited by 17 | Viewed by 4948

Abstract

Marine sponges, a well-documented prolific source of natural products, harbor highly diverse microbial communities. Their extracts were previously shown to contain quorum sensing (QS) signal molecules of the N-acyl homoserine lactone (AHL) type, known to orchestrate bacterial gene regulation. Some bacteria and [...] Read more.

Marine sponges, a well-documented prolific source of natural products, harbor highly diverse microbial communities. Their extracts were previously shown to contain quorum sensing (QS) signal molecules of the N-acyl homoserine lactone (AHL) type, known to orchestrate bacterial gene regulation. Some bacteria and eukaryotic organisms are known to produce molecules that can interfere with QS signaling, thus affecting microbial genetic regulation and function. In the present study, we established the production of both QS signal molecules as well as QS inhibitory (QSI) molecules in the sponge species Sarcotragus spinosulus. A total of eighteen saturated acyl chain AHLs were identified along with six unsaturated acyl chain AHLs. Bioassay-guided purification led to the isolation of two brominated metabolites with QSI activity. The structures of these compounds were elucidated by comparative spectral analysis of ¹HNMR and HR-MS data and were identified as 3-bromo-4-methoxyphenethylamine (1) and 5,6-dibromo-N,N-dimethyltryptamine (2). The QSI activity of compounds 1 and 2 was evaluated using reporter gene assays for long- and short-chain AHL signals (Escherichia coli pSB1075 and E. coli pSB401, respectively). QSI activity was further confirmed by measuring dose-dependent inhibition of proteolytic activity and pyocyanin production in Pseudomonas aeruginosa PAO1. The obtained results show the coexistence of QS and QSI in S. spinosulus, a complex signal network that may mediate the orchestrated function of the microbiome within the sponge holobiont. Full article

(This article belongs to the Special Issue Quorum Quenching Agents: Exploring Quorum Sensing Interfering Strategies in Marine Bacteria for the Development of Novel Therapeutics)

► Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
Molecular phylogenetic analysis based on cytochrome oxidase gene, subunit 1 sequences. The Maximum Likelihood tree is shown, with sequences repossess in this study highlighted in bold and red. Bootstrap values derive from 1000 replications and are shown at branch nodes. Values above 50% are shown. Full article ">Figure 2
Chemical structure of compounds 1 and 2. Full article ">Figure 3
Dose-dependent effect of 1, 2 and penicillic acid (PA) on QS-dependent bioluminescence of: A) The LuxR-based reporter E. coli pSB401 induced by OXO-C6-AHL; B) The LasR-based reporter E. coli pSB1075 induced by OXO-C12-AHL. Data are expressed as SD of mean (n = 3). * P < 0.05 versus control by ANOVA followed by Bonferroni posttest. The average bioluminescence observed for the negative control is shown by a line representing the degree of luminescence when ran without any inhibitory molecule but with its cognate AHLs. Full article ">Figure 4
Dose-dependent inhibition of proteolytic activity (panel A) and pyocyanin production (panel B) by 1, 2 and penicillic acid (PA). P. aeruginosa PAO1 grown in the presence of diluting solvent was used as negative control in both experiments. Data are expressed as SD of mean (n = 3). * P < 0.05 versus control by ANOVA followed by Bonferroni posttest. Full article ">

13 pages, 2654 KiB

Open AccessArticle

Characterization of a New Chitosanase from a Marine Bacillus sp. and the Anti-Oxidant Activity of Its Hydrolysate

by Chunrui Ma, Xiao Li, Kun Yang and Shangyong Li

Mar. Drugs 2020, 18(2), 126; https://doi.org/10.3390/md18020126 - 19 Feb 2020

Cited by 28 | Viewed by 3660

Abstract

Chitooligosaccharide (COS) has been recognized to exhibit efficient anti-oxidant activity. Enzymatic hydrolysis using chitosanases can retain all the amino and hydroxyl groups of chitosan, which are necessary for its activity. In this study, a new chitosanase encoding gene, csnQ, was cloned from [...] Read more.

Chitooligosaccharide (COS) has been recognized to exhibit efficient anti-oxidant activity. Enzymatic hydrolysis using chitosanases can retain all the amino and hydroxyl groups of chitosan, which are necessary for its activity. In this study, a new chitosanase encoding gene, csnQ, was cloned from the marine Bacillus sp. Q1098 and expressed in Escherichia coli. The recombinant chitosanase, CsnQ, showed maximal activity at pH 5.31 and 60 °C. Determination of CsnQ pH-stability showed that CsnQ could retain more than 50% of its activity over a wide pH, from 3.60 to 9.80. CsnQ is an endo-type chitosanase, yielding chitodisaccharide as the main product. Additionally, in vitro and in vivo analyses indicated that chitodisaccharide possesses much more effective anti-oxidant activity than glucosamine and low molecular weight chitosan (LMW-CS) (~5 kDa). Notably, to our knowledge, this is the first evidence that chitodisaccharide is the minimal COS fragment required for free radical scavenging. Full article

(This article belongs to the Special Issue Marine Enzymes: Sources, Biochemistry and Bioprocesses for Marine Biotechnology – II)

► Show Figures

Figure 1

Figure 1
Phylogenetic analysis of CsnQ and several other reported chitosanases. Branch-related numbers are bootstrap values (confidence limits) representing the substitution frequency of each amino acid residue. Full article ">Figure 2
Sequence comparison of CsnQ with other chitosanases from GH 46 family. The BLAST 2.0 program with the function Sequence similarity searches was used. Identical amino acid residues are boxed in red, and amino acid residues above a 70% consensus are boxed in a pale pane. The hollow triangle marks the sugar-binding site. Solid triangle marks catalytic sites. Full article ">Figure 3
SDS-PAGE analysis of the recombinant CsnQ. Lane M, protein marker; Lane 1, the crude CsnQ; Lane 2, the purified CsnQ. Full article ">Figure 4
Characterization of CsnQ. (A) The optimal temperature of CsnQ; (B) The thermal-stability of CsnQ. Taking the activity of the pre-incubated CsnQ at 0 °C as 100%, the residual activity at the optimal temperature of 60 °C was detected; (C) Optimal pH for the relative activity of CsnQ was determined in the assay (pH 4.80–9.71) containing equal volumes of Britton-Robinson buffers (pH 3.60–9.80) and substrate solution [containing 0.3% (w/v) soluble chitosan, pH 6.0] at the optimal temperature; (D) The pH stability of CsnQ was analyzed by measuring the residual activity at the optimal temperature and pH after the enzyme was pretreated at +4 °C for 12 h in different pH of Britton-Robinson buffers (pH 3.60–9.80). The mean values ± standard deviations of three experiments each in 3 replicates are shown. Full article ">Figure 5
Analysis of CsnQ reaction products. (A) TLC analysis of the degradation products of chitosan by CsnQ. The reaction system contained 450 μL 0.3% (w/v) chitosan substrate (pH 6.0) and 50 μL purified CsnQ at 60 °C, and the reaction mixture were analyzed at the indicated times. Lane M: standard monomer (DP1) and chitosan oligomers (DP2–4); Lanes 0–120: enzymatic hydrolysates of chitosan incubated at 60 °C for 0, 1, 10, 30, 60 and 120 min, respectively. (B) ESI-MS analysis of end products derived from hydrolysis of chitosan by CsnQ. Full article ">Figure 6
Anti-oxidant activity of COS. (A) In vitro analysis of CsnQ anti-oxidant activity using ABTS method, the contents of GSH-Px and T-SOD were measured in (B) Caco-2, (C) CDD-18Co and (D) HTK cell types. All the results were expressed as mean values ± S.E. obtained from three separated experiments. Blank, no treatment; control, H2O2 treated group. COS-L, 100 μg/mL; COS-M, 300 μg/mL and COS-H, 500 μg/mL. All of the drugs (COS-L, COS-M, COS-H, LMW-CS, and Glucosamine) were dissolved in 50 mM Tris-HCl buffer (pH 8.0). ## p < 0.01 indicated a highly significant difference from the blank group. * p < 0.05 and ** p <0.01 indicated significant difference from the H2O2-treated group (the control group). Full article ">

11 pages, 1097 KiB

Open AccessCommunication

Bioactive Metabolites of Marine Origin Have Unusual Effects on Model Membrane Systems

by Martin Jakubec, Christian Totland, Frode Rise, Elahe Jafari Chamgordani, Britt Paulsen, Louis Maes, An Matheeussen, Lise-Lotte Gundersen and Øyvind Halskau

Mar. Drugs 2020, 18(2), 125; https://doi.org/10.3390/md18020125 - 19 Feb 2020

Cited by 1 | Viewed by 3380

Abstract

Marine sponges and soft corals have yielded novel compounds with antineoplastic and antimicrobial activities. Their mechanisms of action are poorly understood, and in most cases, little relevant experimental evidence is available on this topic. In the present study, we investigated whether agelasine D [...] Read more.

Marine sponges and soft corals have yielded novel compounds with antineoplastic and antimicrobial activities. Their mechanisms of action are poorly understood, and in most cases, little relevant experimental evidence is available on this topic. In the present study, we investigated whether agelasine D (compound 1) and three agelasine analogs (compound 2–4) as well as malonganenone J (compound 5), affect the physical properties of a simple lipid model system, consisting of dioleoylphospahtidylcholine and dioleoylphosphatidylethanolamine. The data indicated that all the tested compounds increased stored curvature elastic stress, and therefore, tend to deform the bilayer which occurs without a reduction in the packing stress of the hexagonal phase. Furthermore, lower concentrations (1%) appear to have a more pronounced effect than higher ones (5–10%). For compounds 4 and 5, this effect is also reflected in phospholipid headgroup mobility assessed using ³¹P chemical shift anisotropy (CSA) values of the lamellar phases. Among the compounds tested, compound 4 stands out with respect to its effects on the membrane model systems, which matches its efficacy against a broad spectrum of pathogens. Future work that aims to increase the pharmacological usefulness of these compounds could benefit from taking into account the compound effects on the fluid lamellar phase at low concentrations. Full article

► Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
Molecular structures of (+) Agelasine D (1), agelasine analogues (2–4), and malonganenone J (5). Full article ">Figure 2
Deconvolution and chemical shift anisotropy (CSA) parameter extraction of selected hydrated lipid samples. (A) Representative deconvolution of 31P wide line NMR data of hydrated dioleoylphosphatidylethanolamine (DOPE) at 273 K, with a 10% addition of compound 1. Individual traces represent 1—Acquired wide line spectra, 2—Sum of fitted shapes, 3—Fit of lamellar phase, 4—Fit of isotropic phase, 5—Fit of inverse hexagonal phase. (B) CSA of dioleoylphosphatidylcholine (DOPC) lamellar phase after addition of 0%, 1%, 5%, or 10% of compound 4. Dashed lines show linear fits of CSA changes with increasing temperature. (C) CSA of DOPC lamellar phase after addition of 0%, 1%, 5%, or 10% of compound 5. Dashed lines show linear fits of CSA changes with increasing temperature. Upon extracting the CSA parameters associated with the lamellar phases, it is possible to plot them as a function of temperature and additive percentage [<a href="#B53-marinedrugs-18-00125" class="html-bibr">53</a>]. Generally, and as expected, the CSA parameters fall as temperatures increase (<a href="#marinedrugs-18-00125-f002" class="html-fig">Figure 2</a>B,C). For pure DOPC at 273 K, the CSA of the 31P nuclei in their headgroups are 34 for DOPC (<a href="#marinedrugs-18-00125-f002" class="html-fig">Figure 2</a>). This value suggests a significant orientation and restriction. Only for compound 4 and 5 in DOPC, we see a significant perturbation of the CSA values. Intriguingly, the 1% addition has the strongest effect (<a href="#marinedrugs-18-00125-f002" class="html-fig">Figure 2</a>B,C). Full article ">Figure 3
Line 31P NMR traces of lipid systems doped with compounds 1–5 and controls at 273 K. Panel (A), DOPE with 1% additive; (B), DOPE doped with 10% additive; (C), DOPC doped with 1% additive; (D), DOPE doped with 10% additive at 310 K. Traces taken from temperature scans (see <a href="#app1-marinedrugs-18-00125" class="html-app">Supplementary Information</a>) run with samples at strict equilibrium. Deconvoluted spectra are in <a href="#app1-marinedrugs-18-00125" class="html-app">Supplementary Information</a>. * Signal position consistent with an inverse hexagonal phase in DOPE. Full article ">

21 pages, 4749 KiB

Open AccessArticle

Multi-Omic Profiling of Melophlus Sponges Reveals Diverse Metabolomic and Microbiome Architectures that Are Non-overlapping with Ecological Neighbors

by Ipsita Mohanty, Sheila Podell, Jason S. Biggs, Neha Garg, Eric E. Allen and Vinayak Agarwal

Mar. Drugs 2020, 18(2), 124; https://doi.org/10.3390/md18020124 - 19 Feb 2020

Cited by 22 | Viewed by 6257

Abstract

Marine sponge holobionts, defined as filter-feeding sponge hosts together with their associated microbiomes, are prolific sources of natural products. The inventory of natural products that have been isolated from marine sponges is extensive. Here, using untargeted mass spectrometry, we demonstrate that sponges harbor [...] Read more.

Marine sponge holobionts, defined as filter-feeding sponge hosts together with their associated microbiomes, are prolific sources of natural products. The inventory of natural products that have been isolated from marine sponges is extensive. Here, using untargeted mass spectrometry, we demonstrate that sponges harbor a far greater diversity of low-abundance natural products that have evaded discovery. While these low-abundance natural products may not be feasible to isolate, insights into their chemical structures can be gleaned by careful curation of mass fragmentation spectra. Sponges are also some of the most complex, multi-organismal holobiont communities in the oceans. We overlay sponge metabolomes with their microbiome structures and detailed metagenomic characterization to discover candidate gene clusters that encode production of sponge-derived natural products. The multi-omic profiling strategy for sponges that we describe here enables quantitative comparison of sponge metabolomes and microbiomes to address, among other questions, the ecological relevance of sponge natural products and for the phylochemical assignment of previously undescribed sponge identities. Full article

(This article belongs to the Special Issue Molecular Networking as a Strategy in Discovery of Marine Bioactive Compounds)

► Show Figures

Figure 1

Figure 1
Metabolomes and microbiomes of Melophlus sponges. Morphology of (A) Melophlus sarasinorum and (B) Melophlus sp. sponges collected in Apra Harbor, Guam. (C) Microbiome composition, at the phylum level, for sponge specimens used in this study. Each sample was sequenced in duplicate. (D) Relative abundances of sarasinosides and melophlin congeners among sponge specimens used in this study. Darker color denotes higher abundance. (E) Overlap of metabolomic features among sponge specimens used in this study. Features that are shared by all four Melophlus specimens used in this study are highlighted. Full article ">Figure 2
Sarasinoside chemical diversity revealed by mass spectrometry. (A) Chemical structures of sarasinoside A1 (1) and sarasinoside B1 (2). The glycosidic rings are labeled, note the difference in ring ‘C’ between the two structures. (B) Sarasinoside molecular network. The motif_451, motif_505, and motif_668 are shown in color. Subnetworks corresponding to tetra-, tri-, and diglycosylated sarasinosides are labeled. Relevance of nodes labeled A, X, and Y is described in text. (C) Distribution of nodes according to glycosylation pattern, and distribution of nodes for which chemical identities can be dereplicated (known) and for which identities are not known (unknown) according to glycosylation pattern. (D) Structural annotation of ions comprising motif_505 (left), and motif_668 (middle), and motif_451 (right). (E) Extracted ion chromatogram generated by MZmine2 demonstrating four features corresponding to m/z 1321.65. The red dashed line represents the MS1 threshold below which all features were discarded. Feature-based molecular networking (FBMN) demonstrating the clustering of the four features with other nodes corresponding to sarasinoside congeners. Full article ">Figure 3
Characterization of low-abundance sarasinoside congeners. (A) Comparison of MS2 fragmentation spectra corresponding to nodes for 1, X, and Y (as labeled in <a href="#marinedrugs-18-00124-f002" class="html-fig">Figure 2</a>B). Chemical structures for two principal fragment ions, m/z 311.27 and m/z 409.35 that are detected in the MS2 fragmentation spectra for 1 are shown. The ion m/z 455.35 for X denotes the methoxylated, dehydrogenated sterol, as compared to 1, with the 3’-OH preserved. (B) Sarasinoside molecular network in which edges corresponding to characteristic mass differences, such as hydroxylation (green), methylation (blue), and dehydrogenation (red) are highlighted. Compared to the molecular network in <a href="#marinedrugs-18-00124-f002" class="html-fig">Figure 2</a>B, singleton nodes and edges corresponding to MS2LDA motifs are omitted for clarity. Full article ">Figure 4
Sarasinoside biosynthetic potential in the M. sarasinorum metagenome. (A) Sterol biosynthetic scheme with key enzymes (in red) and intermediates (in blue). Note that 2,3-oxidosqualene can be transformed to either cycloartenol or lanosterol. Only lanosterol is relevant as a biosynthetic intermediate for the elaboration of sarasinosides. (B) All GUM_22 metagenomic scaffolds greater than 10 kb in length are displayed in grey. Colored points represent phylogenetically assigned scaffolds classified by amino acid sequence similarity of multiple predicted proteins to sequences from the GenBank nr database. (C) Tight clustering of the metagenomic contigs for the γ-proteobacterium that harbors the msb and mgb gene loci. (D) Metagenomic scaffolds bearing the mgb and msb loci. Protein products of neighboring genes, in purple, do not bear homology to sterol biosynthetic genes or sugar biosynthesis/transfer genes. Full article ">Figure 5
Other glycosylated molecules present in Melophlus metabolomes. (A) Network containing nodes for m/z 601.41 (in green) and m/z 763.46 (in blue) that correspond to mono- and diglycosylated C30 polyacetylinic natural products, respectively. (B) MS2 fragmentation spectra for m/z 601.41 (in green, top) and m/z 763.46 (in blue, bottom) demonstrating the neutral losses for one, and two hexose sugar moieties, respectively. The position of the parent ions is marked by diamonds. Two major fragment ions are detected, m/z 421.34 and m/z 439.35 that are annotated to the molecular formulae as labeled. The low-abundance fragment ions between 100 and 300 Da are characteristic of long alkyl chains, which, when fragmented, generate ions separated by methylene (14 Da) units. (C) Subnetwork containing nodes for m/z 421.34 and m/z 439.35 (in red). Progressing from m/z 439.35, connecting nodes can be annotated by rationalizing modifications, such as hydroxylation (+O, node in yellow), dehydrogenation (−2H, node in pink), and reduction (+2H, node in green). (D) Mining the MarinLit database for m/z 439.35 leads to the identification of yakushynol F as a potential structure which is supported by fragmentation pattern characteristic of long alkyl chains. Glycosylation at either, and both hydroxyls of yakushynol F will lead to products corresponding to m/z 601.41 and m/z 763.46, respectively. Full article ">Figure 6
Inventory of melophlin congeners in sponge extracts. (A) Chemical structure of isomers 3 and 4. Note the difference in methylation state at C5 between 3 and 4. A retrobiosynthetic reaction sequence is shown in which the amino acid (glycine or alanine) primary amine condenses with the activated β-keto acid (shown as the enolate tautomer) progressing to Dieckmann cyclization which will furnish the tetramate heterocyclic core structure for melophlins. (B) Molecular network for melophlin congeners. The three MS2LDA motifs are highlighted as curved connecting edges with nodes corresponding to previously known melophlin congeners shown as diamonds and those corresponding to unknown brominated congeners shown as yellow circles. (C) Structural annotation of MS2 fragment ions comprising of motif_437, motif_444, and motif_660. Note that all fragment ions observed here constitute the tetramate heterocycle. (D) Distribution of known and unknown melophlin congeners quantified from panel B. Full article ">Figure 7
Microbiome and metabolome divergence between sponge geographical neighbors. (A) Morphology of Ianthella basta (top, specimen GUM_65) and the presence of I. basta sponges on the Apra harbor seafloor (bottom). (B) Shannon diversity indices for M. sarasinorum GUM_22 and I. basta GUM_65. (C) Relative abundance heatmap for microbiome amplicon sequence variants (ASVs) at the phyla level for technical replicates of GUM_22 and GUM_65. The histogram demonstrates ASV abundances. (D) Representative polybrominated natural products detected in the I. basta metabolomes dereplicated using MarinLit. (E) Comparative two-dimensional distribution of metabolomic features mined using MZmine2 for the four Melophlus specimens used in this study (on left) against four biological replicates of I. basta (on right). Each sponge specimen was analyzed by LC/MS in duplicate. On the x-axis, on a log2 scale, is plotted the mean ratio fold-change (FC) for each metabolomic feature identified above a common MS1 abundance threshold. The y-axis represents the statistical significance p-value of the ratio fold-change for each metabolite (plotted on a log10 scale). Metabolomic features with p-value > 0.05 are colored grey. Full article ">

26 pages, 13526 KiB

Open AccessArticle

3D Chitin Scaffolds of Marine Demosponge Origin for Biomimetic Mollusk Hemolymph-Associated Biomineralization Ex-Vivo

by Marcin Wysokowski, Tomasz Machałowski, Iaroslav Petrenko, Christian Schimpf, David Rafaja, Roberta Galli, Jerzy Ziętek, Snežana Pantović, Alona Voronkina, Valentine Kovalchuk, Viatcheslav N. Ivanenko, Bert W. Hoeksema, Cristina Diaz, Yuliya Khrunyk, Allison L. Stelling, Marco Giovine, Teofil Jesionowski and Hermann Ehrlich

Mar. Drugs 2020, 18(2), 123; https://doi.org/10.3390/md18020123 - 19 Feb 2020

Cited by 38 | Viewed by 8113

Abstract

Structure-based tissue engineering requires large-scale 3D cell/tissue manufacture technologies, to produce biologically active scaffolds. Special attention is currently paid to naturally pre-designed scaffolds found in skeletons of marine sponges, which represent a renewable resource of biomaterials. Here, an innovative approach to the production [...] Read more.

Structure-based tissue engineering requires large-scale 3D cell/tissue manufacture technologies, to produce biologically active scaffolds. Special attention is currently paid to naturally pre-designed scaffolds found in skeletons of marine sponges, which represent a renewable resource of biomaterials. Here, an innovative approach to the production of mineralized scaffolds of natural origin is proposed. For the first time, a method to obtain calcium carbonate deposition ex vivo, using living mollusks hemolymph and a marine-sponge-derived template, is specifically described. For this purpose, the marine sponge Aplysin aarcheri and the terrestrial snail Cornu aspersum were selected as appropriate 3D chitinous scaffold and as hemolymph donor, respectively. The formation of calcium-based phase on the surface of chitinous matrix after its immersion into hemolymph was confirmed by Alizarin Red staining. A direct role of mollusks hemocytes is proposed in the creation of fine-tuned microenvironment necessary for calcification ex vivo. The X-ray diffraction pattern of the sample showed a high CaCO₃ amorphous content. Raman spectroscopy evidenced also a crystalline component, with spectra corresponding to biogenic calcite. This study resulted in the development of a new biomimetic product based on ex vivo synthetized ACC and calcite tightly bound to the surface of 3D sponge chitin structure. Full article

(This article belongs to the Special Issue Marine Biomaterials 2020)

► Show Figures

Figure 1

18 pages, 1191 KiB

Open AccessArticle

Impact of Light Intensity on Antioxidant Activity of Tropical Microalgae

by Noémie Coulombier, Elodie Nicolau, Loïc Le Déan, Cyril Antheaume, Thierry Jauffrais and Nicolas Lebouvier

Mar. Drugs 2020, 18(2), 122; https://doi.org/10.3390/md18020122 - 18 Feb 2020

Cited by 41 | Viewed by 5398

Abstract

Twelve microalgae species isolated in tropical lagoons of New Caledonia were screened as a new source of antioxidants. Microalgae were cultivated at two light intensities to investigate their influence on antioxidant capacity. To assess antioxidant property of microalgae extracts, four assays with different [...] Read more.

Twelve microalgae species isolated in tropical lagoons of New Caledonia were screened as a new source of antioxidants. Microalgae were cultivated at two light intensities to investigate their influence on antioxidant capacity. To assess antioxidant property of microalgae extracts, four assays with different modes of action were used: 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2’-azino-bis (3-éthylbenzothiazoline-6-sulphonique) (ABTS), oxygen radical absorbance capacity (ORAC), and thiobabituric acid reactive substances (TBARS). This screening was coupled to pigment analysis to link antioxidant activity and carotenoid content. The results showed that none of the microalgae studied can scavenge DPPH and ABTS radicals, but Chaetoceros sp., Nephroselmis sp., and Nitzschia A sp. have the capacity to scavenge peroxyl radical (ORAC) and Tetraselmis sp., Nitzschia A sp., and Nephroselmis sp. can inhibit lipid peroxidation (TBARS). Carotenoid composition is typical of the studied microalgae and highlight the siphonaxanthin, detected in Nephroselmis sp., as a pigment of interest. It was found that xanthophylls were the major contributors to the peroxyl radical scavenging capacity measured with ORAC assay, but there was no link between carotenoids and inhibition of lipid peroxidation measured with TBARS assay. In addition, the results showed that light intensity has a strong influence on antioxidant capacity of microalgae: Overall, antioxidant activities measured with ORAC assay are better in high light intensity whereas antioxidant activities measured with TBARS assay are better in low light intensity. It suggests that different antioxidant compounds production is related to light intensity. Full article

► Show Figures

Graphical abstract

13 pages, 1507 KiB

Open AccessArticle

Donghaecyclinones A–C: New Cytotoxic Rearranged Angucyclinones from a Volcanic Island-Derived Marine Streptomyces sp.

by Munhyung Bae, Joon Soo An, Seong-Heon Hong, Eun Seo Bae, Beomkoo Chung, Yun Kwon, Suckchang Hong, Ki-Bong Oh, Jongheon Shin, Sang Kook Lee and Dong-Chan Oh

Mar. Drugs 2020, 18(2), 121; https://doi.org/10.3390/md18020121 - 18 Feb 2020

Cited by 20 | Viewed by 4058

Abstract

Chemical profiling of the Streptomyces sp. strain SUD119, which was isolated from a marine sediment sample collected from a volcanic island in Korea, led to the discovery of three new metabolites: donghaecyclinones A–C (1–3). The structures of 1– [...] Read more.

Chemical profiling of the Streptomyces sp. strain SUD119, which was isolated from a marine sediment sample collected from a volcanic island in Korea, led to the discovery of three new metabolites: donghaecyclinones A–C (1–3). The structures of 1–3 were found to be rearranged, multicyclic, angucyclinone-class compounds according to nuclear magnetic resonance (NMR) and mass spectrometry (MS) analyses. The configurations of their stereogenic centers were successfully assigned using a combination of quantum mechanics–based computational methods for calculating the NMR shielding tensor (DP4 and CP3) as well as electronic circular dichroism (ECD) along with a modified version of Mosher’s method. Donghaecyclinones A–C (1–3) displayed cytotoxicity against diverse human cancer cell lines (IC₅₀: 6.7–9.6 μM for 3). Full article

(This article belongs to the Special Issue Application of Circular Dichroism to Define Stereostructures of Marine Bioactives)

► Show Figures

Figure 1

Figure 1
The structures of donghaecyclinones A–C (1–3). Full article ">Figure 2
Determination of the planar structures of donghaecyclinones A–C (1–3) based on the analysis of key COSY and HMBC correlations. Full article ">Figure 3
Key ROESY correlations of donghaecyclinone A (1). Full article ">Figure 4
Determination of the absolute configuration of donghaecyclinone A (1). (a) ΔδS-R values of the MTPA esters (1a and 1b) in DMSO-d6. (b) the simulated DP4 models of the two possible diastereomers 1c/1d (3R, 4S, 7S, and 12S/3R, 4S, 7R, and 12R) of 1. Full article ">Figure 5
Determination of the relative and absolute configurations of donghaecyclinones B and C (2 and 3). (a) The simulated CP3 models of two possible diastereomer sets 2a/3a (3R*, 4S*, and 3′S*/3R*, 4S*, and 3′R*) and 2b/3b (3R*, 4S*, and 3′R*/3R*, 4S*, and 3′S*) on 2 and 3. (b) Experimental and calculated ECD spectra of 2, 2c, and 2d. (c) Experimental and calculated ECD spectra of 3, 3c, and 3d. Full article ">Figure 6
Proposed biosynthetic pathway of donghaecyclinones A–C (1–3). Full article ">

5 pages, 169 KiB

Open AccessEditorial

Marine Glycoconjugates: Trends and Perspectives

by Vladimir I. Kalinin, Valentin A. Stonik and Natalia V. Ivanchina

Mar. Drugs 2020, 18(2), 120; https://doi.org/10.3390/md18020120 - 18 Feb 2020

Cited by 1 | Viewed by 2512

Abstract

Glycoconjugates play significant roles in biological systems and are used in medicine, for example as vaccines [...] Full article

(This article belongs to the Special Issue Marine Glycoconjugates: Trends and Perspectives)

15 pages, 2897 KiB

Open AccessArticle

Evaluation of the Antibacterial Material Production in the Fermentation of Bacillus amyloliquefaciens-9 from Whitespotted Bamboo Shark (Chiloscyllium plagiosum)

by Wenjie Zhang, Ling Wei, Rong Xu, Guodong Lin, Huijie Xin, Zhengbing Lv, Hong Qian and Hengbo Shi

Mar. Drugs 2020, 18(2), 119; https://doi.org/10.3390/md18020119 - 18 Feb 2020

Cited by 15 | Viewed by 3298

Abstract

Bacillus amyloliquefaciens-9 (GBacillus-9), which is isolated from the intestinal tract of the white-spotted bamboo shark (Chiloscyllium plagiosum), can secrete potential antibacterial materials, such as β-1,3-1,4-glucanase and some antimicrobial peptides. However, the low fermentation production has hindered the development of GBacillus-9 as [...] Read more.

Bacillus amyloliquefaciens-9 (GBacillus-9), which is isolated from the intestinal tract of the white-spotted bamboo shark (Chiloscyllium plagiosum), can secrete potential antibacterial materials, such as β-1,3-1,4-glucanase and some antimicrobial peptides. However, the low fermentation production has hindered the development of GBacillus-9 as biological additives. In this study, the Plackett–Burman design and response surface methodology were used to optimize the fermentation conditions in a shake flask to obtain a higher yield and antibacterial activity of GBacillus-9. On the basis of the data from medium screening, M9 medium was selected as the basic medium for fermentation. The data from the single-factor experiment showed that sucrose had the highest antibacterial activity among the 10 carbon sources. The Plackett–Burman design identified sucrose, NH₄Cl, and MgSO₄ as the major variables altering antibacterial activity. The optimal concentrations of these compounds to enhance antibacterial activity were assessed using the central composite design. Data showed that sucrose, NH₄Cl, and MgSO₄ had the highest antibacterial activities at concentrations of 64.8, 1.84, and 0.08 g L⁻¹, respectively. The data also showed that the optimal fermentation conditions for the antibacterial material production of GBacillus-9 were as follows: Inoculum volume of 5%, initial pH of 7.0, temperature of 36 °C, rotating speed of 180 rpm, and fermentation time of 10 h. The optimal fermentation medium and conditions achieved to improve the yield of antibacterial materials for GBacillus-9 can enhance the process of developing biological additives derived from GBacillus-9. Full article

(This article belongs to the Special Issue Anti-Microbial Compounds from Marine Sources)

► Show Figures

Figure 1

Figure 1
Effects of various media and main ingredient sources on antibacterial activity. (a) Effect of different media (nutrient agar (NA), Luria-Bertani (LB), nutrient yeast beef glucose (NYBD), M9, beef peptone yeast (BPY), yeast sucrose peptone (YSP), and yeast peptone glucose (YPG)) on the antibacterial activity of metabolites. TG1 and BS168 (representing the Gram-negative and Gram-positive bacteria, respectively) were used to detect antibacterial activity. The Y axis represents the diameter of the inhibition zone, indicating the antibacterial activity of metabolites. (b) Growth curves of GBacillus-9 in different media. Effects of (c) carbon and (d) nitrogen sources on the antibacterial activity of metabolites in M9 medium. The sources of carbon included dextrin, citric acid, mannitol, maltose, lactose, soluble starch, glucose, xylose, and sucrose. The sources of nitrogen included peptone, urea, NH4Cl, yeast extract, (NH4)2SO4, yeast extract cream, and beef cream. Full article ">Figure 2
Optimum concentrations of Sucrose (a), Na2HPO4 (b), KH2PO4 (c), NH4Cl (d), MgSO4 (e), and NaCl (f) in M9 medium. Full article ">Figure 3
Pareto chart of the standardized effects: (a) Response is TG1; (b) response is BS 168; Full article ">Figure 4
Response surface curves of the inhibition zone diameters of TG1 and BS168 by using the media cultured with GBacillus-9. (a) and (d): Interaction between sucrose and NH4Cl. (b) and (e): Interaction between sucrose and MgSO4. (c) and (f): Interaction between NH4Cl and MgSO4. The standard concentrations of Na2HPO4, KH2PO4, and NaCl used in the experiment were 8.5, 3, and 0.5 g L−1, respectively. Full article ">Figure 5
Effect of fermentation parameters ((a): Inoculation concentration, (b): pH, (c): Temperature, (d): Rotating speed, and (e): Time) on the antibacterial activity of metabolites. Full article ">Figure 6
Validation of the optimal fermentation conditions of GBacillus-9 in 20 L bioreactor. Full article ">

18 pages, 3377 KiB

Open AccessArticle

Genome Sequencing and Analysis of Thraustochytriidae sp. SZU445 Provides Novel Insights into the Polyunsaturated Fatty Acid Biosynthesis Pathway

by Xingyu Zhu, Shuangfei Li, Liangxu Liu, Siting Li, Yanqing Luo, Chuhan Lv, Boyu Wang, Christopher H. K. Cheng, Huapu Chen and Xuewei Yang

Mar. Drugs 2020, 18(2), 118; https://doi.org/10.3390/md18020118 - 18 Feb 2020

Cited by 27 | Viewed by 4542

Abstract

Thraustochytriidae sp. have broadly gained attention as a prospective resource for the production of omega-3 fatty acids production in significant quantities. In this study, the whole genome of Thraustochytriidae sp. SZU445, which produces high levels of docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA), [...] Read more.

Thraustochytriidae sp. have broadly gained attention as a prospective resource for the production of omega-3 fatty acids production in significant quantities. In this study, the whole genome of Thraustochytriidae sp. SZU445, which produces high levels of docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA), was sequenced and subjected to protein annotation. The obtained clean reads (63.55 Mb in total) were assembled into 54 contigs and 25 scaffolds, with maximum and minimum lengths of 400 and 0.0054 Mb, respectively. A total of 3513 genes (24.84%) were identified, which could be classified into six pathways and 44 pathway groups, of which 68 genes (1.93%) were involved in lipid metabolism. In the Gene Ontology database, 22,436 genes were annotated as cellular component (8579 genes, 38.24%), molecular function (5236 genes, 23.34%), and biological process (8621 genes, 38.42%). Four enzymes corresponding to the classic fatty acid synthase (FAS) pathway and three enzymes corresponding to the classic polyketide synthase (PKS) pathway were identified in Thraustochytriidae sp. SZU445. Although PKS pathway-associated dehydratase and isomerase enzymes were not detected in Thraustochytriidae sp. SZU445, a putative DHA- and DPA-specific fatty acid pathway was identified. Full article

(This article belongs to the Special Issue Genome Mining and Synthetic Biology in Marine Natural Products Discovery)

► Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
Statistical analysis of the GC content and depth correlation analysis of Thraustochytriidae sp. SZU445. The abscissa is the GC content, and the ordinate is the average depth. The scatter plot shows a shape that approximates a Poisson distribution and shows that sequencing data have low GC bias. Full article ">Figure 2
Genomic circle diagram of Thraustochytriidae sp. SZU445. From the outer to the inner rings: Genome (sorted by length), gene density (gene number in 50,000 bp nonoverlapping windows), ncRNA density (ncRNA number in 100,000 bp nonoverlapping windows), GC (GC rate in 20,000 bp nonoverlapping windows), GC_skew (GC skew in 20,000 bp nonoverlapping windows). Full article ">Figure 3
Gene length distribution of Thraustochytriidae sp. SZU445. The abscissa is the length of the gene, and the ordinate is the number of genes corresponding to the length of the gene. Full article ">Figure 4
Distribution of GO database functional annotations. The ordinate is the annotation item, and the abscissa is the number of corresponding genes. Full article ">Figure 5
Distribution of KEGG database functional annotations. The ordinate is the annotation item, and the abscissa is the number of corresponding genes. Full article ">Figure 6
The phylogenetic tree produced using the neighbor-joining method analysis. The evolutionary history was inferred using the neighbor-joining method. The optimal tree with the sum of branch length = 0.01309240 is shown. The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (1000 replicates) is shown next to the branches. The evolutionary distances were computed using the maximum composite likelihood method and are in the units of the number of base substitutions per site. The analysis involved six nucleotide sequences. Codon positions included were 1st + 2nd + 3rd + noncoding. All ambiguous positions were removed for each sequence pair. There were a total of 1739 positions in the final dataset. Evolutionary analyses were conducted in MEGA7. Full article ">Figure 7
Putative fatty acid synthase pathway of Thraustochytriidae sp. SZU445 with the classical fatty acid synthesis pathway and the polyketide synthase pathway. The enzymes colored blue are present in the classical fatty acid synthase (FAS) and polyketide synthase (PKS) pathways. The enzymes colored green are present in Thraustochytriidae sp. SZU445 and correspond to the classical FAS and PKS pathways. The enzymes colored red are isozymes of dehydrase and isomerase in the PKS pathway that exist in Thraustochytriidae sp. SZU445. Full article ">

6 pages, 176 KiB

Open AccessEditorial

Selected Papers from the Third International Symposium on Life Science

by Valentin A. Stonik

Mar. Drugs 2020, 18(2), 117; https://doi.org/10.3390/md18020117 - 18 Feb 2020

Viewed by 2113

Abstract

The search for and isolation of marine biologically active compounds, as well as relevant studies on their structure and properties are important for the adding knowledge about molecular diversity in nature and creation of medicines and other useful products on this basis [...] [...] Read more.

The search for and isolation of marine biologically active compounds, as well as relevant studies on their structure and properties are important for the adding knowledge about molecular diversity in nature and creation of medicines and other useful products on this basis [...] Full article

(This article belongs to the Special Issue Selected Papers from the 3rd International Symposium on Life Science)

15 pages, 2836 KiB

Open AccessArticle

Fucoxanthinol from the Diatom Nitzschia Laevis Ameliorates Neuroinflammatory Responses in Lipopolysaccharide-Stimulated BV-2 Microglia

by Yuelian Li, Lu Liu, Peipei Sun, Yifeng Zhang, Tao Wu, Han Sun, Ka-Wing Cheng and Feng Chen

Mar. Drugs 2020, 18(2), 116; https://doi.org/10.3390/md18020116 - 17 Feb 2020

Cited by 29 | Viewed by 3798

Abstract

In recent years, microalgae have drawn increasing attention as a valuable source of functional food ingredients. Intriguingly, Nitzschia laevis is rich in fucoxanthinol that is seldom found in natural sources. Fucoxanthinol, a marine xanthophyll carotenoid, possesses various beneficial bioactivities. Nevertheless, it’s not clear [...] Read more.

In recent years, microalgae have drawn increasing attention as a valuable source of functional food ingredients. Intriguingly, Nitzschia laevis is rich in fucoxanthinol that is seldom found in natural sources. Fucoxanthinol, a marine xanthophyll carotenoid, possesses various beneficial bioactivities. Nevertheless, it’s not clear whether fucoxanthinol could exert anti-neuroinflammatory function. In light of these premises, the aim of the present study was to investigate the anti-inflammatory role of fucoxanthinol purified from Nitzschia laevis in Lipopolysaccharide (LPS)-stimulated microglia. The results showed that pre-treatment of fucoxanthinol remarkably attenuated the expression of LPS-induced nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and the production of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), prostaglandin E2 (PGE-2), nitric oxide (NO) and reactive oxygen species (ROS) induction. Modulation mechanism studies revealed that fucoxanthinol hampered nuclear factor-kappa B (NF-κB), Akt, and mitogen-activated protein kinase (MAPK) pathways. Meanwhile, fucoxanthinol led to the enhancement of nuclear translocation of NF-E2-related factor 2 (Nrf2), and the upregulation of heme oxygenase-1 (HO-1) and NAD(P)H: quinone oxidoreductase 1 (NQO-1). Taken together, the results indicated that fucoxanthinol obtained from Nitzschia laevis had great potential as a neuroprotective agent in neuroinflammation and neurodegenerative disorders. Full article

► Show Figures

Graphical abstract

21 pages, 3053 KiB

Open AccessArticle

Understanding the Performance of a Novel Direct Compression Excipient Comprising Roller Compacted Chitin

by Deeb Abu Fara, Linda Al-Hmoud, Iyad Rashid, Babur Z. Chowdhry and Adnan Badwan

Mar. Drugs 2020, 18(2), 115; https://doi.org/10.3390/md18020115 - 17 Feb 2020

Cited by 10 | Viewed by 3873

Abstract

Chitin has been investigated in the context of finding new excipients suitable for direct compression, when subjected to roller compaction. Ball milling was concurrently carried out to compare effects from different energy or stress-inducing techniques. Samples of chitin powders (raw, processed, dried and [...] Read more.

Chitin has been investigated in the context of finding new excipients suitable for direct compression, when subjected to roller compaction. Ball milling was concurrently carried out to compare effects from different energy or stress-inducing techniques. Samples of chitin powders (raw, processed, dried and humidified) were compared for variations in morphology, X-ray diffraction patterns, densities, FT-IR, flowability, compressibility and compactibility. Results confirmed the suitability of roller compaction to convert the fluffy powder of raw chitin to a bulky material with improved flow. X-ray powder diffraction studies showed that, in contrast to the high decrease in crystallinity upon ball milling, roller compaction manifested a slight deformation in the crystal lattice. Moreover, the new excipient showed high resistance to compression, due to the high compactibility of the granules formed. This was correlated to the significant extent of plastic deformation compared to the raw and ball milled forms of chitin. On the other hand, drying and humidification of raw and processed materials presented no added value to the compressibility and compactibility of the directly compressed excipient. Finally, compacted chitin showed direct compression similarity with microcrystalline cellulose when formulated with metronidazole (200 mg) without affecting the immediate drug release action of the drug. Full article

(This article belongs to the Special Issue Marine Chitin 2019)

► Show Figures

Graphical abstract

43 pages, 4848 KiB

Open AccessReview

The Biological and Chemical Diversity of Tetramic Acid Compounds from Marine-Derived Microorganisms

by Minghua Jiang, Senhua Chen, Jing Li and Lan Liu

Mar. Drugs 2020, 18(2), 114; https://doi.org/10.3390/md18020114 - 15 Feb 2020

Cited by 48 | Viewed by 7448

Abstract

Tetramic acid (pyrrolidine-2,4-dione) compounds, isolated from a variety of marine and terrestrial organisms, have attracted considerable attention for their diverse, challenging structural complexity and promising bioactivities. In the past decade, marine-derived microorganisms have become great repositories of novel tetramic acids. Here, we discuss [...] Read more.

Tetramic acid (pyrrolidine-2,4-dione) compounds, isolated from a variety of marine and terrestrial organisms, have attracted considerable attention for their diverse, challenging structural complexity and promising bioactivities. In the past decade, marine-derived microorganisms have become great repositories of novel tetramic acids. Here, we discuss the biological activities of 277 tetramic acids of eight classifications (simple 3-acyl tetramic acids, 3-oligoenoyltetramic acids, 3-decalinoyltetramic acid, 3-spirotetramic acids, macrocyclic tetramic acids, N-acylated tetramic acids, α-cyclopiazonic acid-type tetramic acids, and other tetramic acids) from marine-derived microbes, including fungi, actinobacteria, bacteria, and cyanobacteria, as reported in 195 research studies up to 2019. Full article

► Show Figures

Figure 1

28 pages, 3233 KiB

Open AccessArticle

Synthesis and Biological Evaluation of Four New Ricinoleic Acid-Derived 1-O-alkylglycerols

by René Momha, Victor Kuete, Jean-Marie Pagès, Dieudonné Emmanuel Pegnyemb and Paul Mosset

Mar. Drugs 2020, 18(2), 113; https://doi.org/10.3390/md18020113 - 15 Feb 2020

Cited by 11 | Viewed by 3715

Abstract

A series of novel substituted 1-O-alkylglycerols (AKGs) containing methoxy (8), gem-difluoro (9), azide (10) and hydroxy (11) group at 12 position in the alkyl chain were synthesized from commercially available ricinoleic acid [...] Read more.

A series of novel substituted 1-O-alkylglycerols (AKGs) containing methoxy (8), gem-difluoro (9), azide (10) and hydroxy (11) group at 12 position in the alkyl chain were synthesized from commercially available ricinoleic acid (12). The structures of these new synthesized AKGs were established by NMR experiments as well as from the HRMS and elementary analysis data. The antimicrobial activities of the studied AKGs 8–11 were evaluated, respectively, and all compounds exhibited antimicrobial activity to different extents alone and also when combined with some commonly used antibiotics (gentamicin, tetracycline, ciprofloxacin and ampicillin). AKG 11 was viewed as a lead compound for this series as it exhibited significantly higher antimicrobial activity than compounds 8–10. Full article

(This article belongs to the Special Issue Synthesis of Marine Natural Products and Molecules Inspired by Marine Substances)

► Show Figures

Figure 1

Figure 1
Natural 1-O-alkylglycerols (AKGs) (1). Full article ">Figure 2
Synthesized AKGs 2–7, prominent components of natural shark liver oil (SLO) mixture. Full article ">Figure 3
Synthesized AKGs 8–11 from ricinoleic acid. Full article ">Figure 4
Time-effect of the studied AKGs on the growth of E. coli LMP701 when tested with the MIC of the studied samples. Full article ">Figure 5
Time-effect of the studied AKGs on the growth of E. coli LMP701 when tested with the 4× MIC of the studied samples. Full article ">Scheme 1
Synthesis of AKG 8. Reagents and conditions: (a) BF3.2MeOH, MeOH, 50 °C, 15 h, 75% of 13 and 4% of 14; (b) K2CO3, MeOH, rt, 42 h, quantitative conversion of 14 into 13; (c) MeI, NaOH, n-Bu4NBr, DMSO, rt, 18 h, 72%; (d) Red-Al, Et2O, 0 °C, 16 h, 82%; (e) MsCl, Et3N, DCM, −50 °C, 5 h, 74%; (f) KOH, n-Bu4NBr, DMSO, 35 °C, 14 h, 93%; (g) p-TsOH.H2O (0.05 equiv), MeOH/H2O (9:1), 60 °C, 5 h, 99%. Full article ">Scheme 2
Synthesis of AKG 11. Reagents and conditions: (a) 2-(bromomethyl)naphthalene, NaOH, n-Bu4NBr, DMSO, 18 h, rt; (b) ClSii-Pr3, imidazole, DMF, 48 h, rt, 61%; (c) Red-Al, Et2O, 0 °C, 5 h, 94%; (d) MsCl, Et3N, DCM, −50 °C, 2 h, 76%; (e) 18, NaH, DMF, 15 h, rt, 68%; (f) TBAF, THF, rt, 20 h, 92%; (g) p-TsOH.H2O (0.05 equiv), MeOH/H2O (9:1), 60 °C, 4 h, 84%. Full article ">Scheme 3
Synthesis of AKG 9. Reagents and conditions: (a) PCC, DCM, 1 h, rt, 68%; (b) DAST, DCM, 21 days, rt, 54%; (c) Red-Al, Et2O, 0 °C, 5 h, 77%; (d) MsCl, Et3N, DCM, −35 °C to −5 °C, 4–5 h, 69% from 26; (e) 18, 50% aqueous NaOH, n-Bu4NBr, DMSO, 40 °C, 15 h, 63%; (f) p-TsOH.H2O (0.05 equiv), MeOH/H2O (9:1), 60 °C, 5 h, 92%. Full article ">Scheme 4
Synthesis of AKG 10. Reagents and conditions: (a) MsCl, Et3N, DCM, −10 °C, 4 h, 65%; (b) NaN3, DMSO, 80 °C, 18 h, 80%; (c) Dibal, Et2O, −80 °C, 2 h, 68%; (d) NaBH4, EtOH, 0 °C, 1 h, 74%; (e) MsCl, Et3N, DCM, −50 °C, 4 h and then up to −5 °C, 59%; (f) 18, 50% aqueous NaOH, n-Bu4NBr, DMSO, 40 °C, 15 h; (g) maleic anhydride, cyclohexane, 72 h, 45 °C; (h) p-TsOH.H2O (0.05 equiv), MeOH/H2O (9:1), 60 °C, 5 h, 97%. Full article ">

22 pages, 6061 KiB

Open AccessArticle

Investigating the Antiparasitic Potential of the Marine Sesquiterpene Avarone, Its Reduced Form Avarol, and the Novel Semisynthetic Thiazinoquinone Analogue Thiazoavarone

by Concetta Imperatore, Roberto Gimmelli, Marco Persico, Marcello Casertano, Alessandra Guidi, Fulvio Saccoccia, Giovina Ruberti, Paolo Luciano, Anna Aiello, Silvia Parapini, Sibel Avunduk, Nicoletta Basilico, Caterina Fattorusso and Marialuisa Menna

Mar. Drugs 2020, 18(2), 112; https://doi.org/10.3390/md18020112 - 14 Feb 2020

Cited by 23 | Viewed by 4246

Abstract

The chemical analysis of the sponge Dysidea avara afforded the known sesquiterpene quinone avarone, along with its reduced form avarol. To further explore the role of the thiazinoquinone scaffold as an antiplasmodial, antileishmanial and antischistosomal agent, we converted the quinone avarone into the [...] Read more.

The chemical analysis of the sponge Dysidea avara afforded the known sesquiterpene quinone avarone, along with its reduced form avarol. To further explore the role of the thiazinoquinone scaffold as an antiplasmodial, antileishmanial and antischistosomal agent, we converted the quinone avarone into the thiazinoquinone derivative thiazoavarone. The semisynthetic compound, as well as the natural metabolites avarone and avarol, were pharmacologically investigated in order to assess their antiparasitic properties against sexual and asexual stages of Plasmodium falciparum, larval and adult developmental stages of Schistosoma mansoni (eggs included), and also against promastigotes and amastigotes of Leishmania infantum and Leishmania tropica. Furthermore, in depth computational studies including density functional theory (DFT) calculations were performed. A toxic semiquinone radical species which can be produced starting both from quinone- and hydroquinone-based compounds could mediate the anti-parasitic effects of the tested compounds. Full article

(This article belongs to the Special Issue Selected Papers from XVI MaNaPro and XI ECMNP)

► Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
Structures of aplidinones A, B and of thiazinoquinone derivatives. Full article ">Figure 2
Structure of avarone (1), the semisynthetic thiazoavarone (2) and avarol (3). Full article ">Figure 3
Key 1H-13C HMBC correlations of thiazoavarone (2). Full article ">Figure 4
Compounds 1–3 impair adult S. mansoni viability. Worm pairs were incubated with DMSO (vehicle) (black circle) or the indicated compounds at 50 μM (yellow triangle), or 20 μM (green, square) as described in material and methods. Phenotype analysis was recorded for 7 days and % viability represents the mean ± SEM of three independent experiments. Full article ">Figure 5
Thiazoavarone (2) impairs egg viability and maturation. Representative pictures of IVLEs treated with vehicle (DMSO) (a) or compound 2 at 5 μM (b) and 20 μM (c) for 72 h. Filled red arrows indicate viable eggs at stages III–V (intermediate/developed); filled red triangle indicate viable eggs at stages I–II (immature); red-edged arrows indicate damaged eggs at stages III–V; red-edged triangle indicate damaged eggs at stages I–II. Bar, 200 μm. Full article ">Figure 6
Density functional theory DFT conformers of compounds 1–3 superimposed by the carbon atoms of the quinone/hydroquinone ring. Carbon atoms are colored according to conformer classification (I = green, II = magenta, III = pink, IV = light blue, V = orange, and VI = Yellow); heteroatoms are colored by atom type (H = white, O = red, N = blue, S = orange). Hydrogens are omitted for sake of clarity, with the exception of those of the first methylene group of the R′ substituent, whose intramolecular distances from the nearby oxygen atom of the quinone are reported. Full article ">Figure 7
(A): DFT global minimum energy conformer (GM) structure of 1 (Q), DFT conformer I of 3 (QH2) and their semiquinone radical (QH•). (B) DFT GM structure of 2 (Q) together with its one- and two-electron reduced species QH• and QH2. Atoms possibly involved in an intramolecular radical shift are evidenced with red dashed lines. The LUMO of 1 and 2, and the HOMO of 3 are visualized using GaussView with an isosurface value of 0.02 e−/a.u.3 The NBO spin density isosurface of the QH• species is displayed using GaussView with an isosurface value of 0.01 e−/a.u.3. The blue surface (positive spin density) corresponds to an excess of α-electron density. Full article ">Scheme 1
Coupling of avarone (1) with hypotaurine via nucleophilic addition reaction. Full article ">Scheme 2
Born–Haber cycle for a generic one-electron transfer reaction in vacuo and in aqueous solution. Full article ">

13 pages, 1845 KiB

Open AccessArticle

The Marine-Derived Triterpenoid Frondoside A Inhibits Thrombus Formation

by Emmanuel Ampofo, Thomas Später, Lisa Nalbach, Michael D. Menger and Matthias W. Laschke

Mar. Drugs 2020, 18(2), 111; https://doi.org/10.3390/md18020111 - 14 Feb 2020

Cited by 8 | Viewed by 2705

Abstract

Background: The marine-derived triterpenoid frondoside A inhibits the phosphatidylinositol-3-kinase (PI3K) pathway in cancer cells. Because this pathway is also crucially involved in platelet activation, we studied the effect of frondoside A on thrombus formation. Methods: Frondoside A effects on platelet viability, surface adhesion [...] Read more.

Background: The marine-derived triterpenoid frondoside A inhibits the phosphatidylinositol-3-kinase (PI3K) pathway in cancer cells. Because this pathway is also crucially involved in platelet activation, we studied the effect of frondoside A on thrombus formation. Methods: Frondoside A effects on platelet viability, surface adhesion molecule expression, and intracellular signaling were analyzed by flow cytometry and Western blot. The effect of frondoside A was analyzed by photochemically induced thrombus formation in the mouse dorsal skinfold chamber model and by tail vein bleeding. Results: Concentrations of up to 15 µM frondoside A did not affect the viability of platelets, but reduced their surface expression of P-selectin (CD62P) and the activation of glycoprotein (GP)IIb/IIIa after agonist stimulation. Additional mechanistic analyses revealed that this was mediated by downregulation of PI3K-dependent Akt and extracellular-stimuli-responsive kinase (ERK) phosphorylation. Frondoside A significantly prolonged the complete vessel occlusion time in the mouse dorsal skinfold chamber model of photochemically induced thrombus formation and also the tail vein bleeding time when compared to vehicle-treated controls. Conclusion: Our findings demonstrated that frondoside A inhibits agonist-induced CD62P expression and activation of GPIIb/IIIa. Moreover, frondoside A suppresses thrombus formation. Therefore, this marine-derived triterpenoid may serve as a lead compound for the development of novel antithrombotic drugs. Full article

(This article belongs to the Special Issue Marine Molecules for the Treatment of Thrombosis)

► Show Figures

Figure 1

Figure 1
Effect of frondoside A on platelet viability. (A) Molecule structure of frondoside A. (B) Platelet-rich plasma (PRP) was incubated with different concentrations of frondoside A (black bars, n = 5) or vehicle (white bar, n = 5) for 30 min. Untreated PRP served as negative control (grey bar, n = 5). H2O2-treated PRP served as positive control (shaded gray bar, n = 5). Platelet viability was assessed by flow cytometry. Data are given in % of vehicle. Mean ± SD. * p < 0.05 vs. vehicle. (C) Platelet-poor plasma (PPP) was incubated with different concentrations of frondoside A (black bars, n = 5) or vehicle (white bar, n = 5) for 30 min and pTT was assessed by the determination of clotting time. Untreated PPP (gray bar, n = 5) and normal plasma (shaded gray bar, n = 5) served as negative controls. Abnormal plasma (dotted gray bar, n = 5) served as positive control. Mean ± SD. * p < 0.05 vs. vehicle. (D) PRP was incubated with frondoside A (15 µM) or vehicle for 30 min, and the expression of the PI3K subunit p110δ and α-tubulin was analyzed by Western blot. (E) Quantitative analysis of the PI3K subunit p110δ expression (black bar, frondoside A; white bar, vehicle; n = 3). Data are given in % of vehicle. Mean ± SD. Full article ">Figure 2
Effect of frondoside A on platelet activation. (A–F) PRP was incubated with different concentrations of frondoside A (black bars, n = 5) or vehicle (white bars, n = 5) for 30 min following stimulation with PAR-1-AP (A,B), ADP (C,D), or PMA (E,F) for 10 min. Surface levels of activated GPIIb/IIIa and CD62P were assessed by means of flow cytometry. Unstimulated PRP served as negative control (gray bars, n = 5). Data are given in % of vehicle. Mean ± SD. * p < 0.05 vs. vehicle. Full article ">Figure 3
Effect of frondoside A on PI3K signaling. (A–I) PRP was incubated with frondoside A (15 µM) or vehicle for 30 min followed by stimulation with PAR-1-AP (A), ADP (D), or PMA (G) for 10 min. Untreated PRP served as negative control. The expressions of pAkt, Akt, pERK1/2, ERK1/2, and α-tubulin were analyzed by means of Western blot. Quantitative analysis of pAkt/Akt expression (B,E,H) and pERK/ERK expression (C,F,I) (black bars, frondoside A; white bars, vehicle; gray bars, untreated control; n = 3) of (A), (D) and (G), respectively. Data are given in % of vehicle. Mean ± SD. * p < 0.05 vs. vehicle. Full article ">Figure 4
Effect of frondoside A on thrombus formation in vivo. (A,B) Intravital fluorescent microscopic images of a postcapillary venule within the dorsal skinfold chamber of a vehicle-treated mouse before (baseline) and after photochemically induced thrombus formation (asterisk). Blue-light epi-illumination with contrast enhancement by 5% FITC-labeled dextran 150,000 Da. Scale bar: 50 µm. (C,D) Diameter (C) and centerline RBC velocity (D) of postcapillary and collecting venules within the dorsal skinfold chamber of mice treated with frondoside A (black bars, n = 6), vehicle (white bars, n = 6) and clopidogrel (shaded gray bar, n = 6). Mean ± SD. (E) Complete occlusion time of postcapillary and collecting venules upon photochemically induced thrombus formation in dorsal skinfold chambers of mice treated with frondoside A (black bar, n = 6), vehicle (white bar, n = 6) and clopidogrel (shaded gray bar, n = 6), as assessed by intravital fluorescence microscopy. Mean ± SD. * p < 0.05 vs. vehicle. (D) Tail vein bleeding time of mice treated with frondoside A (black bar, n = 6), vehicle (white bar, n = 6) and clopidogrel (shaded gray bar, n = 6). Mean ± SD. * p < 0.05 vs. vehicle. # p < 0.05 vs. frondoside A. Full article ">

14 pages, 2158 KiB

Open AccessArticle

Antitumor Activity of Asperphenin A, a Lipopeptidyl Benzophenone from Marine-Derived Aspergillus sp. Fungus, by Inhibiting Tubulin Polymerization in Colon Cancer Cells

by Song Yi Bae, Lijuan Liao, So Hyun Park, Won Kyung Kim, Jongheon Shin and Sang Kook Lee

Mar. Drugs 2020, 18(2), 110; https://doi.org/10.3390/md18020110 - 13 Feb 2020

Cited by 23 | Viewed by 4072

Abstract

Marine-derived microorganisms are a valuable source of novel bioactive natural products. Asperphenin A is a lipopeptidyl benzophenone metabolite isolated from large-scale cultivation of marine-derived Aspergillus sp. fungus. The compound has shown potent antiproliferative activity against various cancer cells. However, the underlying mechanism of [...] Read more.

Marine-derived microorganisms are a valuable source of novel bioactive natural products. Asperphenin A is a lipopeptidyl benzophenone metabolite isolated from large-scale cultivation of marine-derived Aspergillus sp. fungus. The compound has shown potent antiproliferative activity against various cancer cells. However, the underlying mechanism of action remained to be elucidated. In this study, we demonstrated the antitumor activity and molecular mechanism of asperphenin A in human colon cancer cells for the first time. Asperphenin A inhibited the growth of colon cancer cells through G₂/M cell cycle arrest followed by apoptosis. We further discovered that asperphenin A can trigger microtubule disassembly. In addition to its effect on cell cycle, asperphenin A-induced reactive oxygen species. The compound suppressed the growth of tumors in a colon cancer xenograft model without any overt toxicity and exhibited a combination effect with irinotecan, a topoisomerase I inhibitor. Moreover, we identified the aryl ketone as a key component in the molecular structure responsible for the biological activity of asperphenin A using its synthetic derivatives. Collectively, this study has revealed the antiproliferative and antitumor mechanism of asperphenin A and suggested its possibility as a chemotherapeutic agent and lead compound with a novel structure. Full article

► Show Figures

Figure 1

Figure 1
Structures of asperphenins and synthetic derivatives: Asperphenin A (1); asperphenin B (2); cycloasperphenin A (3); cycloasperphenin B (4); 7-hydroxyasperphenin A (5); 7-epi-hydroxyasperphenin A (6); 7-hydroxyasperphenin B (7); 7-epi-hydroxyasperphenin B (8); 7, 15(S)-dihydroxyasperphenin A (9); 7,15(S)-dihydroxyasperphenin B (10); 7,15(R)-dihydroxyasperphenin B (11). Full article ">Figure 2
Effect of AspA on cell cycle progression and tubulin polymerization in RKO cells. (A,B) Cells were treated with the indicated concentrations of AspA for 48 h (A) or 5 μM of AspA for indicated times (B) and then analyzed by flow cytometry. (C,D) The levels of G2/M regulatory proteins in cells were determined after treatment with various concentrations of AspA for 48 h (C) or 5 μM of AspA over time (D) by western blot analysis. β-Actin was used as a loading control. (E) Inhibitory effect of AspA on tubulin polymerization. The tubulin assembly in the presence of vehicle or indicated compounds was analyzed by measuring the fluorescence emitted at 450 nm using 360 nm as an excitation wavelength for 60 min at 37 °C. Paclitaxel (TXL) and vinblastine (VBL) were used as reference compounds. The data are presented as means ± SD. Full article ">Figure 3
Effect of AspA on the induction of apoptosis and intracellular ROS in RKO cells. (A) Cells were treated with the indicated concentrations of AspA for 48 h. Collected cells were stained with Annexin V-FITC and PI, and analyzed by flow cytometry. (B,C) The expression of apoptosis-associated proteins was observed in cells treated with the indicated concentrations of AspA for 48 h (B) or 5 μM of AspA for the indicated times (C) by western blot analysis. β-Actin was used as a loading control. tBid, truncated Bid. (D) Cells were treated with AspA alone or with 5 mM of NAC for 24 h. The cells were stained with DCFH-DA and then analyzed by flow cytometry. Full article ">Figure 4
Effect of combined treatment with AspA and irinotecan or paclitaxel (TXL) on cell proliferation in RKO cells. (A,B) Cells were treated with the indicated concentrations of either irinotecan (A) or TXL (B) with or without AspA for 48 h. The cell proliferation was measured by SRB assay and the combination effect was determined by calculating combination index (CI) values. The data are presented as means ± SD. Full article ">Figure 5
Antitumor activity of AspA in a nude mouse xenograft model. (A) RKO xenograft-bearing nude mice were treated intraperitoneally with the indicated drugs three times per week for 21 days (n = 5 per group). For combination, 4 mg/kg of AspA and 4 mg/kg of irinotecan were administered. Tumor volumes were measured every 3–4 days. (B) Ki67 protein expression in RKO cell xenograft tumors was determined by immunohistochemical analysis. Scale bar, 100 μm. (C) The bodyweight of mice bearing RKO xenografts was measured every 3–4 days during the treatment with the indicated drugs (n = 5 per group). The error bars represent the means ± SD. * P < 0.05, ** P < 0.01, *** P < 0.005 by t-test. Full article ">

17 pages, 2432 KiB

Open AccessArticle

Identification of Prostaglandin Pathway in Dinoflagellates by Transcriptome Data Mining

by Valeria Di Dato, Adrianna Ianora and Giovanna Romano

Mar. Drugs 2020, 18(2), 109; https://doi.org/10.3390/md18020109 - 13 Feb 2020

Cited by 6 | Viewed by 3674

Abstract

Dinoflagellates, a major class of marine eukaryote microalgae composing the phytoplankton, are widely recognised as producers of a large variety of toxic molecules, particularly neurotoxins, which can also act as potent bioactive pharmacological mediators. In addition, similarly to other microalgae, they are also [...] Read more.

Dinoflagellates, a major class of marine eukaryote microalgae composing the phytoplankton, are widely recognised as producers of a large variety of toxic molecules, particularly neurotoxins, which can also act as potent bioactive pharmacological mediators. In addition, similarly to other microalgae, they are also good producers of polyunsaturated fatty acids (PUFAs), important precursors of key molecules involved in cell physiology. Among PUFA derivatives are the prostaglandins (Pgs), important physiological mediators in several physiological and pathological processes in humans, also used as “biological” drugs. Their synthesis is very expensive because of the elevated number of reaction steps required, thus the search for new Pgs production methods is of great relevance. One possibility is their extraction from microorganisms (e.g., diatoms), which have been proved to produce the same Pgs as humans. In the present study, we took advantage of the available transcriptomes for dinoflagellates in the iMicrobe database to search for the Pgs biosynthetic pathway using a bioinformatic approach. Here we show that dinoflagellates express nine Pg-metabolism related enzymes involved in both Pgs synthesis and reduction. Not all of the enzymes were expressed simultaneously in all the species analysed and their expression was influenced by culturing conditions, especially salinity of the growth medium. These results confirm the existence of a biosynthetic pathway for these important molecules in unicellular microalgae other than diatoms, suggesting a broad diffusion and conservation of the Pgs pathway, which further strengthen their importance in living organisms. Full article

(This article belongs to the Special Issue Bioinformatics of Marine Natural Products)

► Show Figures

Figure 1

22 pages, 7256 KiB

Open AccessArticle

COSMO-RS Based Prediction for Alpha-Linolenic Acid (ALA) Extraction from Microalgae Biomass Using Room Temperature Ionic Liquids (RTILs)

by Shiva Rezaei Motlagh, Razif Harun, Dayang Radiah Awang Biak, Siti Aslina Hussain, Rozita Omar and Amal A. Elgharbawy

Mar. Drugs 2020, 18(2), 108; https://doi.org/10.3390/md18020108 - 12 Feb 2020

Cited by 20 | Viewed by 4111

Abstract

One of the essential fatty acids with therapeutic impacts on human health is known to be omega-3 polyunsaturated fatty acids (PUFA). More lately, ionic liquids (ILs) have received significant attention among scientists in overcoming the disadvantages of traditional solvents in biomass lipid extraction. [...] Read more.

One of the essential fatty acids with therapeutic impacts on human health is known to be omega-3 polyunsaturated fatty acids (PUFA). More lately, ionic liquids (ILs) have received significant attention among scientists in overcoming the disadvantages of traditional solvents in biomass lipid extraction. However, the large pool of cations and anions possibly accessible will lead to a growing number of innovatively synthesized ILs. Nevertheless, the exhaustive measurement of all these systems is economically impractical. The conductive screening model for real solvents (COSMO-RS) is considered a precious approach with the availability of a few models to predict the characteristics of ILs. This work introduces the estimate of capacity values at infinite dilution for a range of ILs using COSMO-RS software as part of solid-liquid extraction. This favorable outcome presented that the capacity values of the IL molecules are extremely dependent on both anions and cations. Among the 352 combinations of cation/anion tested, short alkyl chain cations coupled with inorganic anions were found to be most efficient and therefore superior in the extraction method. Sulphate-, chloride-, and bromide-based ILs were found to have higher extraction capacities in contrast with the remainders, while propanoate revealed an extraordinary capacity when combined with ethyl-based cations. Eventually, the predicted results from COSMO-RS were validated through the experimentally calculated extraction yield of alpha-linolenic acid (ALA) compound from Nannochloropsis sp. microalgae. Three selected ILs namely [EMIM][Cl], [TMAm][Cl], and [EMPyrro][Br] were selected from COSMO-RS for empirical extraction purpose and the validation results pinpointed the good prediction capability of COSMO-RS. Full article

► Show Figures

Figure 1

11 pages, 3569 KiB

Open AccessArticle

New Discorhabdin B Dimers with Anticancer Activity from the Antarctic Deep-Sea Sponge Latrunculia biformis

by Fengjie Li, Dorte Janussen and Deniz Tasdemir

Mar. Drugs 2020, 18(2), 107; https://doi.org/10.3390/md18020107 - 11 Feb 2020

Cited by 15 | Viewed by 4026

Abstract

Latrunculia sponges represent a rich source of discorhabdin-type pyrroloiminoquinone alkaloids, a few of which comprise a dimeric structure. The anticancer-activity-guided isolation of the n-hexane subextract of the Antarctic deep-sea sponge Latrunculia biformis yielded the known compound (−)-(1R,2R,6R [...] Read more.

Latrunculia sponges represent a rich source of discorhabdin-type pyrroloiminoquinone alkaloids, a few of which comprise a dimeric structure. The anticancer-activity-guided isolation of the n-hexane subextract of the Antarctic deep-sea sponge Latrunculia biformis yielded the known compound (−)-(1R,2R,6R,8S,6’S)-discorhabdin B dimer (1) and two new derivatives, (−)-(1S,2R,6R,8S,6’S)-discorhabdin B dimer (2) and (−)-(1R,2R,6R,8S,6’S)-16’,17’-dehydrodiscorhabdin B dimer (3). The chemical structures of compounds 1–3 were elucidated by means of HR-ESIMS, NMR, [α]_D, ECD spectroscopy, and a comparison with the previously reported discorhabdin analogs. Compounds 1 and 2 showed significant in vitro anticancer activity against the human colon cancer cell line (HCT-116), with IC₅₀ values of 0.16 and 2.01 µM, respectively. Compared to monomeric discorhabdins, dimeric discorhabdins are very rare in Nature. This study adds two new discorhabdin dimers (2 and 3) to this small pyrroloiminoquinone subfamily. This is also the first report of compound 1 as a natural product and the first assessment of its in vitro anticancer activity. Full article

(This article belongs to the Special Issue Advances in Marine Alkaloids)

► Show Figures

Graphical abstract

12 pages, 2359 KiB

Open AccessArticle

A Pharmacological Comparison of Two Isomeric Nicotinic Receptor Agonists: The Marine Toxin Isoanatabine and the Tobacco Alkaloid Anatabine

by Hong Xing, Sunil Keshwah, Anne Rouchaud and William R. Kem

Mar. Drugs 2020, 18(2), 106; https://doi.org/10.3390/md18020106 - 11 Feb 2020

Cited by 15 | Viewed by 3695

Abstract

Many organisms possess “secondary” compounds to avoid consumption or to immobilize prey. While the most abundant or active compounds are initially investigated, more extensive analyses reveal other “minor” compounds with distinctive properties that may also be of biomedical and pharmaceutical significance. Here, we [...] Read more.

Many organisms possess “secondary” compounds to avoid consumption or to immobilize prey. While the most abundant or active compounds are initially investigated, more extensive analyses reveal other “minor” compounds with distinctive properties that may also be of biomedical and pharmaceutical significance. Here, we present an initial in vitro investigation of the actions of two isomeric tetrahydropyridyl ring-containing anabasine analogs: isoanatabine, an alkaloid isolated from a marine worm, and anatabine, a relatively abundant minor alkaloid in commercial tobacco plants. Both compounds have a double bond that is distal to the piperidine ring nitrogen of anabasine. Racemic isoanatabine and anatabine were synthesized and their S- and R-enantiomers were isolated by chiral high pressure liquid chromatography (HPLC). Both isoanatabines displayed higher efficacies at α4β2 nicotinic acetylcholine receptors (nAChRs) relative to the anatabines; R-isoanatabine was most potent. Radioligand binding experiments revealed similar α4β2 nAChR binding affinities for the isoanatabines, but R-anatabine affinity was twice that of S-anatabine. While the two anatabines and S-isoanatabine were highly efficacious agonists at α7 nAChRs, R-isoanatabine was only a weak partial agonist. The four compounds share an ability to stimulate both α4β2 and α7 nAChRs, a property that may be useful in developing more efficacious drugs to treat neurodegenerative and other medical disorders. Full article

(This article belongs to the Special Issue Marine Toxins Affecting Cholinergic System)

► Show Figures

Figure 1

Figure 1
Structures of the two alkaloids, tobacco anatabine and nemertine isoanatabine, compared with anabasine and another tetrahydropyridyl ring isomer, anabaseine. Anatabine and anabasine are known to largely occur as (S)-enantiomers; the possible chirality of natural isoanatabine is not yet known. Both anabaseine and anabasine have been found in marine (nemertine) worms and in ants. Full article ">Figure 2
Activation of human α4β2 neuronal nicotinic acetylcholine (nACh) receptors expressed in Xenopus oocytes. All peak responses were normalized with respect to the response of the cells to 100 μM ACh. R-Isoanatabine (Blue, ▲), S-Isoanatabine (Red, ■), R-Anatabine (Green, ⧫), S-Anatabine (Purple, ▼). SEM bars are included. Full article ">Figure 3
Activation of human α7 (right) neuronal nACh receptors expressed in Xenopus oocytes. R-Isoanatabine (Blue, ▲), S-Isoanatabine (Red, ■), R-Anatabine (Green, ⧫), S-Anatabine (Purple, ▼). All peak responses were normalized with respect to the response of the cells to 1 mM (α7) ACh. SEM values are included. Full article ">Figure 4
Competition binding assay of (S and R)-Isoanatabines (left) and (S and R)-Anatabines (right). Displacement of [3H]-cytisine from rat brain membranes. R-Isoanatabine (Blue, ▲), S-Isoanatabine (Red, ■), R-Anatabine (Green, ⧫), S-Anatabine (Purple, ▼). Each point represents the mean of 12 replicates (three experiments, identical concentrations tested in quadruplicate); SEM bars are shown. Full article ">

11 pages, 2117 KiB

Open AccessArticle

Floridoside Exhibits Antioxidant Properties by Activating HO-1 Expression via p38/ERK MAPK Pathway

by Tingting Niu, Gaoqing Fu, Jiawei Zhou, Hui Han, Juanjuan Chen, Wei Wu and Haimin Chen

Mar. Drugs 2020, 18(2), 105; https://doi.org/10.3390/md18020105 - 10 Feb 2020

Cited by 13 | Viewed by 3088

Abstract

Floridoside is a low-molecular-weight organic compound, which can be accumulated by red algae under stressful conditions to protect cells via its excellent antioxidant properties. In the present study, we investigated the antioxidant mechanism of floridoside toward human hepatocyte L-02 cells. We found that [...] Read more.

Floridoside is a low-molecular-weight organic compound, which can be accumulated by red algae under stressful conditions to protect cells via its excellent antioxidant properties. In the present study, we investigated the antioxidant mechanism of floridoside toward human hepatocyte L-02 cells. We found that floridoside had no toxicity to L-02 cells, and no reactive oxidative species were induced by it either. However, the expression of hemoxygenase-1 (HO-1) protein was up-regulated upon exposure to floridoside, and two antioxidant enzymes, superoxide dismutase (SOD) and GSH-Px, were activated by floridoside. Moreover, we investigated the pathway involved in the production of these antioxidants, p38/extracellular signal-regulated kinase (ERK) MAPK-nuclear factor-erythroid-2-related factor 2 (Nrf2) pathway. ERK1/2 and p38 phosphorylation, nuclear translocation of Nrf2, and activation of ARE luciferase activity were observed upon exposure to floridoside. siRNA interference and inhibitor treatment suppressed the HO-1 expression and the phosphorylation of ERK1/2 and p38, respectively. These results indicated that floridoside exerted its antioxidant activity by activating HO-1 expression via p38/ERK MAPK-Nrf2 pathway in human hepatocyte L-02 cells. Full article

(This article belongs to the Special Issue Marine Natural Product and Oxidative Stress)

► Show Figures

Figure 1

Figure 1
The structure of floridoside isolated from P. haitanensis. Full article ">Figure 2
Effect of floridoside on L-02 cell survival. Cells were exposed to 50, 100, and 200 μmol/L floridoside for 2 h. Data were expressed as the mean ± SD (n = 6). Full article ">Figure 3
Effect of floridoside on intracellular reactive oxygen species (ROS) production in L-02 cells. L-02 cells were incubated with 50, 100, 200, 400, and 800 μmol/L floridoside for 2 h. Intracellular ROS were detected by commercial DCFH-DA probes. Full article ">Figure 4
Effect of floridoside on superoxide dismutase (SOD) and GSH-Px enzyme activity. Cells were exposed to 50, 100, and 200 μmol/L floridoside for 2 h. Data were expressed as the mean ± SD. * p < 0.05 and ** p < 0.01, compared with controls. Full article ">Figure 5
Effect of floridoside on protein expression of HO-1 and mRNA expression of HO-1, γ-glutamyl cysteine ligase (γ-GCL), and NAD(P)H: quinine oxidoreductase 1 (NQO1) in L-02 cells. (A) HO-1 protein expression was examined by western blotting analysis. (B) Expressions of HO-1, γ-GCL, and NQO1 at the mRNA level were examined by RT-qPCR. Cells were exposed to 50, 100, and 200 μmol/L floridoside for 2 h. * p < 0.05 and ** p < 0.01, compared with controls. Full article ">Figure 6
Effect of floridoside on nuclear accumulation of nuclear factor-erythroid-2-related factor 2 (Nrf2), ARE luciferase activity, and HO-1 protein expression in L-02 cells. (A) L-02 cells were exposed to 50, 100, and 200 μmol/L floridoside for 2 h. The Nrf2 nuclear proteins were examined by western blotting analysis. (B) L-02 cells were transiently transfected with p-ARE-Luc reporter plasmid for 24 h and then exposed to 50, 100, and 200 μmol/L floridoside for 2 h. (C) Cells were transiently transfected with Nrf2 siRNA for 8 h and then exposed to 200 μmol/L floridoside for 48 h. HO-1 protein expression was determined by western blotting analysis. * p < 0.05 and ** p < 0.01, compared with controls; ## p < 0.01, compared with floridoside-alone treatment group. Full article ">Figure 7
Effect of floridoside on MAPK pathway and HO-1 protein expression in L-02 cells. (A) Cells were treated with 50, 100, and 200 μmol/L floridoside for 2 h. Whole cells lysates were prepared and analyzed by western blot. (B) L-02 cells were pretreated with 25 μmol/L PD98059 or SB203580 for 1 h, and then stimulated with 200 μmol/L floridoside for 2 h. HO-1 protein expression was determined by western blot. * p < 0.05 and ** p < 0.01, compared with control; ## p < 0.01, compared with floridoside-alone treatment group. Full article ">Figure 8
Antioxidant mechanism of floridoside in L-02 cells. Full article ">

29 pages, 13159 KiB

Open AccessArticle

Fucoidan Inhibition of Osteosarcoma Cells is Species and Molecular Weight Dependent

by Dhanak Gupta, Melissa Silva, Karolina Radziun, Diana C. Martinez, Christopher J. Hill, Julie Marshall, Vanessa Hearnden, Miguel A. Puertas-Mejia and Gwendolen C. Reilly

Mar. Drugs 2020, 18(2), 104; https://doi.org/10.3390/md18020104 - 8 Feb 2020

Cited by 27 | Viewed by 5673

Abstract

Fucoidan is a brown algae-derived polysaccharide having several biomedical applications. This study simultaneously compares the anti-cancer activities of crude fucoidans from Fucus vesiculosus and Sargassum filipendula, and effects of low (LMW, 10–50 kDa), medium (MMW, 50–100 kDa) and high (HMW, >100 kDa) [...] Read more.

Fucoidan is a brown algae-derived polysaccharide having several biomedical applications. This study simultaneously compares the anti-cancer activities of crude fucoidans from Fucus vesiculosus and Sargassum filipendula, and effects of low (LMW, 10–50 kDa), medium (MMW, 50–100 kDa) and high (HMW, >100 kDa) molecular weight fractions of S. filipendula fucoidan against osteosarcoma cells. Glucose, fucose and acid levels were lower and sulphation was higher in F. vesiculosus crude fucoidan compared to S. filipendula crude fucoidan. MMW had the highest levels of sugars, acids and sulphation among molecular weight fractions. There was a dose-dependent drop in focal adhesion formation and proliferation of cells for all fucoidan-types, but F. vesiculosus fucoidan and HMW had the strongest effects. G1-phase arrest was induced by F. vesiculosus fucoidan, MMW and HMW, however F. vesiculosus fucoidan treatment also caused accumulation in the sub-G1-phase. Mitochondrial damage occurred for all fucoidan-types, however F. vesiculosus fucoidan led to mitochondrial fragmentation. Annexin V/PI, TUNEL and cytochrome c staining confirmed stress-induced apoptosis-like cell death for F. vesiculosus fucoidan and features of stress-induced necrosis-like cell death for S. filipendula fucoidans. There was also variation in penetrability of different fucoidans inside the cell. These differences in anti-cancer activity of fucoidans are applicable for osteosarcoma treatment. Full article

► Show Figures

Graphical abstract

24 pages, 1881 KiB

Open AccessReview

Biosynthesis of Saxitoxin in Marine Dinoflagellates: An Omics Perspective

by Muhamad Afiq Akbar, Nurul Yuziana Mohd Yusof, Noor Idayu Tahir, Asmat Ahmad, Gires Usup, Fathul Karim Sahrani and Hamidun Bunawan

Mar. Drugs 2020, 18(2), 103; https://doi.org/10.3390/md18020103 - 5 Feb 2020

Cited by 38 | Viewed by 7617

Abstract

Saxitoxin is an alkaloid neurotoxin originally isolated from the clam Saxidomus giganteus in 1957. This group of neurotoxins is produced by several species of freshwater cyanobacteria and marine dinoflagellates. The saxitoxin biosynthesis pathway was described for the first time in the 1980s and, [...] Read more.

Saxitoxin is an alkaloid neurotoxin originally isolated from the clam Saxidomus giganteus in 1957. This group of neurotoxins is produced by several species of freshwater cyanobacteria and marine dinoflagellates. The saxitoxin biosynthesis pathway was described for the first time in the 1980s and, since then, it was studied in more than seven cyanobacterial genera, comprising 26 genes that form a cluster ranging from 25.7 kb to 35 kb in sequence length. Due to the complexity of the genomic landscape, saxitoxin biosynthesis in dinoflagellates remains unknown. In order to reveal and understand the dynamics of the activity in such impressive unicellular organisms with a complex genome, a strategy that can carefully engage them in a systems view is necessary. Advances in omics technology (the collective tools of biological sciences) facilitated high-throughput studies of the genome, transcriptome, proteome, and metabolome of dinoflagellates. The omics approach was utilized to address saxitoxin-producing dinoflagellates in response to environmental stresses to improve understanding of dinoflagellates gene–environment interactions. Therefore, in this review, the progress in understanding dinoflagellate saxitoxin biosynthesis using an omics approach is emphasized. Further potential applications of metabolomics and genomics to unravel novel insights into saxitoxin biosynthesis in dinoflagellates are also reviewed. Full article

(This article belongs to the Collection Bioactive Compounds from Marine Plankton)

► Show Figures

Figure 1

Figure 1
Decoding saxitoxin biosynthesis and its regulation via an omics approach. The production, release, and effect of saxitoxin by toxigenic dinoflagellates are influenced by their abiotic and biotic aquatic ecosystem components. This highly complex multi-organism and multi-stress environment within the context of saxitoxin synthesis can be grasped by the all-inclusive and high-throughput methods of omics. Full article ">Figure 2
Putative pathway for saxitoxin biosynthesis in cyanobacteria. Proposed reactions are based on bioinformatics prediction incorporated from several studies [<a href="#B28-marinedrugs-18-00103" class="html-bibr">28</a>,<a href="#B29-marinedrugs-18-00103" class="html-bibr">29</a>,<a href="#B30-marinedrugs-18-00103" class="html-bibr">30</a>]. A black box indicates a saxitoxin parent compound, and a blue box indicates selected saxitoxin analogues. Biosynthetic enzymes are highlighted in yellow circles. Full article ">Figure 3
(A) Central dogma of molecular biology describing the flow of genetic information from a double-stranded genomic DNA template to post-translationally modified proteins. In the nucleus, the double-stranded DNA template is transcribed into a single-stranded pre-messenger RNA (mRNA), which is further processed through steps of modification of the 5’ and 3’ ends, polyadenylation, removal of introns, and splicing of exons. The mature mRNA is exported to the cytoplasm for translation to an amino-acid sequence, which is folded and/or post-translationally modified and subcellularly localized as a functional protein. (B) Information of sxt molecules at the level of genomic DNA (gDNA), mRNA and protein. To date, the sxt gene cluster was successfully identified only in cyanobacteria species [<a href="#B28-marinedrugs-18-00103" class="html-bibr">28</a>]. However, through transcriptomic analysis, several numbers of expressed mRNA were detected from several dinoflagellate species, as described in <a href="#marinedrugs-18-00103-t002" class="html-table">Table 2</a>. Based on proteomic analysis, nine proteins encoded by sxt genes of A. catanella were identified as described in <a href="#sec5-marinedrugs-18-00103" class="html-sec">Section 5</a>. Full article ">

16 pages, 4423 KiB

Open AccessArticle

A Truncated Galectin-3 Isolated from Skin Mucus of Atlantic Salmon Salmo salar Binds to and Modulates the Proteome of the Gram-Negative Bacteria Moritella viscosa

by Deepti Manjari Patel, Yoichiro Kitani, Kjetil Korsnes, Martin Haugmo Iversen and Monica Fengsrud Brinchmann

Mar. Drugs 2020, 18(2), 102; https://doi.org/10.3390/md18020102 - 4 Feb 2020

Cited by 12 | Viewed by 4575

Abstract

The mucus of fish skin plays a vital role in innate immune defense. Some mucus proteins have the potential to incapacitate pathogens and/or inhibit their passage through the skin. In this study the aim was to isolate and characterize galectin(s), β-galactosides binding proteins, [...] Read more.

The mucus of fish skin plays a vital role in innate immune defense. Some mucus proteins have the potential to incapacitate pathogens and/or inhibit their passage through the skin. In this study the aim was to isolate and characterize galectin(s), β-galactosides binding proteins, present in skin mucus. A novel short form of galectin-3 was isolated from Atlantic salmon skin mucus by α-lactose agarose based affinity chromatography followed by Sephadex G-15 gel filtration. Mass spectrometric analysis showed that the isolated protein was the C-terminal half of galectin-3 (galectin-3C). Galectin-3C showed calcium independent and lactose inhabitable hemagglutination, and agglutinated the Gram-negative pathogenic bacteria Moritella viscosa. Galectin-3 mRNA was highly expressed in skin and gill, followed by muscle, hindgut, spleen, stomach, foregut, head kidney, and liver. Moritella viscosa incubated with galectin-3C had a modified proteome. Proteins with changed abundance included multidrug transporter and three ribosomal proteins L7/12, S2, and S13. Overall, this study shows the isolation and characterization of a novel galectin-3 short form involved in pathogen recognition and modulation, and hence in immune defense of Atlantic salmon. Full article

(This article belongs to the Special Issue Chemical Defense in Marine Organisms)

► Show Figures

Figure 1

18 pages, 552 KiB

Open AccessArticle

Nutritional Profiling and the Value of Processing By-Products from Gilthead Sea Bream (Sparus aurata)

by Mirian Pateiro, Paulo E. S. Munekata, Rubén Domínguez, Min Wang, Francisco J. Barba, Roberto Bermúdez and José M. Lorenzo

Mar. Drugs 2020, 18(2), 101; https://doi.org/10.3390/md18020101 - 4 Feb 2020

Cited by 78 | Viewed by 6563

Abstract

Fish processing industries generate a large volume of discards. In order to fulfil with the principles of a sustainable circular economy, it is necessary to maintain aquaculture by-products in the food chain through the production of high-value biomolecules that can be used as [...] Read more.

Fish processing industries generate a large volume of discards. In order to fulfil with the principles of a sustainable circular economy, it is necessary to maintain aquaculture by-products in the food chain through the production of high-value biomolecules that can be used as novel ingredients. In this study, we try to give value to the gilthead sea bream by-products, evaluating the composition and the nutritional value of the muscle and six discards commonly obtained from the fish processing industry (fishbone, gills, guts, heads, liver, and skin), which represent ≈ 61% of the whole fish. Significant differences were detected among muscle and by-products for fatty acid and amino acid profile, as well as mineral content. The discards studied were rich in protein (10%–25%), showing skin and fishbone to have the highest contents. The amino acid profile reflected the high quality of its protein, with 41%–49% being essential amino acids—lysine, leucine, and arginine were the most abundant amino acids. Guts, liver, and skin were the fattiest by-products (25%–35%). High contents of polyunsaturated fatty acids (PUFAs) (31%–34%), n-3 fatty acids (12%–14%), and eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) (6%–8%) characterized these discards. The head displayed by far the highest ash content (9.14%), which was reflected in the mineral content, especially in calcium and phosphorous. These results revealed that gilthead sea bream by-products can be used as source of value-added products such as protein, oils, and mineral supplements. Full article

(This article belongs to the Special Issue Aquaculture Wastes and By-products as Source of High Added Value Compounds: Extraction, and Health Aspects)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Mar. Drugs, Volume 18, Issue 2 (February 2020) – 61 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI