Molecules

14 pages, 4295 KiB

Open AccessArticle

Biophysical Screens Identify Fragments That Bind to the Viral DNA-Binding Proteins EBNA1 and LANA

by Troy E. Messick, Lois Tolvinski, Edward R. Zartler, Anna Moberg, Åsa Frostell, Garry R. Smith, Allen B. Reitz and Paul M. Lieberman

Molecules 2020, 25(7), 1760; https://doi.org/10.3390/molecules25071760 - 10 Apr 2020

Cited by 12 | Viewed by 4881

Abstract

The human gamma-herpesviruses Epstein–Barr virus (EBV) (HHV-4) and Kaposi’s sarcoma-associated herpesvirus (KSHV) (HHV-8) are responsible for a number of diseases, including various types of cancer. Epstein–Barr nuclear antigen 1 (EBNA1) from EBV and latency-associated nuclear antigen (LANA) from KSHV are viral-encoded DNA-binding proteins [...] Read more.

The human gamma-herpesviruses Epstein–Barr virus (EBV) (HHV-4) and Kaposi’s sarcoma-associated herpesvirus (KSHV) (HHV-8) are responsible for a number of diseases, including various types of cancer. Epstein–Barr nuclear antigen 1 (EBNA1) from EBV and latency-associated nuclear antigen (LANA) from KSHV are viral-encoded DNA-binding proteins that are essential for the replication and maintenance of their respective viral genomes during latent, oncogenic infection. As such, EBNA1 and LANA are attractive targets for the development of small-molecule inhibitors. To this end, we performed a biophysical screen of EBNA1 and LANA using a fragment library by saturation transfer difference (STD)–NMR spectroscopy and surface plasmon resonance (SPR). We identified and validated a number of unique fragment hits that bind to EBNA1 or LANA. We also determined the high-resolution crystal structure of one fragment bound to EBNA1. Results from this screening cascade provide new chemical starting points for the further development of potent inhibitors for this class of viral proteins. Full article

(This article belongs to the Special Issue Fragment Based Drug Discovery)

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Graphical abstract
Full article ">Figure 1
Fragment screening strategy to identify fragments that bind Epstein–Barr nuclear antigen 1 (EBNA1) and KSHV latency-associated nuclear antigen (LANA). STD–NMR, saturation transfer difference–NMR; SPR, surface plasmon resonance. Full article ">Figure 2
Validated fragment hits from the NMR-STD screen. (A) Structures of the validated EBNA1 fragment hits. (B) Structures of the validated LANA fragment hits. Full article ">Figure 2 Cont.
Validated fragment hits from the NMR-STD screen. (A) Structures of the validated EBNA1 fragment hits. (B) Structures of the validated LANA fragment hits. Full article ">Figure 3
Validated fragment hits from the SPR screen. (A) Structures of the top 11 fragments that bind with the highest affinity to EBNA1. (B) Bar graph showing the binding affinities of the top EBNA1 fragments. Green bars are SPR-only fragment hits. Red bars are overlapping hits from the STD–NMR screen. Blue bars are initial hits from the STD–NMR screen that were not subsequently validated. Error bars (fitting error) show assay robustness, typically approximately, or below, 25% variation. (C) Structures of the top 11 fragments that bind with the highest affinity to LANA. (D) Bar graph showing the binding affinities of the top EBNA1 fragments. Colors and error bars are as described in (B). Full article ">Figure 3 Cont.
Validated fragment hits from the SPR screen. (A) Structures of the top 11 fragments that bind with the highest affinity to EBNA1. (B) Bar graph showing the binding affinities of the top EBNA1 fragments. Green bars are SPR-only fragment hits. Red bars are overlapping hits from the STD–NMR screen. Blue bars are initial hits from the STD–NMR screen that were not subsequently validated. Error bars (fitting error) show assay robustness, typically approximately, or below, 25% variation. (C) Structures of the top 11 fragments that bind with the highest affinity to LANA. (D) Bar graph showing the binding affinities of the top EBNA1 fragments. Colors and error bars are as described in (B). Full article ">Figure 4
High-resolution crystal structure of EBNA1 bound to AC37287. (A) 2Fo–Fc electron density map of AC37287 (green). The map was contoured at 1.0 σ. (B) Electrostatic surface representation of AC37287 bound to EBNA1. (C) Cartoon and stick representation showing hydrogen bonding interaction between D519 and AC37287. (D) Superposition of DNA structure on the crystal structure of AC37287 bound to EBNA1. Full article ">Figure 5
An analysis of the fragments from the screen. Full article ">

13 pages, 1214 KiB

Open AccessArticle

Ultrasonically-Assisted and Conventional Extraction from Erodium Glaucophyllum Roots Using Ethanol:Water Mixtures: Phenolic Characterization, Antioxidant, and Anti-Inflammatory Activities

by Francisco J. Barba, Cristina Alcántara, Radhia Abdelkebir, Christine Bäuerl, Gaspar Pérez-Martínez, Jose M. Lorenzo, María Carmen Collado and Jose V. García-Pérez

Molecules 2020, 25(7), 1759; https://doi.org/10.3390/molecules25071759 - 10 Apr 2020

Cited by 10 | Viewed by 3227

Abstract

The paper presents experimental results concerning the ultrasonically-assisted extraction of bioactive compounds from Erodium glaucophyllum roots. A comparison with conventional methodology is presented, and thereby the phytochemical composition and the antioxidant and anti-inflammatory activities of extracts are evaluated. The phenolic profile of Erodium [...] Read more.

The paper presents experimental results concerning the ultrasonically-assisted extraction of bioactive compounds from Erodium glaucophyllum roots. A comparison with conventional methodology is presented, and thereby the phytochemical composition and the antioxidant and anti-inflammatory activities of extracts are evaluated. The phenolic profile of Erodium extracts was analyzed by TOF–LC–MS–MS. The identification of phenolic compounds revealed that the major component was (+)-gallocatechin in the aqueous extracts obtained for the different extraction methodologies. The highest quantity of phenolic compounds and antioxidant capacity was found in the hydroethanolic extract obtained by conventional extraction (29.22–25.50 mg GAE/g DM; 21.174 mM Trolox equivalent). The highest content of carotenoids, varying from 0.035 to 0.114 mg/g dry matter, was reached by ultrasonic-assisted extraction. Furthermore, Erodium extracts showed a potent inhibition of the inflammatory reaction by means of the inhibition of tumor necrosis factor-alpha (TNF-α). The extracts obtained when ultrasound extraction was combined with ethanol:water (50:50, v/v) presented the greatest inhibition (92%). Full article

(This article belongs to the Special Issue Extraction, Purification and Application of Antioxidants from Food Matrices, Wastes and By-Products)

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18 pages, 7326 KiB

Open AccessReview

Tri(boryl)alkanes and Tri(boryl)alkenes: The Versatile Reagents

by Oriol Salvadó and Elena Fernández

Molecules 2020, 25(7), 1758; https://doi.org/10.3390/molecules25071758 - 10 Apr 2020

Cited by 26 | Viewed by 5097

Abstract

The interest of organoboron chemistry in organic synthesis is growing, together with the development of new and versatile polyborated reagents. Here, the preparation of 1,1,1-tri(boryl)alkanes, 1,2,3-tri(boryl)alkanes, 1,1,2-tri(boryl)alkanes, as well as 1,1,2-tri(boryl)alkenes as suitable and accessible polyborated systems is demonstrated as being easily applied [...] Read more.

The interest of organoboron chemistry in organic synthesis is growing, together with the development of new and versatile polyborated reagents. Here, the preparation of 1,1,1-tri(boryl)alkanes, 1,2,3-tri(boryl)alkanes, 1,1,2-tri(boryl)alkanes, as well as 1,1,2-tri(boryl)alkenes as suitable and accessible polyborated systems is demonstrated as being easily applied in the construction of new carbon-carbon and carbon-heteroatom bonds. Synthetic procedures and limitations have been collected to demonstrate the powerful strategies to construct selective molecules, taking advantages of the easy transformation of carbon-boron bond in multiple functionalities, under the total control of chemo- and stereoselectivity. Full article

(This article belongs to the Special Issue Boron in Catalysis and Materials Chemistry: A Themed Issue in Honor of Professor Todd B. Marder on the Occasion of His 65th Birthday)

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25 pages, 10213 KiB

Open AccessReview

Molecular and Cellular Mechanisms of Cytotoxic Activity of Vanadium Compounds against Cancer Cells

by Szymon Kowalski, Dariusz Wyrzykowski and Iwona Inkielewicz-Stępniak

Molecules 2020, 25(7), 1757; https://doi.org/10.3390/molecules25071757 - 10 Apr 2020

Cited by 55 | Viewed by 5113

Abstract

Discovering that metals are essential for the structure and function of biomolecules has given a completely new perspective on the role of metal ions in living organisms. Nowadays, the design and synthesis of new metal-based compounds, as well as metal ion binding components, [...] Read more.

Discovering that metals are essential for the structure and function of biomolecules has given a completely new perspective on the role of metal ions in living organisms. Nowadays, the design and synthesis of new metal-based compounds, as well as metal ion binding components, for the treatment of human diseases is one of the main aims of bioinorganic chemistry. One of the areas in vanadium-based compound research is their potential anticancer activity. In this review, we summarize recent molecular and cellular mechanisms in the cytotoxic activity of many different synthetic vanadium complexes as well as inorganic salts. Such mechanisms shall include DNA binding, oxidative stress, cell cycle regulation and programed cell death. We focus mainly on cellular studies involving many type of cancer cell lines trying to highlight some new significant advances. Full article

(This article belongs to the Special Issue Advances in Anticancer Drug Discovery)

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22 pages, 1371 KiB

Open AccessReview

How Computational Chemistry and Drug Delivery Techniques Can Support the Development of New Anticancer Drugs

by Mariangela Garofalo, Giovanni Grazioso, Andrea Cavalli and Jacopo Sgrignani

Molecules 2020, 25(7), 1756; https://doi.org/10.3390/molecules25071756 - 10 Apr 2020

Cited by 27 | Viewed by 6331

Abstract

The early and late development of new anticancer drugs, small molecules or peptides can be slowed down by some issues such as poor selectivity for the target or poor ADME properties. Computer-aided drug design (CADD) and target drug delivery (TDD) techniques, although apparently [...] Read more.

The early and late development of new anticancer drugs, small molecules or peptides can be slowed down by some issues such as poor selectivity for the target or poor ADME properties. Computer-aided drug design (CADD) and target drug delivery (TDD) techniques, although apparently far from each other, are two research fields that can give a significant contribution to overcome these problems. Their combination may provide mechanistic understanding resulting in a synergy that makes possible the rational design of novel anticancer based therapies. Herein, we aim to discuss selected applications, some also from our research experience, in the fields of anticancer small organic drugs and peptides. Full article

(This article belongs to the Special Issue Peptides and Small Molecules as Anti-Cancer Agents)

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11 pages, 1289 KiB

Open AccessArticle

Sensitive Detection of Nucleic Acids Using Subzyme Feedback Cascades

by Nicole Hasick, Andrea Lawrence, Radhika Ramadas and Alison Todd

Molecules 2020, 25(7), 1755; https://doi.org/10.3390/molecules25071755 - 10 Apr 2020

Cited by 6 | Viewed by 3615

Abstract

The development of Subzymes demonstrates how the catalytic activity of DNAzymes can be controlled for detecting nucleic acids; however, Subzymes alone lack the sensitivity required to detect low target concentrations. To improve sensitivity, we developed a feedback system using a pair of cross-catalytic [...] Read more.

The development of Subzymes demonstrates how the catalytic activity of DNAzymes can be controlled for detecting nucleic acids; however, Subzymes alone lack the sensitivity required to detect low target concentrations. To improve sensitivity, we developed a feedback system using a pair of cross-catalytic Subzymes. These were individually tethered to microparticles (MP) and separated by a porous membrane rendering them unable to interact. In the presence of a target, active PlexZymes^® cleave a first Subzyme, which separates a first DNAzyme from its MP, allowing the DNAzyme to migrate through the membrane, where it can cleave a second Subzyme. This releases a second DNAzyme which can now migrate through the membrane and cleave more of the first Subzyme, thus initiating a cross-catalytic cascade. Activated DNAzymes can additionally cleave fluorescent substrates, generating a signal, and thereby, indicating the presence of the target. The method detected 1 fM of DNA homologous to the ompA gene of Chlamydia trachomatis within 30 min, demonstrating a 10,000-fold increase in sensitivity over PlexZyme detection alone. The Subzyme cascade is universal and can be triggered by any target by modifying the target sensing arms of the PlexZymes. Further, it is isothermal, protein-enzyme-free and shows great potential for rapid and affordable biomarker detection. Full article

(This article belongs to the Special Issue Advances in Catalytic DNA)

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Figure 1
(A) Schema illustrating the concept of Subzyme pairs capable of cross-catalysis. Subzymes are depicted attached to microparticles (MP). Subzyme 1-MP comprises DNAzyme B linked to Substrate A which is cleavable by DNAzyme A of Subzyme 2-MP. Subzyme 2-MP comprises DNAzyme A linked to Substrate B which is cleavable by DNAzyme B of Subzyme 1-MP. (B) A cross-catalytic feedback cascade in which PMBs and Subzyme-MPs are used to amplify signal following detection of a DNA target. Reactions contain Subzyme 1-MP, Subzyme 2-MP inside a PMB and partzymes for the chosen DNA target. In the presence of the target, the partzymes align and form an initiating PlexZyme which cleaves Substrate A within Subzyme 1-MP separating DNAzyme B from the MP. This allows DNAzyme B to migrate through the PMB, where it can cleave Substrate B within Subzyme 2-MP, thus separating DNAzyme A from the MP. DNAzyme A is now free to migrate from the PMB into solution, where it can cleave Substrate A within Subzyme 1-MP and initiate the cascade. After a period of incubation, the supernatant containing the free DNAzymes can be transferred to another reaction chamber containing the signaling substrate. The fluorescence which is generated following the separation of the fluorophore (F) and the quencher (Q) by DNAzyme cleavage can be measured to indicate the presence or absence of target DNA. Full article ">Figure 2
All data represent the average of two replicates. (A) Results from various rounds of Subzyme cross-catalysis. The product of an initial Subzyme-MP reaction was manually transferred through a series of reaction chambers containing alternating Subzyme-MPs for a total of seven rounds. The amount of active released DNAzyme was measured in separate reactions which contained labelled substrates after 1 (purple), 3 (green), 5 (blue) and 7 (red) rounds of incubation. Results are presented as normalized Relative Fluorescence Units (RFU) which is the fluorescence of no target controls (NTC) subtracted from the fluorescence of reactions containing target. (B) The results of an assay in which Subzyme-MPs are spatially confined within the boundaries of PMBs. Curves reflect substrate cleavage following incubation of PMB reactions containing (red line), or lacking (black line), initiating DNAzyme. Results are shown in raw RFU for 2.8 µm MP size and 0.8 µm polycarbonate PMB. (C) Results of a 30 min Subzyme feedback reaction using PMBs according to the schema presented in <a href="#molecules-25-01755-f001" class="html-fig">Figure 1</a>B. Results are plotted as normalized fluorescence following a 20 min PMB incubation step and a 10 min fluorescence detection step. Reactions contain (1) C. trachomatis TNA (target), (2) 10 fM ompA target, (3) 2 fM ompA target, (4) 1 fM ompA target, (5) nuclease free water (NTC), (6) 1 nM PPIA off-target, (7) 1 nM p273 off-target and (8) Hu gDNA (off-target). Normalized fluorescence values were obtained for each reaction by subtracting the RFU at 0 min from the RFU at 10 min of incubation with fluorescent substrate. Full article ">Figure 3
Results of three different Subzyme feedback reactions, (detailed in <a href="#molecules-25-01755-f001" class="html-fig">Figure 1</a>B), where each reaction uses the same pair of cross-catalytic Subzymes, but each employs a different PlexZyme for detecting a different DNA target. Results are plotted as normalized fluorescence following a 20 min PMB incubation step and a 5 min fluorescence detection step by subtracting the RFU at 0 min from the RFU at 5 min. All data represent the average of two replicates. Results are shown for assays designed to detect oligonucleotide targets homologous to (A) bacterial OXA gene, (B) bacterial Bla-KPC gene and (C) human TFRC gene as well as detection of the TFRC gene present in human genomic DNA. Full article ">

13 pages, 15225 KiB

Open AccessArticle

One-Pot Iridium Catalyzed C–H Borylation/Sonogashira Cross-Coupling: Access to Borylated Aryl Alkynes

by Ghayoor A. Chotana, Jose R. Montero Bastidas, Susanne L. Miller, Milton R. Smith III and Robert E. Maleczka, Jr.

Molecules 2020, 25(7), 1754; https://doi.org/10.3390/molecules25071754 - 10 Apr 2020

Cited by 6 | Viewed by 5121

Abstract

Borylated aryl alkynes have been synthesized via one-pot iridium catalyzed C–H borylation (CHB)/Sonogashira cross-coupling of aryl bromides. Direct borylation of aryl alkynes encountered problems related to the reactivity of the alkyne under CHB conditions. However, tolerance of aryl bromides to CHB made possible [...] Read more.

Borylated aryl alkynes have been synthesized via one-pot iridium catalyzed C–H borylation (CHB)/Sonogashira cross-coupling of aryl bromides. Direct borylation of aryl alkynes encountered problems related to the reactivity of the alkyne under CHB conditions. However, tolerance of aryl bromides to CHB made possible a subsequent Sonogashira cross-coupling to access the desired borylated aryl alkynes. Full article

(This article belongs to the Special Issue Advances in Cross-Coupling Reactions)

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16 pages, 4139 KiB

Open AccessArticle

In Silico Screening for Novel Leucine Aminopeptidase Inhibitors with 3,4-Dihydroisoquinoline Scaffold

by Joanna Ziemska, Jolanta Solecka and Małgorzata Jarończyk

Molecules 2020, 25(7), 1753; https://doi.org/10.3390/molecules25071753 - 10 Apr 2020

Cited by 8 | Viewed by 4734

Abstract

Cancers are the leading cause of deaths worldwide. In 2018, an estimated 18.1 million new cancer cases and 9.6 million cancer-related deaths occurred globally. Several previous studies have shown that the enzyme, leucine aminopeptidase is involved in pathological conditions such as cancer. On [...] Read more.

Cancers are the leading cause of deaths worldwide. In 2018, an estimated 18.1 million new cancer cases and 9.6 million cancer-related deaths occurred globally. Several previous studies have shown that the enzyme, leucine aminopeptidase is involved in pathological conditions such as cancer. On the basis of the knowledge that isoquinoline alkaloids have antiproliferative activity and inhibitory activity towards leucine aminopeptidase, the present study was conducted a study which involved database search, virtual screening, and design of new potential leucine aminopeptidase inhibitors with a scaffold based on 3,4-dihydroisoquinoline. These compounds were then filtered through Lipinski’s “rule of five,” and 25 081 of them were then subjected to molecular docking. Next, three-dimensional quantitative structure-activity relationship (3D-QSAR) study was performed for the selected group of compounds with the best binding score results. The developed model, calculated by leave-one-out method, showed acceptable predictive and descriptive capability as represented by standard statistical parameters r² (0.997) and q² (0.717). Further, 35 compounds were identified to have an excellent predictive reliability. Finally, nine selected compounds were evaluated for drug-likeness and different pharmacokinetics parameters such as absorption, distribution, metabolism, excretion, and toxicity. Our methodology suggested that compounds with 3,4-dihydroisoquinoline moiety were potentially active in inhibiting leucine aminopeptidase and could be used for further in-depth in vitro and in vivo studies. Full article

(This article belongs to the Special Issue Structure-Based Design of Biologically Active Compounds)

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(a) chemical structure of diethyl 6,8-dibenzyloxy-3,4-dihydroisoquinoline-3,3-dicarboxylate and (b) chemical structure of the 3,4-dihydroisoquinoline scaffold. Full article ">Figure 2
Chemical structure of the starter ligand, diethyl 6,8-dibenzyloxy-3,4-dihydroiso- quinoline-3,3-dicarboxylate, with selected substituents for replacement. Full article ">Figure 3
Interactions of the selected compounds with the best binding score values with amino acid residues and zinc ions in the leucine aminopeptidase (LAP) binding pocket. (a) 4-hydroxy-1-methyl-5-nitroso-6-{[1-(propan-2-yl)-3,4-dihydroisoquinolin-7-yl]amino}pyrimidin-2(1H)-one (score value of −51; ZINC database); (b) 4-hydroxy-5-[(6-hydroxy-3,4-dihydroisoquinolin-7-yl)oxy]-5-oxopentanoic acid (score value of −43.8; ZINC database); (c) 1,3-dioxo-4-(ethoxymethylene)-3,4-dihydroisoquinoline-2(1H)-carboxylic acid (score value of −51.72, PubChem); and (d) 1,4-dihydro-1-cyclopropyl-4-oxo-6-hydroxy-7-[3,4-dihydroisoquinoline-2(1H)-yl]-8-methylquinoline-3-carboxylic acid (score value of −42.93, PubChem). Full article ">Figure 4
(a) interactions of LAP active site residues with the compound {[6,8-(dibenzyloxy)-3-(ethoxycarbonyl)-3,4-dihydroisoquinolin-3-yl]oxy}acetic acid with the best docking score (–38.66). (b) interactions of LAP active site residues with the compound {[6,8-(dibenzyloxy)-3-(ethoxycarbonyl)-3,4-dihydroisoquinolin-3-yl]oxy}acetic acid in comparison to docking pose of diethyl 6,8-dibenzyloxy-3,4,-dihydroisoquinoline-3,3-dicarboxylate (shown in cyan). Full article ">Figure 5
Compounds after docking with Lead Finder are placed similarly to the pose of leucine in the binding site of leucine aminopeptidase; leucine (cyan) is shown. Full article ">Figure 6
Schematic representation of the used workflow. Full article ">Figure 7
Radar plots of compounds 1–9. The pink area is a suitable physicochemical space for oral bioavailability. Lipophilicity (LIPO): −0.7 < XLOGP3 < 5.0; SIZE: 150 g/mol < MW < 500 g/mol; polarity (POLAR): 20 Å2 < topological polar surface area (TPSA) < 130 Å2; and insolubility (INSOLU): 0 < LogS < 6; INSATU (insaturation): 0.25 < fraction of carbons in sp3 hybridization < 1; FLEX (flexibility): 0 < number of rotatable bonds < 9. The radar plots were obtained using the SwissADME web tool [<a href="#B36-molecules-25-01753" class="html-bibr">36</a>]. Full article ">Figure 8
BOILED-Egg plot of compounds 1–9 with excellent description of the three-dimensional quantitative structure-activity relationship (3D-QSAR) model and the best ICM score values. Points located in the BOILED-Egg yolk (yellow) represent molecules predicted to passively permeate through the blood-brain barrier (BBB), whereas points in the egg white are predicted to be passively absorbed by the gastrointestinal tract (HIA). Blue dots (PGP+) indicate the molecules expected to be effluated from the central nervous system (CNS) by P-glycoprotein, whereas the red ones (PGP-) indicate the molecules predicted not to be effluated from the CNS by P-glycoprotein. Full article ">

22 pages, 1608 KiB

Open AccessReview

Recent Advances in the Application of Antibacterial Complexes Using Essential Oils

by Tae Jin Cho, Sun Min Park, Hary Yu, Go Hun Seo, Hye Won Kim, Sun Ae Kim and Min Suk Rhee

Molecules 2020, 25(7), 1752; https://doi.org/10.3390/molecules25071752 - 10 Apr 2020

Cited by 47 | Viewed by 6418

Abstract

Although antibacterial spectrum of essential oils (EOs) has been analyzed along with consumers’ needs on natural biocides, singular treatments generally require high concentration of EOs and long-term exposures to eliminate target bacteria. To overcome these limitations, antibacterial complex has been developed and this [...] Read more.

Although antibacterial spectrum of essential oils (EOs) has been analyzed along with consumers’ needs on natural biocides, singular treatments generally require high concentration of EOs and long-term exposures to eliminate target bacteria. To overcome these limitations, antibacterial complex has been developed and this review analyzed previous reports regarding the combined antibacterial effects of EOs. Since unexpectable combined effects (synergism or antagonism) can be derived from the treatment of antibacterial complex, synergistic and antagonistic combinations have been identified to improve the treatment efficiency and to avoid the overestimation of bactericidal efficacy, respectively. Although antibacterial mechanism of EOs is not yet clearly revealed, mode of action regarding synergistic effects especially for the elimination of pathogens by using low quantity of EOs with short-term exposure was reported. Whereas comprehensive analysis on previous literatures for EO-based disinfectant products implies that the composition of constituents in antibacterial complexes is variable and thus analyzing the impact of constituting substances (e.g., surfactant, emulsifier) on antibacterial effects is further needed. This review provides practical information regarding advances in the EO-based combined treatment technologies and highlights the importance of following researches on the interaction of constituents in antibacterial complex to clarify the mechanisms of antibacterial synergism and/or antagonism. Full article

(This article belongs to the Special Issue Essential Oils as Antimicrobial and Anti-infectious Agents II)

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17 pages, 2775 KiB

Open AccessArticle

Arylaminopropanone Derivatives as Potential Cholinesterase Inhibitors: Synthesis, Docking Study and Biological Evaluation

by Anna Hudcová, Aleš Kroutil, Renata Kubínová, Adriana D. Garro, Lucas J. Gutierrez, Daniel Enriz, Michal Oravec and Jozef Csöllei

Molecules 2020, 25(7), 1751; https://doi.org/10.3390/molecules25071751 - 10 Apr 2020

Cited by 5 | Viewed by 3097

Abstract

Neurodegenerative diseases in which the decrease of the acetylcholine is observed are growing worldwide. In the present study, a series of new arylaminopropanone derivatives with N-phenylcarbamate moiety (1–16) were prepared as potential acetylcholinesterase and butyrylcholinesterase inhibitors. In vitro enzyme assays [...] Read more.

Neurodegenerative diseases in which the decrease of the acetylcholine is observed are growing worldwide. In the present study, a series of new arylaminopropanone derivatives with N-phenylcarbamate moiety (1–16) were prepared as potential acetylcholinesterase and butyrylcholinesterase inhibitors. In vitro enzyme assays were performed; the results are expressed as a percentage of inhibition and the IC₅₀ values. The inhibitory activities were compared with reference drugs galantamine and rivastigmine showing piperidine derivatives (1–3) as the most potent. A possible mechanism of action for these compounds was determined from a molecular modelling study by using combined techniques of docking, molecular dynamics simulations and quantum mechanics calculations. Full article

(This article belongs to the Section Medicinal Chemistry)

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Full article ">Figure 1
Spatial view of the compounds bonded in the binding pocket of AChE (PDB code: 1DX6). Compounds 3 (green) and 6 (light blue) are superimposed on galantamine (magenta). Some amino acids in the active site are shown in this figure for reference. The poses of compounds shown in <a href="#molecules-25-01751-f001" class="html-fig">Figure 1</a> were obtained from the Molecular Dynamics (MD) simulations. Residue of Ser200 cannot be observed in this figure because it is located exactly behind the position of the compounds. Full article ">Figure 2
Histograms of interaction energies partitioned with respect to the AChE amino acids in complex with galantamine (a), compounds 3 (b), 5 (c) and 6 (d). The x-axis denotes the residue number of AChE, and the y-axis denotes the interaction energy between the compounds and specific residue. The negative values and positive values are favorable or unfavorable to binding, respectively. Full article ">Figure 3
Molecular graph obtained for the non-covalent interactions between the main residues of AChE with galantamine (orange color). The structure of this complex was obtained from molecular dynamics simulations. The elements of the electron density topology are shown. The bond paths connecting the nuclei are represented in pink sticks and the bond critical points are shown as red spheres. Full article ">Figure 4
Molecular graph of the non-covalent interactions between the main residues of AChE with (a) compound 3 (light blue sticks) and (b) compound 6 (yellow sticks). The elements of the electron density topology are shown. The bond paths connecting the nuclei are represented in pink sticks and the bond critical points are shown as red spheres. Full article ">Scheme 1
Synthesis of intermediates 1a–4a and target compounds 1–16, reaction conditions. Full article ">

14 pages, 3963 KiB

Open AccessArticle

Characterization of ¹⁸F-PM-PBB3 (¹⁸F-APN-1607) Uptake in the rTg4510 Mouse Model of Tauopathy

by Chi-Chang Weng, Ing-Tsung Hsiao, Qing-Fang Yang, Cheng-Hsiang Yao, Chin-Yin Tai, Meng-Fang Wu, Tzu-Chen Yen, Ming-Kuei Jang and Kun-Ju Lin

Molecules 2020, 25(7), 1750; https://doi.org/10.3390/molecules25071750 - 10 Apr 2020

Cited by 32 | Viewed by 5384

Abstract

Misfolding, aggregation, and cerebral accumulation of tau deposits are hallmark features of Alzheimer’s disease. Positron emission tomography study of tau can facilitate the development of anti-tau treatment. Here, we investigated a novel tau tracer ¹⁸F-PM-PBB3 (¹⁸F-APN-1607) in a mouse model [...] Read more.

Misfolding, aggregation, and cerebral accumulation of tau deposits are hallmark features of Alzheimer’s disease. Positron emission tomography study of tau can facilitate the development of anti-tau treatment. Here, we investigated a novel tau tracer ¹⁸F-PM-PBB3 (¹⁸F-APN-1607) in a mouse model of tauopathy. Dynamic PET scans were collected in groups of rTg4510 transgenic mice at 2–11 months of age. Associations between distribution volume ratios (DVR) and standardized uptake value ratios (SUVR) with cerebellum reference were used to determine the optimal scanning time and uptake pattern for each age. Immunohistochemistry staining of neurofibrillary tangles and autoradiography study was performed for ex vivo validation. An SUVR 40–70 min was most consistently correlated with DVR and was used in further analyses. Significant increased ¹⁸F-PM-PBB3 uptake in the brain cortex was found in six-month-old mice (+28.9%, p < 0.05), and increased further in the nine-month-old group (+38.8%, p < 0.01). The trend of increased SUVR value remained evident in the hippocampus and striatum regions except for cortex where uptake becomes slightly reduced in 11-month-old animals (+37.3%, p < 0.05). Radioactivity distributions from autoradiography correlate well to the presence of human tau (HT7 antibody) and hyperphosphorylated tau (antibody AT8) from the immunohistochemistry study of the adjacent brain sections. These findings supported that the 40–70 min ¹⁸F-PM-PBB3 PET scan with SUVR measurement can detect significantly increased tau deposits in a living rTg4510 transgenic mouse models as early as six-months-old. The result exhibited promising dynamic imaging capability of this novel tau tracer, and the above image characteristics should be considered in the design of longitudinal preclinical tau image studies. Full article

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Figure 1
Mean regional standardized uptake value ratios (SUVR) time–activity curve of (A) cortex, (B) hippocampus, and (C) striatum, and (D) midbrain for each age group in the dynamic PET imaging acquisition studies. CX: cortex, HIP: hippocampus, MB: midbrain, STR: striatum, CB: cerebellum. Full article ">Figure 2
Representative 18F-PM-PBB3 PET images of different animal groups. Full article ">Figure 3
The r2 value and slope of the regression between the distribution volume ratios (DVR) and the standardized uptake value ratio (SUVR) measured at various time intervals in (A) cortex, (B) hippocampus, (C) striatum, and (D) midbrain. Correlation between DVR to SUVR at the time interval between 40–70 min post-injection for all age groups in (E) cortex, (F) hippocampus, (G) striatum, and (H) midbrain. Full article ">Figure 4
The scatter plots of regional 18F-PM-PBB3 standardized uptake value ratio (SUVR) across all age groups for regions of (A) cortex, (B) hippocampus, (C) striatum, and (D) midbrain using cerebellum as the reference region. CX: cortex, HIP: hippocampus, MB: midbrain, STR: striatum, CB: cerebellum. Full article ">Figure 5
Correlations of 18F-PM-PBB3 radioactivity distribution with tau immunohistochemical study in 6-mo-old rTg5410 mouse brain sections. (A) Representative photograph of the sagittal brain section and its autoradiography. (B) Quantitative measurement of radioactivity in different brain regions of the rTg4510 mouse. (C) Neocortical/hippocampal human tau (HT7 antibody) and hyperphosphorylated tau (antibody AT8) immunofluorescent on sagittal brain sections at the level adjacent to the autoradiography study. (CX: cortex, STR: striatum, HIP: hippocampus, MB: midbrain, CB: cerebellum.). Full article ">Figure 6
The chemical structure of 18F-PM-PBB3 (18F-APN-1607) (A) and its automatic radiosynthesis procedure scheme (B). Full article ">Figure 7
Representative VOIs from the T2 template MR image used for PET image quantification analysis. Full article ">

15 pages, 756 KiB

Open AccessArticle

Phenolic Composition of the Leaves of Pyrola rotundifolia L. and Their Antioxidant and Cytotoxic Activity

by Katarzyna Szewczyk, Anna Bogucka-Kocka, Natalia Vorobets, Anna Grzywa-Celińska and Sebastian Granica

Molecules 2020, 25(7), 1749; https://doi.org/10.3390/molecules25071749 - 10 Apr 2020

Cited by 17 | Viewed by 3674

Abstract

The leaves of Pyrola rotundifolia L. were extracted in the mixed solvent of methanol/acetone/water (2:2:1, v/v/v) and investigated for their phytochemical analysis and biological activity. Total phenolic and flavonoid contents were determined spectrophotometrically. A high content of phenols [...] Read more.

The leaves of Pyrola rotundifolia L. were extracted in the mixed solvent of methanol/acetone/water (2:2:1, v/v/v) and investigated for their phytochemical analysis and biological activity. Total phenolic and flavonoid contents were determined spectrophotometrically. A high content of phenols (208.35 mg GAE/g of dry extract), flavonoids (38.90 mg QE/g of dry extract) and gallotannins (722.91 GAE/g of dry extract) was obtained. Ultra-high performance liquid chromatography diode array detector tandem mass spectrometry (UHPLC–DAD–MS) allowed for the detection of 23 major peaks at 254 nm. The extract was analyzed for its antioxidant capacity using 2,2-diphenyl-1-picryl-hydrazyl (DPPH^•) and 2,2′-azinobis[3-ethylbenzthiazoline]-6-sulfonic acid (ABTS^•+) radical scavenging, metal chelating power and β-carotene-linoleic acid bleaching assays. The examined extract showed moderate radical scavenging and chelating activity, and good inhibiting ability of linoleic acid oxidation (EC₅₀ = 0.05 mg/mL) in comparison to standards. The cytotoxic effect in increasing concentration on five types of leukemic cell lines was also investigated using trypan blue vital staining. It was found that the analyzed extract induced the apoptosis of all the tested cell lines. Our findings suggest that the leaves of P. rotundifolia are a source of valuable compounds providing protection against oxidative damage, hence their use in traditional medicine is justified. Full article

(This article belongs to the Special Issue Chromatographic Science of Natural Products)

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26 pages, 2621 KiB

Open AccessFeature PaperArticle

Dual P-Glycoprotein and CA XII Inhibitors: A New Strategy to Reverse the P-gp Mediated Multidrug Resistance (MDR) in Cancer Cells

by Elisabetta Teodori, Laura Braconi, Silvia Bua, Andrea Lapucci, Gianluca Bartolucci, Dina Manetti, Maria Novella Romanelli, Silvia Dei, Claudiu T. Supuran and Marcella Coronnello

Molecules 2020, 25(7), 1748; https://doi.org/10.3390/molecules25071748 - 10 Apr 2020

Cited by 32 | Viewed by 3788

Abstract

A new series of N,N-bis(alkanol)amine aryl diesters was synthesized and studied as dual P-glycoprotein (P-gp) and carbonic anhydrase XII inhibitors (CA XII). These hybrids should be able to synergistically overcome P-gp mediated multidrug resistance (MDR) in cancer cells. It was reported that [...] Read more.

A new series of N,N-bis(alkanol)amine aryl diesters was synthesized and studied as dual P-glycoprotein (P-gp) and carbonic anhydrase XII inhibitors (CA XII). These hybrids should be able to synergistically overcome P-gp mediated multidrug resistance (MDR) in cancer cells. It was reported that the efflux activity of P-gp could be modulated by CA XII, as the pH reduction caused by CA XII inhibition produces a significant decrease in P-gp ATPase activity. The new compounds reported here feature both P-gp and CA XII binding moieties. These hybrids contain a N,N-bis(alkanol)amine diester scaffold found in P-glycoprotein ligands and a coumarin or benzene sulfonamide moiety to target CA XII. Many compounds displayed a dual activity against P-gp and CA XII being active in the Rhd 123 uptake test on K562/DOX cells and in the hCA XII inhibition test. On LoVo/DOX cells, that overexpress both P-gp and CA XII, some coumarin derivatives showed a high MDR reversal effect in Rhd 123 uptake and doxorubicin cytotoxicity enhancement tests. In particular, compounds 7 and 8 showed higher activity than verapamil and were more potent on LoVo/DOX than on K562/DOX cells overexpressing only P-gp. They can be considered as valuable candidates for selective P-gp/CA XII inhibition in MDR cancer cells. Full article

(This article belongs to the Special Issue Multitarget Ligands)

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17 pages, 7634 KiB

Open AccessArticle

Flame-Made Calcium Phosphate Nanoparticles with High Drug Loading for Delivery of Biologics

by Vasiliki Tsikourkitoudi, Jens Karlsson, Padryk Merkl, Edmund Loh, Birgitta Henriques-Normark and Georgios A. Sotiriou

Molecules 2020, 25(7), 1747; https://doi.org/10.3390/molecules25071747 - 10 Apr 2020

Cited by 20 | Viewed by 5147

Abstract

Nanoparticles exhibit potential as drug carriers in biomedicine due to their high surface-to-volume ratio that allows for facile drug loading. Nanosized drug delivery systems have been proposed for the delivery of biologics facilitating their transport across epithelial layers and maintaining their stability against [...] Read more.

Nanoparticles exhibit potential as drug carriers in biomedicine due to their high surface-to-volume ratio that allows for facile drug loading. Nanosized drug delivery systems have been proposed for the delivery of biologics facilitating their transport across epithelial layers and maintaining their stability against proteolytic degradation. Here, we capitalize on a nanomanufacturing process famous for its scalability and reproducibility, flame spray pyrolysis, and produce calcium phosphate (CaP) nanoparticles with tailored properties. The as-prepared nanoparticles are loaded with bovine serum albumin (model protein) and bradykinin (model peptide) by physisorption and the physicochemical parameters influencing their loading capacity are investigated. Furthermore, we implement the developed protocol by formulating CaP nanoparticles loaded with the LL-37 antimicrobial peptide, which is a biological drug currently involved in clinical trials. High loading values along with high reproducibility are achieved. Moreover, it is shown that CaP nanoparticles protect LL-37 from proteolysis in vitro. We also demonstrate that LL-37 retains its antimicrobial activity against Escherichia coli and Streptococcus pneumoniae when loaded on nanoparticles in vitro. Therefore, we highlight the potential of nanocarriers for optimization of the therapeutic profile of existing and emerging biological drugs. Full article

(This article belongs to the Special Issue Nanocarriers for Diagnostics, Imaging, and Drug Delivery: Critical Perspectives on Materials, Technologies, in Vivo Fate)

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18 pages, 2113 KiB

Open AccessArticle

Chemical Constituents with GNMT-Promoter-Enhancing and NRF2-Reduction Activities from Taiwan Agarwood Excoecaria formosana

by Ho-Cheng Wu, Ming-Jen Cheng, Chia-Hung Yen, Yi-Ming Arthur Chen, Yi-Siao Chen, Ih-Sheng Chen and Hsun-Shuo Chang

Molecules 2020, 25(7), 1746; https://doi.org/10.3390/molecules25071746 - 10 Apr 2020

Cited by 15 | Viewed by 3591

Abstract

Hepatocellular carcinoma (HCC) is considered to be a silent killer, and was the fourth leading global cause of cancer deaths in 2018. For now, sorafenib is the only approved drug for advanced HCC treatment. The introduction of additional chemopreventive agents and/or adjuvant therapies [...] Read more.

Hepatocellular carcinoma (HCC) is considered to be a silent killer, and was the fourth leading global cause of cancer deaths in 2018. For now, sorafenib is the only approved drug for advanced HCC treatment. The introduction of additional chemopreventive agents and/or adjuvant therapies may be helpful for the treatment of HCC. After screening 3000 methanolic extracts from the Formosan plant extract bank, Excoecaria formosana showed glycine N-methyltransferase (GNMT)-promoter-enhancing and nuclear factor erythroid 2-related factor 2 (NRF2)-suppressing activities. Further, the investigation of the whole plant of E. formosana led to the isolation of a new steroid, 7α-hydroperoxysitosterol-3-O-β-d-(6-O-palmitoyl)glucopyranoside (1); two new coumarinolignans, excoecoumarin A (2) and excoecoumarin B (3); a new diterpene, excoeterpenol A (4); and 40 known compounds (5–44). Among them, Compounds 38 and 40–44 at a 100 μM concentration showed a 2.97 ± 0.27-, 3.17 ± 1.03-, 2.73 ± 0.23-, 2.63 ± 0.14-, 6.57 ± 0.13-, and 2.62 ± 0.05-fold increase in GNMT promoter activity, respectively. In addition, Compounds 40 and 43 could reduce NRF2 activity, a transcription factor associated with drug resistance, in Huh7 cells with relative activity of 33.1 ± 0.2% and 45.2 ± 2.5%. These results provided the basis for the utilization of Taiwan agarwood for the development of anti-HCC agents. Full article

(This article belongs to the Section Natural Products Chemistry)

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Full article ">Figure 1
Structures of Compounds 1–44. Full article ">Figure 2
Key 1H-1H COSY (━), HMBC (H→C), and ROESY (H↔H) correlations of Compound 1. Full article ">Figure 3
Key 1H-1H COSY (━), HMBC (H→C), and NOESY (H↔H) correlations of Compound 2. Full article ">Figure 4
Key 1H-1H COSY (━), HMBC (H→C), and NOESY (H↔H) correlations of Compound 3. Full article ">Figure 5
KEY 1H-1H COSY (━), HMBC (H→C), and NOESY (H↔H) correlations of Compound 4. Full article ">Figure 6
Glycine N-methyltransferase (GNMT)-promoter-enhancing activity (fold of induction) of compounds from the whole plant of E. formosana. Sample concentration was 100 µM. GNMT activity (fold of induction) = observed activity/solvent control activity; 1,2,3,4,6-penta-O-galloyl-β-d-glucose (PGG) was used as positive control for GNMT activation with 100 µM. Full article ">Figure 7
Nuclear factor erythroid 2-related factor 2 (NRF2) inhibition in Huh7 cells of compounds from the whole plant of E. formosana. Sample concentration was 100 µM. Relative NRF2 activity presented as percentage to solvent control. Retinoic acid is used as positive control for NRF2 inhibition with 1 µM. Full article ">

28 pages, 5732 KiB

Open AccessReview

Azides and Porphyrinoids: Synthetic Approaches and Applications. Part 2—Azides, Phthalocyanines, Subphthalocyanines and Porphyrazines

by Ana R. L. Araújo, Augusto C. Tomé, Carla I. M. Santos, Maria A. F. Faustino, Maria G. P. M. S. Neves, Mário M. Q. Simões, Nuno M. M. Moura, Sultan T. Abu-Orabi and José A. S. Cavaleiro

Molecules 2020, 25(7), 1745; https://doi.org/10.3390/molecules25071745 - 10 Apr 2020

Cited by 8 | Viewed by 4666

Abstract

The reaction between organic azides and alkyne derivatives via the Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC) is an efficient strategy to combine phthalocyanines and analogues with different materials. As examples of such materials, it can be considered the following ones: graphene oxide, carbon nanotubes, silica [...] Read more.

The reaction between organic azides and alkyne derivatives via the Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC) is an efficient strategy to combine phthalocyanines and analogues with different materials. As examples of such materials, it can be considered the following ones: graphene oxide, carbon nanotubes, silica nanoparticles, gold nanoparticles, and quantum dots. This approach is also being relevant to conjugate phthalocyanines with carbohydrates and to obtain new sophisticated molecules; in such way, new systems with significant potential applications become available. This review highlights recent developments on the synthesis of phthalocyanine, subphthalocyanine, and porphyrazine derivatives where CuAAC reactions are the key synthetic step. Full article

(This article belongs to the Special Issue Organic Azides 2019)

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21 pages, 5133 KiB

Open AccessArticle

Nanoparticles Based on Novel Carbohydrate-Functionalized Polymers

by Cláudia D. Raposo, Cristiano A. Conceição and M. Teresa Barros

Molecules 2020, 25(7), 1744; https://doi.org/10.3390/molecules25071744 - 10 Apr 2020

Cited by 8 | Viewed by 3817

Abstract

Polymeric nanoparticles can be used for drug delivery systems in healthcare. For this purpose poly(lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) offer an excellent polymeric matrix. In this work, PLGA and PEG polymers were functionalized with coumarin and carbohydrate moieties such as thymidine, [...] Read more.

Polymeric nanoparticles can be used for drug delivery systems in healthcare. For this purpose poly(lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) offer an excellent polymeric matrix. In this work, PLGA and PEG polymers were functionalized with coumarin and carbohydrate moieties such as thymidine, glucose, galactose, and mannose that have high biological specificities. Using a single oil in water emulsion methodology, functionalized PLGA nanoparticles were prepared having a smooth surface and sizes ranging between 114–289 nm, a low polydispersity index and a zeta potential from −28.2 to −56.0 mV. However, for the corresponding PEG derivatives the polymers obtained were produced in the form of films due to the small size of the hydrophobic core. Full article

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32 pages, 1479 KiB

Open AccessReview

Targeted Radionuclide Therapy of Prostate Cancer—From Basic Research to Clinical Perspectives

by Malwina Czerwińska, Aleksander Bilewicz, Marcin Kruszewski, Aneta Wegierek-Ciuk and Anna Lankoff

Molecules 2020, 25(7), 1743; https://doi.org/10.3390/molecules25071743 - 10 Apr 2020

Cited by 73 | Viewed by 10531

Abstract

Prostate cancer is the most commonly diagnosed malignancy in men and the second leading cause of cancer-related deaths in Western civilization. Although localized prostate cancer can be treated effectively in different ways, almost all patients progress to the incurable metastatic castration-resistant prostate cancer. [...] Read more.

Prostate cancer is the most commonly diagnosed malignancy in men and the second leading cause of cancer-related deaths in Western civilization. Although localized prostate cancer can be treated effectively in different ways, almost all patients progress to the incurable metastatic castration-resistant prostate cancer. Due to the significant mortality and morbidity rate associated with the progression of this disease, there is an urgent need for new and targeted treatments. In this review, we summarize the recent advances in research on identification of prostate tissue-specific antigens for targeted therapy, generation of highly specific and selective molecules targeting these antigens, availability of therapeutic radionuclides for widespread medical applications, and recent achievements in the development of new-generation small-molecule inhibitors and antibody-based strategies for targeted prostate cancer therapy with alpha-, beta-, and Auger electron-emitting radionuclides. Full article

(This article belongs to the Section Medicinal Chemistry)

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15 pages, 1668 KiB

Open AccessFeature PaperArticle

Influence of Instant Controlled Pressure Drop (DIC) on Allergenic Potential of Tree Nuts

by Fatima Vicente, Africa Sanchiz, Rosa Rodríguez-Pérez, Maria Pedrosa, Santiago Quirce, Joseph Haddad, Colette Besombes, Rosario Linacero, Karim Allaf and Carmen Cuadrado

Molecules 2020, 25(7), 1742; https://doi.org/10.3390/molecules25071742 - 10 Apr 2020

Cited by 12 | Viewed by 3503

Abstract

Pistachio and cashew contain allergenic proteins, which causes them to be removed from the diet of allergic people. Previous studies have demonstrated that food processing (thermal and non-thermal) can produce structural and/or conformational changes in proteins by altering their allergenic capacity. In this [...] Read more.

Pistachio and cashew contain allergenic proteins, which causes them to be removed from the diet of allergic people. Previous studies have demonstrated that food processing (thermal and non-thermal) can produce structural and/or conformational changes in proteins by altering their allergenic capacity. In this study, the influence of instant controlled pressure drop (DIC) on pistachio and cashew allergenic capacity has been studied. Western blot was carried out using IgG anti-11S and anti-2S and IgE antibodies from sera of patients sensitized to pistachio and cashew. DIC processing causes changes in the electrophoretic pattern, reducing the number and intensity of protein bands, as the pressure and temperature treatment increment, which results in a remarkable decrease in detection of potentially allergenic proteins. The harshest conditions of DIC (7 bar, 120 s) markedly reduce the immunodetection of allergenic proteins, not only by using IgG (anti 11S and anti 2S) but also when IgE sera from sensitized patients were used for Western blots. Such immunodetection is more affected in pistachio than in cashew nuts, but is not completely removed. Therefore, cashew proteins are possibly more resistant than pistachio proteins. According these findings, instant controlled pressure drop (DIC) can be considered a suitable technique in order to obtain hypoallergenic tree nut flour to be used in the food industry. Full article

(This article belongs to the Special Issue Opportunities and Challenges in High Pressure Processing of Foods)

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9 pages, 916 KiB

Open AccessFeature PaperArticle

Efficacy of Topical Treatment with (−)-Epigallocatechin Gallate, A Green Tea Catechin, in Mice with Cutaneous Leishmaniasis

by Andrea M. Sosa, Agustín Moya Álvarez, Estefanía Bracamonte, Masataka Korenaga, Jorge D. Marco and Paola A. Barroso

Molecules 2020, 25(7), 1741; https://doi.org/10.3390/molecules25071741 - 10 Apr 2020

Cited by 14 | Viewed by 3363

Abstract

The treatment of leishmaniasis includes pentavalent antimony drugs but, because of the side effects, toxicity and cases of treatment failure or resistance, the search of new antileishmanial compounds are necessary. The aims of this study were to evaluate and compare the in vitro [...] Read more.

The treatment of leishmaniasis includes pentavalent antimony drugs but, because of the side effects, toxicity and cases of treatment failure or resistance, the search of new antileishmanial compounds are necessary. The aims of this study were to evaluate and compare the in vitro antileishmanial activity of four green tea catechins, and to assess the efficacy of topical (−)-epigallocatechin gallate in a cutaneous leishmaniasis model. The antileishmanial activity of green tea catechins was evaluated against intracellular amastigotes, and cytotoxicity was performed with human monocytic cell line. BALB/c mice were infected in the ear dermis with Leishmania (Leishmania) amazonensis and treated with topical 15% (−)-epigallocatechin gallate, intraperitoneal Glucantime, and control group. The efficacy of treatments was evaluated by quantifying the parasite burden and by measuring the lesions size. (−)-Epigallocatechin gallate and (−)-epigallocatechin were the most active compounds with IC₅₀ values <59.6 µg/mL and with a selectivity index >1. Topical treatment with (−)-epigallocatechin gallate decreased significantly both lesion size and parasite burden (80.4% inhibition) compared to control group (p < 0.05), and moreover (−)-epigallocatechin gallate showed a similar efficacy to Glucantime (85.1% inhibition), the reference drug for leishmaniasis treatment. Full article

(This article belongs to the Special Issue Drug Discovery for Neglected Diseases)

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Structures of the green tea catechins assayed. Full article ">Figure 2
Evaluation of efficacy of topical treatment with 15% EGCG in BALB/c mice infected with L. (L.) amazonensis. Animals were treated with 15% EGCG during 18 days, once a day, six times a week and Gl was administered by intraperitoneal route, once a day, six times a week (120 mg Sbv/kg/d). Lesions’ sizes of mice treated with topical 15% EGCG decreased significantly at week 10 compared to control group (untreated mice) (p < 0.05). In addition, no difference in lesion size was observed between mice treated with 15% EGCG and Gl, the first-line drug for the treatment of leishmaniasis. Lesions’ sizes in the control group increased as was expected. Full article ">Figure 3
Promastigotes of L. (L.) amazonensis (5 × 103/20 µL) were inoculated in the ear dermis of BALB/c mice. After six weeks postinfection, mice were treated with topical 15% EGCG and Gl. The photomicrographs are showing the efficacy of 15% EGCG and Gl at the end of the experiment (week 10). (A) Lesion with elevated border and central crater of an untreated mouse. (B) Small lesion with thin border of a mouse treated with 15% EGCG. (C) Small papular lesion after treatment with Gl. Full article ">Figure 4
Efficacy of topical treatment with 15% EGCG in BALB/c mice infected with L. (L.) amazonensis. Parasite burden decreased significantly after 18 days of treatment with topical EGCG with respect to control group (p < 0.05). In addition, EGCG showed a similar efficacy to the intraperitoneal Gl treatment. Results represent the mean ± standard deviation of two independent experiments. Full article ">

9 pages, 2868 KiB

Open AccessArticle

Optical Textures and Orientational Structures in Cholesteric Droplets with Conical Boundary Conditions

by Anna P. Gardymova, Mikhail N. Krakhalev and Victor Ya. Zyryanov

Molecules 2020, 25(7), 1740; https://doi.org/10.3390/molecules25071740 - 10 Apr 2020

Cited by 11 | Viewed by 4186

Abstract

Cholesteric droplets dispersed in polymer with conical boundary conditions have been studied. The director configurations are identified by the polarising microscopy technique. The axisymmetric twisted axial-bipolar configuration with the surface circular defect at the droplet’s equator is formed at the relative chirality parameter [...] Read more.

Cholesteric droplets dispersed in polymer with conical boundary conditions have been studied. The director configurations are identified by the polarising microscopy technique. The axisymmetric twisted axial-bipolar configuration with the surface circular defect at the droplet’s equator is formed at the relative chirality parameter

N_{0} \leq 2.9

. The intermediate director configuration with the deformed circular defect is realised at

2.9 < N_{0} < 3.95

, and the layer-like structure with the twisted surface defect loop is observed at

N_{0} \geq 3.95

. The cholesteric layers in the layer-like structure are slightly distorted although the cholesteric helix is untwisted. Full article

(This article belongs to the Special Issue Current Advances in Liquid Crystals)

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15 pages, 1191 KiB

Open AccessArticle

Vine-Canes Valorisation: Ultrasound-Assisted Extraction from Lab to Pilot Scale

by Olena Dorosh, Manuela M. Moreira, Francisca Rodrigues, Andreia F. Peixoto, Cristina Freire, Simone Morais and Cristina Delerue-Matos

Molecules 2020, 25(7), 1739; https://doi.org/10.3390/molecules25071739 - 10 Apr 2020

Cited by 33 | Viewed by 3503

Abstract

Wine production generates large amounts of vine-canes, a devalued by-product that could be used for the recovery of bioactive compounds. In this work, two vine-canes varieties, namely Touriga Nacional (TN) and Tinta Roriz (TR), were submitted to different ultrasound-assisted extraction (UAE) conditions. The [...] Read more.

Wine production generates large amounts of vine-canes, a devalued by-product that could be used for the recovery of bioactive compounds. In this work, two vine-canes varieties, namely Touriga Nacional (TN) and Tinta Roriz (TR), were submitted to different ultrasound-assisted extraction (UAE) conditions. The highest phenolic and flavonoid content was observed for TR extract obtained at lab-scale without an ice bath and pilot-scale after 60 min of extraction (32.6 ± 2.1 and 26.0 ± 1.5 mg gallic acid equivalent/g dry weight (dw) and 9.5 ± 0.6 and 8.3 ± 0.8 mg epicatechin equivalents/g dw, respectively). Further, all extracts demonstrated a high antioxidant activity to scavenge DPPH free radicals with the best value reached by TR at the lab-scale without an ice bath after 30 min and pilot-scale extraction after 60 min (34.2 ± 2.4 and 33.4 ± 2.1 mg trolox equivalents/g dw, respectively). Extracts phenolic composition were also evaluated by HPLC, demonstrating that resveratrol, myricetin and catechin were the main compounds. According to our knowledge, this is the first time that a pilot scale of UAE of phenolic compounds from vine-canes was performed. This paper represents an important step to the use of UAE as an industrial process to recover bioactive compounds. Full article

(This article belongs to the Special Issue Waste and By-Products from Agricultural Production for Innovative Health Applications)

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15 pages, 728 KiB

Open AccessReview

New Frontiers for the Use of IP6 and Inositol Combination in Treating Diabetes Mellitus: A Review

by Felix O. Omoruyi, Dewayne Stennett, Shadae Foster and Lowell Dilworth

Molecules 2020, 25(7), 1720; https://doi.org/10.3390/molecules25071720 - 10 Apr 2020

Cited by 33 | Viewed by 10395

Abstract

Inositol, or myo-inositol, and associated analog molecules, including myo-inositol hexakisphosphate, are known to possess beneficial biomedical properties and are now being widely studied. The impact of these compounds in improving diabetic indices is significant, especially in light of the high cost of treating [...] Read more.

Inositol, or myo-inositol, and associated analog molecules, including myo-inositol hexakisphosphate, are known to possess beneficial biomedical properties and are now being widely studied. The impact of these compounds in improving diabetic indices is significant, especially in light of the high cost of treating diabetes mellitus and associated disorders globally. It is theorized that, within ten years, the global population of people with the disease will reach 578 million individuals, with the cost of care projected to be approximately 2.5 trillion dollars. Natural alternatives to pharmaceuticals are being sought, and this has led to studies involving inositol, and myo-inositol-hexakisphosphate, also referred to as IP6. It has been reported that IP6 can improve diabetic indices and regulate the activities of some metabolic enzymes involved in lipid and carbohydrate metabolism. Current research activities have been focusing on the mechanisms of action of inositol and IP6 in the amelioration of the indices of diabetes mellitus. We demonstrated that an IP6 and inositol combination supplement may regulate insulin secretion, modulate serum leptin concentrations, food intake, and associated weight gain, which may be beneficial in both prediabetic and diabetic states. The supplement attenuates vascular damage by reducing red cell distribution width. Serum HDL is increased while serum triglycerides tend to decrease with consumption of the combination supplement, perhaps due to the modulation of lipogenesis involving reduced serum lipase activity. We also noted increased fecal lipid output following combination supplement consumption. Importantly, liver function was found to be preserved. Concurrently, serum reactive oxygen species production was reduced, indicating that inositol and IP6 supplement consumption may reduce free radical damage to tissues and organs as well as serum lipids and blood glucose by preserving liver function. This review provides an overview of the findings associated with inositol and IP6 supplementation in the effective treatment of diabetes with a view to proposing the potential mechanisms of action. Full article

(This article belongs to the Special Issue Bioactivity of Inositol Phosphates)

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18 pages, 3028 KiB

Open AccessArticle

Design, Synthesis of Novel Tetrandrine-14-l-Amino Acid and Tetrandrine-14-l-Amino Acid-Urea Derivatives as Potential Anti-Cancer Agents

by Sheng-Cao Hu, Jin Yang, Chao Chen, Jun-Rong Song and Wei-Dong Pan

Molecules 2020, 25(7), 1738; https://doi.org/10.3390/molecules25071738 - 9 Apr 2020

Cited by 7 | Viewed by 3434

Abstract

Tetrandrine, a dibenzyltetrahydroisoquinoline alkaloid isolated from the root of the traditional Chinese medicinal plant Stephania tetrandra S. Moore, a member of the Menispermaceae, showed anti-cancer activity by inhibiting cell proliferation, preventing cell cycle progress and induction of cell death and autophagy. In this [...] Read more.

Tetrandrine, a dibenzyltetrahydroisoquinoline alkaloid isolated from the root of the traditional Chinese medicinal plant Stephania tetrandra S. Moore, a member of the Menispermaceae, showed anti-cancer activity by inhibiting cell proliferation, preventing cell cycle progress and induction of cell death and autophagy. In this study, twelve tetrandrine-l-amino acid derivatives and twelve tetrandrine-14-l-amino acid-urea derivatives were designed and synthesized, using C14-aminotetrandrine as raw material. Then the preliminary in vitro anti-cancer activities of these derivatives against human breast cancer cell line MDA-MB-231, human leukemia cell lines HEL and K562 were evaluated. The in vitro cytotoxicity results showed that these derivatives exhibited potent inhibitory effects on cancer cell growth, and the primary structure-activity relationships were evaluated. Notably, compound 3f exhibited satisfactory anticancer activity against all three cancer cell lines, especially the HEL cell line, with the IC₅₀ value of 0.23 µM. Further research showed that 3f could induce G1/S cycle arrest and apoptosis in a dose- and time- dependent manner on the leukemia cell line HEL. The results suggested that 3f may be used as a potential anti-cancer agent for human leukemia. Full article

(This article belongs to the Special Issue Design, Synthesis and Applications of New Anti-Cancer Agents)

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The structure of tetrandrine. Full article ">Figure 2
The structures of floxuridine prodrug (a) and brivanib (b). Full article ">Figure 3
The inhibitory activity on proliferation of human leukemia HEL cell of 3f. (A) Cellular morphological alteration of HEL cell at different concentrations of 3f after 24 h of drug treatment. (B) The inhibition of 3f on HEL cell growth after 72 h. Full article ">Figure 4
Apoptosis induced by compound 3f in HEL cell line. (A) Compound 3f had effect in retardation of cell cycle progression in HEL cell line. The cell cycle progression was retarded in the G1/S phase. HEL cell line was treated with compound 3f for 24 h. (B) Compound 3f induced apoptosis in HEL cell line. The HEL cell line was treated with compound 3f for 24 h and analyzed by flow cytometry, using Annexin V/PI staining. Full article ">Scheme 1
The synthetic routes of tetrandrine derivatives. Reagents and Conditions: (a) mixed acid (20 eq, HNO3: acetic anhydride = 7:10 v/v), DCM, 0 °C to r.t., 4 h (93%); (b) Pd/C (5%), hydrazine hydrate (80 eq), MeOH, 65 °C, 3.5 h (84%); (c) Boc-l-amino acid (1.1 eq), EDCI (1.1 eq), HOBT (0.4 eq), DCM, r.t., 1.5–3 h (78-88%); (d) TFA (1.0 eq), DCM, 0 °C to r.t., 4 h (97%); (e) isocyanate (1.1 eq), triethylamine (0.2 eq), DCM, r.t., 0.5–1.5 h (90–95%). Full article ">

16 pages, 2628 KiB

Open AccessArticle

Suppressive Effect of Arctium Lappa L. Leaves on Retinal Damage Against A2E-Induced ARPE-19 Cells and Mice

by Dong Hee Kim, Yae Rim Choi, Jaewon Shim, Yun-Sang Choi, Yun Tai Kim, Mina Kyungmin Kim and Min Jung Kim

Molecules 2020, 25(7), 1737; https://doi.org/10.3390/molecules25071737 - 9 Apr 2020

Cited by 16 | Viewed by 4046

Abstract

Age-related macular degeneration (AMD) is a major cause of irreversible loss of vision with 80–90% of patients demonstrating dry type AMD. Dry AMD could possibly be prevented by polyphenol-rich medicinal foods by the inhibition of N-retinylidene-N-retinylethanolamine (A2E)-induced oxidative stress and cell damage. Arctium [...] Read more.

Age-related macular degeneration (AMD) is a major cause of irreversible loss of vision with 80–90% of patients demonstrating dry type AMD. Dry AMD could possibly be prevented by polyphenol-rich medicinal foods by the inhibition of N-retinylidene-N-retinylethanolamine (A2E)-induced oxidative stress and cell damage. Arctium lappa L. (AL) leaves are medicinal and have antioxidant activity. The purpose of this study was to elucidate the protective effects of the extract of AL leaves (ALE) on dry AMD models, including in vitro A2E-induced damage in ARPE-19 cells, a human retinal pigment epithelial cell line, and in vivo light-induced retinal damage in BALB/c mice. According to the total phenolic contents (TPCs), total flavonoid contents (TFCs) and antioxidant activities, ALE was rich in polyphenols and had antioxidant efficacies on 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), and 2′,7′-dichlorofluorescin diacetate (DCFDA) assays. The effects of ALE on A2E accumulation and A2E-induced cell death were also monitored. Despite continued exposure to A2E (10 μM), ALE attenuated A2E accumulation in APRE-19 cells with levels similar to lutein. A2E-induced cell death at high concentration (25 μM) was also suppressed by ALE by inhibiting the apoptotic signaling pathway. Furthermore, ALE could protect the outer nuclear layer (ONL) in the retina from light-induced AMD in BALB/c mice. In conclusion, ALE could be considered a potentially valuable medicinal food for dry AMD. Full article

(This article belongs to the Section Natural Products Chemistry)

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Figure 1
Extraction of AL and total polyphenol contents in extract of AL leaves (ALE). (A) Ethanolic extracts and extraction yield of ALE. (B) TPCs in ALE in a dose range from 5 to 100 μg/mL. (C) TFCs in ALE in a dose range from 10 to 100 μg/mL. The values represent the mean ± SD (n ≥ 3). ***p < 0.001 vs blank group, one-way ANOVA with Tukey’s post hoc test. TPC, total phenolic content; TFC, total flavonoid content; GAE, gallic acid equivalent; QE, quercetin. Full article ">Figure 2
Antioxidant activity of ALE. 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay (A), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assay (B), and ferric reducing antioxidant power (FRAP) assay (C) were used to monitor the antioxidant activities of ALE at different doses. (D) ARPE-19 cells, a human retinal pigment epithelial cell line, were treated with ALE prior to N-retinylidene-N-retinylethanolamine (A2E) and intracellular reactive oxygen species (ROS) generation was monitored with the use of 5-(and-6)-chloromethyl-2′,7′-dichlorodihydrofluorescein diacetate, acetyl ester (CM-H2DCFDA). The values represent the mean ± SD (n ≥ 3). *p < 0.05, ***p < 0.001 vs blank group, one-way ANOVA with Tukey’s post hoc test. Full article ">Figure 3
Characteristics of synthesized A2E. (A) Chemical structure of A2E. (B) Chromatogram of HPLC-purified A2E by HPLC. (C) UV spectra and structure of synthesized A2E. (D,E) Optimization of A2E concentration. ARPE-19 cells were treated with A2E at 10 μM (D) or 25 μM (E) for 24 h, and cell viability was measured by cell counting kit (CCK)-8 kit at different time points. The values represent the mean ± SD (n ≥ 3). **p < 0.01, ***p < 0.001 vs 0 h group, one-way ANOVA with Tukey’s post hoc test. Full article ">Figure 4
Protective effects of ALE on A2E accumulation and A2E-induced cell death in ARPE-19 cells. (A) Cell viability of ARPE-19 cells treated only with lutein or ALE. ARPE-19 cells were incubated with lutein or ALE (5, 10, 30 μg/mL) for 24 h and the cell viability was measured using the CCK-8 kit. (B) Inhibition of intracellular A2E accumulation by ALE pretreatment. ARPE-19 cells were treated with ALE (5, 10, and 30 μg/mL) on days 2, 5, and 8, and with A2E (10 μM) on days 3, 6, and 9. On the last day (day 10), A2E in ARPE-19 cells was extracted, analyzed by HPLC, quantified using an external A2E standard curve, and normalized to protein level. The values represent the mean ± SD (n ≥ 3). * p < 0.05, ** p < 0.01, *** p < 0.001 vs A2E group, one-way ANOVA with Tukey’s post hoc test. (C) Inhibition of A2E-induced cell death by ALE pretreatment. ARPE-19 cells were incubated with lutein or ALE (5, 10, and 30 μg/mL) for 24 h, prior to A2E treatment (25 μM) for 24 h. Then, cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The values represent the mean ± SD (n ≥ 3). ### p < 0.001 vs C (control) group; *** p < 0.001 vs A2E group, one-way ANOVA with Tukey’s post hoc test. (D) Protein expression of apoptosis-associated factors in A2E-laden APRE-19 cells. Full article ">Figure 5
Inhibitory effect of ALE on light-induced retinal damage. (A) Representative hematoxylin and eosin (H&E) stained images in light-induced age-related macular degeneration (AMD) model. BALB/c mice (n = 6) were treated with vehicle, lutein (50 mg/kg), or ALE (50, 100, and 200 mg/kg) for 4 weeks and exposed to white light at 10,000 lux in light cages for 6 h. After exposure, mice were given inhaled anesthesia with isoflurane immediately and were euthanized to remove the eyes. (B) Stained region in ONL layer was calculated using metamorph and expressed in ONL nuclei area (%). The values represent the mean ± SD (n = 3). ###: p < 0.001 vs control group; *** p < 0.001 vs light exposure group, one-way ANOVA with Tukey’s post hoc test. OS, outer segments; IS, inner segments; ONL, outer nuclear layer; INL, inner nuclear layer; GCL, ganglion cell layer. Full article ">Figure 6
Scheme of treatment schedule. (A) Schedule for the inhibitory effect of ALE on A2E accumulation in ARPE-19 cells. (B) Schedule for rodent study. Full article ">

10 pages, 1673 KiB

Open AccessArticle

Estimation of Chemical Composition of Pork Trimmings by Use of Density Measurement—Hydrostatic Method

by Lech Adamczak, Marta Chmiel, Tomasz Florowski and Dorota Pietrzak

Molecules 2020, 25(7), 1736; https://doi.org/10.3390/molecules25071736 - 9 Apr 2020

Cited by 3 | Viewed by 2711

Abstract

This study aims to determine the possibility of using density measurements by using the hydrostatic method for the estimation of the chemical composition of pork. The research material included 75 pork samples obtained during industrial butchering and cutting. The density measurements were performed [...] Read more.

This study aims to determine the possibility of using density measurements by using the hydrostatic method for the estimation of the chemical composition of pork. The research material included 75 pork samples obtained during industrial butchering and cutting. The density measurements were performed using the hydrostatic method based on Archimedes’ principle. The meat samples were minced, and the content of the basic chemical components in them was determined. The usefulness of density measurement using the hydrostatic method in chemical composition estimation was determined by analyzing the correlation for the entire population, and after grouping the samples with a low (<15%), medium (15–25%), and high (>25%) fat content. High (in absolute value) coefficients of correlation between the meat density and the content of water (0.96), protein (0.94), and fat (−0.96) were found based on the results obtained. In order to achieve higher accuracy of the estimation, the applied regression equations should be adjusted to the presumed fat content in the meat. The standard error of prediction (SEP) values ranged from 0.67% to 2.82%, which indicates that the calculated estimation accuracy may be sufficient for proper planning of the production. Higher SEP values were found in fat content estimation and the lowest ones were found in protein content estimation. Full article

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9 pages, 1183 KiB

Open AccessFeature PaperArticle

Analysis of Total Thiols in the Urine of a Cystathionine β-Synthase-Deficient Mouse Model of Homocystinuria Using Hydrophilic Interaction Chromatography

by Chun-Fang Chang, Kenji Hamase and Makoto Tsunoda

Molecules 2020, 25(7), 1735; https://doi.org/10.3390/molecules25071735 - 9 Apr 2020

Cited by 3 | Viewed by 2949

Abstract

Homocysteine and related thiols (cysteine, cysteinylglycine, and glutathione) in the urine of a cystathionine β-synthase (CBS)-deficient mouse model were quantified using hydrophilic interaction chromatography with fluorescence detection. Urine samples were incubated with tris(2-carboxyethyl) phosphine to reduce disulfide bonds into thiols. After deproteinization, thiols [...] Read more.

Homocysteine and related thiols (cysteine, cysteinylglycine, and glutathione) in the urine of a cystathionine β-synthase (CBS)-deficient mouse model were quantified using hydrophilic interaction chromatography with fluorescence detection. Urine samples were incubated with tris(2-carboxyethyl) phosphine to reduce disulfide bonds into thiols. After deproteinization, thiols were fluorescently derivatized with ammonium 7-fluoro-2,1,3-benzoxadiazole-4-sulfonate (SBD-F). Homocysteine, cysteine, cysteinylglycine, and glutathione in mouse urine were analyzed using an amide-type column with a mobile phase of acetonitrile/120 mM ammonium formate buffer (pH 3.0) (81:19). The developed method was well-validated. Thiol concentrations in the urine of CBS-wild type (-WT), -heterozygous (-Hetero), and -knockout (-KO) mice were quantified using the developed method. As expected, total homocysteine concentration in CBS-KO mice was significantly higher than that in CBS-WT and CBS-Hetero mice. The developed method shows promise for diagnoses in preclinical and clinical studies. Full article

(This article belongs to the Special Issue Biological Sample Analysis by Liquid Chromatography II)

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Figure 1
Metabolism pathway of homocysteine-related thiols and structures of target thiol compounds. Hcy, homocysteine; Cys, cysteine; GSH, glutathione, CysGly, cysteinylglycine, CBS, cystathionine β-synthase. Full article ">Figure 2
Chromatograms of ammonium 7-fluoro-2,1,3-benzoxadiazole-4-sulfonate (SBD)-thiol standard solution under different buffer pH. Mobile phase: acetonitrile/40 mM ammonium formate (80:20). Peaks—1, SBD-homocysteine (-Hcy); 2, SBD- cystathionine (-Cys); 3, SBD-Cysteinylglycine (-CysGly); and 4, SBD-Glutathione (-GSH). Full article ">Figure 3
Chromatograms of mouse urine samples with different buffer concentration. Mobile phase—acetonitrile/ammonium formate (pH 3.0) (80:20). Peaks—1, SBD-Hcy; 2, SBD-Cys; 3, SBD-CysGly; UK, unknown peak. Full article ">Figure 4
Chromatograms of (a) 1 µM SBD-thiols standard solution and (b) mouse urine samples under optimized conditions. Mobile phase—acetonitrile/120 mM ammonium formate (pH 3.0) (81:19). Peaks—1, SBD-Hcy; 2, SBD-Cys; 3, SBD-CysGly; 4, SBD-GSH. Full article ">Figure 5
Chromatograms of (a) CBS-wild type (CBS-WT), (b) CBS-heterozygous (CBS-Hetero), and (c) CBS-knockout (CBS-KO) mouse urine samples. Mobile phase—acetonitrile/120 mM ammonium formate (pH 3.0) (81:19). Peaks—1, SBD-Hcy; 2, SBD-Cys; 3, SBD-CysGly; 4, SBD-GSH. Full article ">Figure 6
Concentration of thiols in CBS-WT, -Hetero, and -KO mouse urine samples. Numbers of samples—WT, n = 4; Hetero, n = 9; KO, n = 7. Error bars—standard deviation. Full article ">

13 pages, 1726 KiB

Open AccessReview

Carbohydrates—Key Players in Tobacco Aroma Formation and Quality Determination

by Marija Banožić, Stela Jokić, Đurđica Ačkar, Marijana Blažić and Drago Šubarić

Molecules 2020, 25(7), 1734; https://doi.org/10.3390/molecules25071734 - 9 Apr 2020

Cited by 73 | Viewed by 7118

Abstract

Carbohydrates are important compounds in natural products where they primarily serve as a source of energy, but they have important secondary roles as precursors of aroma or bioactive compounds. They are present in fresh and dried (cured) tobacco leaves as well. The sugar [...] Read more.

Carbohydrates are important compounds in natural products where they primarily serve as a source of energy, but they have important secondary roles as precursors of aroma or bioactive compounds. They are present in fresh and dried (cured) tobacco leaves as well. The sugar content of tobacco depends on the tobacco variety, harvesting, and primarily on the curing conditions (temperature, time and moisture). If the process of curing employs high temperatures (flue-curing and sun-curing), final sugar content is high. In contrast, when air curing has a lower temperature, at the end of the process, sugar level is low. Beside simple sugars, other carbohydrates reported in tobacco are oligosaccharides, cellulose, starch, and pectin. Degradation of polysaccharides results in a higher yield of simple sugars, but at the same time reduces sugars oxidization and transfer into carbon dioxide and water. Loss of sugar producers will compensate with added sugars, to cover undesirable aroma properties and achieve a better, pleasant taste during smoking. However, tobacco carbohydrates can be precursors for many harmful compounds, including formaldehyde and 5-hydroxymethylfurfural. Keeping in mind that added sugars in tobacco production are unavoidable, it is important to understand all changes in carbohydrates from harvesting to consuming in order to achieve better product properties and avoid the formation of harmful compounds. This review summarizes current knowledge about tobacco carbohydrates, including changes during processing with special focus on carbohydrates as precursors of harmful compounds during smoking. Full article

(This article belongs to the Section Natural Products Chemistry)

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12 pages, 2160 KiB

Open AccessCommunication

Towards Building Blocks for Supramolecular Architectures Based on Azacryptates

by Ana Miljkovic, Sonia La Cognata, Greta Bergamaschi, Mauro Freccero, Antonio Poggi and Valeria Amendola

Molecules 2020, 25(7), 1733; https://doi.org/10.3390/molecules25071733 - 9 Apr 2020

Cited by 6 | Viewed by 2953

Abstract

In this work, we report the synthesis of a new bis(tris(2-aminoethyl)amine) azacryptand L with triphenyl spacers. The binding properties of its dicopper complex for aromatic dicarboxylate anions (as TBA salts) were investigated, with the aim to obtain potential building blocks for supramolecular structures [...] Read more.

In this work, we report the synthesis of a new bis(tris(2-aminoethyl)amine) azacryptand L with triphenyl spacers. The binding properties of its dicopper complex for aromatic dicarboxylate anions (as TBA salts) were investigated, with the aim to obtain potential building blocks for supramolecular structures like rotaxanes and pseudo-rotaxanes. As expected, UV-Vis and emission studies of [Cu₂L]⁴⁺ in water/acetonitrile mixture (pH = 7) showed a high affinity for biphenyl-4,4′-dicarboxylate (dfc²⁻), with a binding constant of 5.46 log units, due to the best match of the anion bite with the Cu(II)-Cu(II) distance in the cage’s cavity. Compared to other similar bistren cages, the difference of the affinity of [Cu₂L]⁴⁺ for the tested anions was not so pronounced: conformational changes of L seem to promote a good interaction with both long (e.g., dfc²⁻) and short anions (e.g., terephthalate). The good affinity of [Cu₂L]⁴⁺ for these dicarboxylates, together with hydrophobic interactions within the cage’s cavity, may promote the self-assembly of a stable 1:1 complex in water mixture. These results represent a good starting point for the application of these molecular systems as building units for the design of new supramolecular architectures based on non-covalent interactions, which could be of interest in all fields related to supramolecular devices. Full article

(This article belongs to the Special Issue Molecular Recognition and Self-Assembly in Chemistry and Medicine)

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Figure 1
Structures of the azacryptand L, the fluorescent indicator (6-TAMRA) and the carboxylates investigated in this work. Full article ">Figure 2
UV-Vis spectra taken upon titration of [Cu2L](CF3SO3)4 (50 μM) with dfc2− (as the TBA salt) in H2O:CH3CN 1:4 at pH 7 (0.02M HEPES buffer; path length = 10 cm). The inset shows the titration profiles at 650 and 800 nm, with the superimposed distribution diagrams of the dicopper complex (C) containing species: purple line, [Cu2L(dfc)]2+; black line, [Cu2L]4+; LogK11 = 5.46(2). Full article ">Figure 3
Normalized emission spectra taken upon titration of 6-TAMRA, I (0.25 μM, λexc = 548 nm) with [Cu2L](CF3SO3)4 (C) in H2O:CH3CN 1:4 at pH 7 (0.02 M HEPES buffer). The inset shows the titration profile as the normalized intensity at 570 nm vs. eqv. of the added complex, with the superimposed distribution diagram of the indicator containing species (I, 6-TAMRA; C, [Cu2L]4+; IC and IC2, 1:1 and 1:2 I:C adducts, respectively). Full article ">Figure 4
Normalized emission spectra taken upon titration of the chemosensing ensemble solution (0.25 μM I; 50 μM C, λexc = 548 nm) with dfc2− (as the TBA salt) in H2O:CH3CN 1:4 at pH 7 (0.02 M HEPES buffer). The inset shows the titration profile, as % I/Imax (Imax= emission intensity of I in the absence of C) vs. eqv. of the dicarboxylate anion, with the superimposed distribution diagram of the indicator containing species (I = 6-TAMRA; C = [Cu2L]4+; IC and IC2 = 1:1 and 1:2 I:C adducts, respectively). Full article ">Figure 5
Competition assays with dicarboxylates (as the TBA salts, see the inset symbols) using chemosensing ensemble solutions of C (50 μM) and I (0.25 μM) in 1:4 H2O:CH3CN at pH 7 (0.02 M HEPES buffer); the families of profiles show the trend of I/Imax vs. equivalents of the added anion (a) and I/Imax vs. anion concentration (b). Full article ">Figure 6
Lateral (a) and front (b) views of the calculated structure of the complex [Cu2L(dfc)]2+. Full article ">Figure 7
Top: zoom scans of the peaks at 711 m/z and 743 m/z, obtained from the experimental mass spectrum of an equimolar solution of [Cu2L]4+ and either dfc2− (a) or sdbz2− (b) in CH3CN:H2O 4:1. Bottom: simulated peaks, calculated for the double charged adduct [Cu2C86H86N8O4]2+ (a) and [Cu2C86H86N8O6S]2+ (b). Full article ">

15 pages, 1692 KiB

Open AccessArticle

Synthesis and Evaluation of Artificial Nucleic Acid Bearing an Oxanorbornane Scaffold

by Hibiki Komine, Shohei Mori, Kunihiko Morihiro, Kenta Ishida, Takumi Okuda, Yuuya Kasahara, Hiroshi Aoyama, Takao Yamaguchi and Satoshi Obika

Molecules 2020, 25(7), 1732; https://doi.org/10.3390/molecules25071732 - 9 Apr 2020

Cited by 5 | Viewed by 3649

Abstract

Natural oligonucleotides have many rotatable single bonds, and thus their structures are inherently flexible. Structural flexibility leads to an entropic loss when unwound oligonucleotides form a duplex with single-stranded DNA or RNA. An effective approach to reduce such entropic loss in the duplex-formation [...] Read more.

Natural oligonucleotides have many rotatable single bonds, and thus their structures are inherently flexible. Structural flexibility leads to an entropic loss when unwound oligonucleotides form a duplex with single-stranded DNA or RNA. An effective approach to reduce such entropic loss in the duplex-formation is the conformational restriction of the flexible phosphodiester linkage and/or sugar moiety. We here report the synthesis and biophysical properties of a novel artificial nucleic acid bearing an oxanorbornane scaffold (OxNorNA), where the adamant oxanorbornane was expected to rigidify the structures of both the linkage and sugar parts of nucleic acid. OxNorNA phosphoramidite with a uracil (U) nucleobase was successfully synthesized over 15 steps from a known sugar-derived cyclopentene. Thereafter, the given phosphoramidite was incorporated into the designed oligonucleotides. Thermal denaturation experiments revealed that oligonucleotides modified with the conformationally restricted OxNorNA-U properly form a duplex with the complementally DNA or RNA strands, although the T_m values of OxNorNA-U-modified oligonucleotides were lower than those of the corresponding natural oligonucleotides. As we had designed, entropic loss during the duplex-formation was reduced by the OxNorNA modification. Moreover, the OxNorNA-U-modified oligonucleotide was confirmed to have extremely high stability against 3′-exonuclease activity, and its stability was even higher than those of the phosphorothioate-modified counterparts (Sp and Rp). With the overall biophysical properties of OxNorNA-U, we expect that OxNorNA could be used for specialized applications, such as conformational fixation and/or bio-stability enhancement of therapeutic oligonucleotides (e.g., aptamers). Full article

(This article belongs to the Special Issue Recent Development of Nucleic Acid Analogs)

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Graphical abstract
Full article ">Figure 1
Conformational restrictions of natural oligonucleotides. Full article ">Figure 2
Structures of artificial nucleic acid bearing an oxanorbornane scaffold (OxNorNA), isoDNA, and TNA. Full article ">Figure 3
ORTEP drawing of the X-ray crystal structure of 12 (thermal ellipsoids at the 50% probability level). Full article ">Figure 4
Circular dichroism (CD) spectra of OxNorNA-modified oligonucleotides (ON1 and ON2) and their natural counterparts (ON4 and ON5) in the presence or absence of a complementary strand (ssDNA or ssRNA). (a) ON1 and ON4 in the presence or absence of ssDNA; (b) ON1 and ON4 in the presence or absence of ssRNA; (c) ON2 and ON5 in the presence or absence of ssDNA; (d) ON2 and ON5 in the presence or absence of ssRNA. Conditions: 10 mM sodium phosphate buffer (pH 7.2) containing 100 mM NaCl and 4 μM of each oligonucleotide at 10 °C. The sequences of the target ssDNA and ssRNA are 5′-d(AGCAAAAAACGC)-3′ and 5′-r(AGCAAAAAACGC)-3′, respectively. Full article ">Figure 5
Enzymatic stability of the OxNorNA-modified oligonucleotide. Conditions: 0.133 ug/mL snake venom phosphodiesterase (svPDE), 10 mM MgCl2, 50 mM Tris-HCl (pH 8.0), and 2 μM each oligonucleotide at 37 °C. The sequence of the oligonucleotides used was 5′-d(TTT TTT TTT X)-3′. X = OxNorNA-U (red diamond, ON3), X = 5′-(S)-phosphorothioate (PS)-modified thymidine (orange square, ON6), X = 5′-(R)-PS-modified thymidine (gray triangle, ON7), and X = locked nucleic acid (LNA)-T (blue cross, ON 8). Full article ">Scheme 1
Synthesis of OxNorNA-uracil (U) phosphoramidite 14. Reagents and conditions: (i) NaH, BnBr, DMF, 0 °C, 92%; (ii) thexylborane, THF, 0 °C to rt; (iii) NaBO3·H2O, H2O, 0 °C to rt, 90% over 2 steps; (iv) tert-butyldimethylchlorosilane (TBSCl), imidazole, DMF, rt, 74%; (v) HCOONH4, Pd/C, EtOH, reflux, 91%; (vi) triethylchlorosilane (TESCl), 2,6-lutidine, CH2Cl2, –78 °C, 86%; (vii) trifluoromethanesulfonic anhydride (Tf2O), pyridine, CH2Cl2, 0 °C; (viii) NaN3, DMF, rt, 71% over 2 steps; (ix) HCOONH4, Pd/C, THF, rt, 98%; (x) 3-methoxyacryloyl isocyanate, THF, –40 °C to rt; (xi) NH4OH, EtOH, 120 °C (sealed tube), 48% over 2 steps; (xii) methanesulfonyl chloride (MsCl), Et3N, CH2Cl2, 0 °C, 77%; (xiii) CeCl3·7H2O, oxalic acid, MeCN, rt, 66%; (xiv) aq. NaOH, 1,4-dioxane, rt, 72%; (xv) 4,4′-dimethoxytrityl trifluoromethanesulfonate (DMTrOTf), CH2Cl2, pyridine, 2,6-lutidine, 0 °C to rt, 93%; (xvi) 2-cyanoethyl N,N-diisopropylchlorophosphoramidite, N,N-diisopropylethylamine (DIPEA), 1-methylimidazole, MeCN, 0 °C to rt, 56%. Full article ">

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