Antibiotics

Research

Jump to: Review

18 pages, 3963 KiB

Open AccessArticle

Vismia guianensis Improves Survival of Tenebrio molitor and Mice During Lethal Infection with Candida albicans

by Arthur André Castro Costa, Elizangela Pestana Motta, Aluísio Silva Oliveira, Pamela Gomes Santos, Josivan Regis Farias, Danielle Cristine Gomes Franco, Mayara Cristina Pinto Silva, Nicolle Teixeira Barbosa, Simone Batista Muniz, Luís Douglas Miranda. Silva, Lucilene Amorim Silva, Claudia Quintino Rocha, Flavia Raquel Fernandes Nascimento and Rosane Nassar Meireles Guerra

Antibiotics 2025, 14(1), 72; https://doi.org/10.3390/antibiotics14010072 (registering DOI) - 11 Jan 2025

Viewed by 249

Abstract

Background/Objectives: Vismia guianensis is a vegetal species popularly used to treat fungal infections. This study evaluated the anti-Candida effect of V. guianensis extract after C. albicans lethal infection in Tenebrio molitor larvae and mice. Methods and Results: The chemical profile [...] Read more.

Background/Objectives: Vismia guianensis is a vegetal species popularly used to treat fungal infections. This study evaluated the anti-Candida effect of V. guianensis extract after C. albicans lethal infection in Tenebrio molitor larvae and mice. Methods and Results: The chemical profile analysis of a hydroethanolic extract of the leaves of V. guianensis (EHVG) identified 14 compounds. Two sets of experiments used T. molitor larvae. To evaluate toxicity, the uninfected larvae were treated with EHVG or anthraquinone. We considered the following groups: the controls received PBS; ANFO B received amphotericin B (600 mg/mL); EHVG received the extract; and ANTQ received anthraquinone. The extract and anthraquinone resulted in low-level toxicity in the T. molitor larvae. Another set of experiments evaluated the EHVG effect during lethal infection with Candida albicans. The T. molitor larvae were treated intracelomically (ic/10 μL). Treatment with EHVG efficiently improved the survival of the larvae after lethal infection (60%), probably due to the reduction in CFUs. In the mice, the antifungal effect of EHVG was determined in three groups of immunosuppressed Swiss mice (cyclophosphamide, 50 mg/kg/ip) infected with C. albicans (1 × 10⁷ CFU/ip). The control animals were infected and untreated; the ANFO B animals were infected and treated with amphotericin B (600 µg/kg/ip); and the EHVG animals were infected and treated with the extract (5 mg/kg/orally). A SHAM group (uninfected and untreated) was also included. Survival was assessed for 5 days. The extract increased the mice’s survival (60%) and life expectancy, reducing the CFU counts in the peritoneum and blood. EHVG also increased the number of blood neutrophils and peritoneal macrophages. These systemic activities are likely associated with the presence of flavonoids in the extract. Conclusions: The beneficial effects of EHVG in lethal sepsis are related to an antifungal effect, with the number of CFUs decreasing in the larvae and the mice. In addition, EHVG showed immunological activity in the mice, considering immune cell distribution and cytokine production. Full article

(This article belongs to the Special Issue Antimicrobial and Anti-Infective Activity of Natural Products, 2nd Edition)

► Show Figures

Figure 1

19 pages, 4130 KiB

Open AccessArticle

Identification and Bioactivity Analysis of a Novel Bacillus Species, B. maqinnsis sp. nov. Bos-x6-28, Isolated from Feces of the Yak (Bos grunniens)

by Qiang Ma, Xin Xiang, Yan Ma, Guangzhi Li, Xingyu Liu, Boai Jia, Wenlin Yang, Hengxia Yin and Benyin Zhang

Antibiotics 2024, 13(12), 1238; https://doi.org/10.3390/antibiotics13121238 - 23 Dec 2024

Viewed by 495

Abstract

Background: The identification of novel bacterial species from the intestines of yaks residing on the Qinghai–Tibet Plateau is pivotal in advancing our understanding of host–microbiome interactions and represents a promising avenue for microbial drug discovery. Methods: In this study, we conducted a polyphasic [...] Read more.

Background: The identification of novel bacterial species from the intestines of yaks residing on the Qinghai–Tibet Plateau is pivotal in advancing our understanding of host–microbiome interactions and represents a promising avenue for microbial drug discovery. Methods: In this study, we conducted a polyphasic taxonomic analysis and bioactive assays on a Bacillus strain, designated Bos-x6-28, isolated from yak feces. Results: The findings revealed that strain Bos-x6-28 shares a high 16S rRNA gene sequence similarity (98.91%) with B. xiamenensis HYC-10^T and B. zhangzhouensis DW5-4^T, suggesting close phylogenetic affinity. Physiological and biochemical characterizations demonstrated that Bos-x6-28 could utilize nine carbon sources, including D-galactose, inositol, and fructose, alongside nine nitrogen sources, such as threonine, alanine, and proline. Analysis of biochemical markers indicated that Bos-x6-28’s cell wall hydrolysates contained mannose, glucose, and meso-2,6-diaminopimelic acid, while menaquinone-7 (MK-7), phosphatidylethanolamine (PE), phosphatidylcholine (PC), and phosphatidylglycerol (DPG) were found in the cell membrane. The primary cellular fatty acids included C16:0 (28.00%), cyclo-C17:0 (19.97%), C14:0 (8.75%), cyclo-C19:0 (8.52%), iso-C15:0 (5.49%), anteiso-C15:0 (4.61%), and C12:0 (3.15%). Whole-genome sequencing identified a genome size of 3.33 Mbp with 3353 coding genes. Digital DNA–DNA hybridization (dDDH) and average nucleotide identity (ANI) analyses confirmed Bos-x6-28 as a novel species, hereby named B. maqinnsis Bos-x6-28 (MCCC 1K09379). Further genomic analysis unveiled biosynthetic gene clusters encoding bioactive natural compounds, including β-lactones, sactipeptides, fengycin, and lichenysin analogs. Additionally, in vitro assays demonstrated that this strain exhibits antibacterial and cytotoxic activities. Conclusions: These findings collectively indicate the novel Bacillus species B. maqinnsis Bos-x6-28 as a promising source for novel antibiotic and antitumor agents. Full article

(This article belongs to the Special Issue Antimicrobial and Anti-Infective Activity of Natural Products, 2nd Edition)

► Show Figures

Figure 1

Figure 1
Phylogenetic analysis of strain Bos-x6-28 based on 16S rRNA gene sequence using the neighbor-joining (NJ) method. The sequence numbers in parentheses represent the GenBank accession numbers of the corresponding strains. The scale bar indicates a 0.02 nucleotide divergence per site. Full article ">Figure 2
Microscopic structure of strain Bos-x6-28. (A) Scanning electron microscopy (SEM) at 20,000× magnification, showing the detailed ultrastructure of Bos-x6-28. (B) Light microscopy at 1000× magnification after Gram staining, illustrating cellular morphology and Gram characteristics. Full article ">Figure 3
Two-dimensional TLC analysis of phospholipid components in strain Bos-x6-28. (A) Ninhydrin staining; (B) Anisaldehyde staining; (C) Phosphomolybdic acid staining. Full article ">Figure 4
Circular genome map of strain Bos-x6-28. The outermost ring denotes the genomic size, with each tick mark representing 5 kb. The second and third rings display genes on the positive and negative strands, respectively, with different colors indicating various COG functional classifications. The fourth ring represents repeat sequences. The fifth ring shows tRNA (blue) and rRNA (purple) genes. The sixth ring illustrates GC content, where light yellow areas indicate regions with GC content higher than the genome’s average, with peak heights corresponding to the extent of deviation from the mean; blue areas denote regions with GC content below the genomic average. The innermost ring represents the GC-skew, with dark gray indicating regions where G content exceeds C content, and red indicating regions where C content exceeds G content. Full article ">Figure 5
Comparative genomic analysis of strain Bos-x6-28 and its closely related species. The outermost ring represents the strain origin and shared core gene clusters, followed by the geometric homogeneity index and functional homogeneity index. Subsequent rings display data for B. safensis subsp. safensis FO-36b, B. pumilus NCTC10337, B. australimaris NH7I-1, B. altitudinis 41KF2b, B. zhangzhouensis DW5-4, B. xiamenensis HYC-10, B. safensis subsp. osmophilus BC09, and Bos-x6-28. The heat map shows the ANI values among these strains, with all ANI values below 95% (indicated in pink), highlighting the genomic divergence among the strains. Full article ">Figure 6
Bioactivity of secondary metabolites from strain Bos-x6-28. (A) Inhibitory activity against B. subtilis, with ampicillin as a positive control and methanol as a negative control. (B) Inhibitory activity against human liver cancer cells (HepG2), using DMSO as the blank control. Data are presented as mean ± SD, derived from three independent experiments conducted in triplicate. Statistical significance is indicated as *** p < 0.001 compared to control cells, and **** p < 0.0001 compared to control cells (Wilcoxon t-test). Full article ">

20 pages, 3131 KiB

Open AccessArticle

Ellagic Acid Potentiates the Inhibitory Effects of Fluconazole Against Candida albicans

by Amanda Graziela Gonçalves Mendes, Carmem Duarte Lima Campos, José Lima Pereira-Filho, Aleania Polassa Almeida Pereira, Gabriel Silva Abrantes Reis, Árlon Wendel de Marinho Silva Araújo, Pablo de Matos Monteiro, Flávia Castello Branco Vidal, Silvio Gomes Monteiro, Isabella Fernandes da Silva Figueiredo, Elizabeth Soares Fernandes, Cristina de Andrade Monteiro and Valério Monteiro-Neto

Antibiotics 2024, 13(12), 1174; https://doi.org/10.3390/antibiotics13121174 - 4 Dec 2024

Viewed by 613

Abstract

Background/Objectives: Antifungal resistance to azoles, coupled with the increasing prevalence of Candida albicans infections, represents a significant public health challenge and has driven the search for new natural compounds that can act as alternatives or adjuvants to the current antifungals. Ellagic acid (EA) [...] Read more.

Background/Objectives: Antifungal resistance to azoles, coupled with the increasing prevalence of Candida albicans infections, represents a significant public health challenge and has driven the search for new natural compounds that can act as alternatives or adjuvants to the current antifungals. Ellagic acid (EA) has demonstrated antifungal activity; however, its effects are not fully understood. In this study, we investigated the in vitro anti-Candida activity of EA and its ability to potentiate the effects of fluconazole (FLZ) on C. albicans. Methods: The Minimum Inhibitory Concentration (MIC) of EA was determined by broth microdilution and its interaction with FLZ was assessed using a checkerboard assay. Additionally, we examined the effects of EA on yeast-to-hypha transition, inhibition of biofilm formation, time–kill kinetics, hemolytic activity, and cytotoxicity in HeLa ATCC^® CCL-2™ cells. Results: EA exhibited MIC values ranging from 250 to 2000 µg/mL and showed synergistic and additive interactions with FLZ, resulting in a marked reduction in the MIC values of FLZ (up to 32-fold) and EA (up to 16-fold). In the time–kill assay, the most effective combinations were 4× EA MIC, 2× EA MIC, and FIC EA + FLZ, which showed fungicidal activity. Furthermore, EA did not show hemolytic activity and demonstrated low and dose-dependent cytotoxicity in HeLa cells, with no cytotoxic effects observed in combination with FLZ. EA and the synergistic combination of EA and FLZ interfered with both the yeast-to-hypha transition process in C. albicans cells and biofilm formation. In addition to its antifungal efficacy, EA demonstrated a favorable safety profile at the concentrations used. Conclusions: This study presents promising results regarding the potential use of EA in combination with FLZ for the treatment of C. albicans infections. Full article

(This article belongs to the Special Issue Antimicrobial and Anti-Infective Activity of Natural Products, 2nd Edition)

► Show Figures

Figure 1

Figure 1
Time-kill curve of C. albicans ATCC 90028 under the action of EA (A) and FLZ (B) and their combination (FIC EA + FLZ) (C) showing the medians. The Shapiro–Wilk test was used to assess the normality of the sample. Significant differences between groups were determined by Kruskal–Wallis analysis followed by Dunn’s test with p > 0.05 considered significant. Legend: FIC = fractional inhibitory combination, MIC = minimal inhibitory concentration, EA = ellagic acid, FLZ = fluconazole. Full article ">Figure 2
Time-kill curve of C. albicans CA 08 under the action of EA (A), FLZ (B) and in combination (FIC EA + FLZ) (C), at different concentrations and control. The Shapiro–Wilk test was applied to analyze normality. Significant differences between groups were determined by Kruskal-Walli’s analysis followed by Dunn’s test, presenting the medians test with (p > 0.05) considered significant. Legend: FIC = fractional inhibitory combinations, MIC = minimal inhibitory concentration, EA = ellagic acid, FLZ = fluconazole. Full article ">Figure 3
C. albicans hyphae formation. Clinical isolates: (A) CA 90028; (B) CA 013; (C) CA 010; (D) CA08. The Shapiro–Wilk normality test was applied. The results are presented as mean and standard deviation; significant differences between groups were determined by one-way analysis of variance (ANOVA) followed by Tukey’s multiple comparison where the value of p < 0.05 (*) was considered significant. Full article ">Figure 4
Cell viability of young C. albicans biofilms. Clinical isolates: (A) CA 90028; (B) CA 013; (C) CA 010; (D) CA08. The Shapiro–Wilk normality test was applied. Results are presented as mean and standard deviation; significant differences between groups were determined by one-way analysis of variance (ANOVA) followed by Tukey’s multiple comparison where the value of p < 0.05 (*) was significant. Full article ">Figure 5
Cell viability of mature C. albicans biofilms. Clinical isolates: (A) CA 90028; (B) CA 013; (C) CA 010; (D) CA08. The Shapiro–Wilk normality test was applied. Significant differences between groups were determined by Kruskal–Wallis analysis of variance followed by Dunn’s test, where the value of p < 0.05 (*) was significant. Full article ">Figure 6
Hemolytic activity. The Shapiro–Wilk normality test was applied. The test results are presented with mean and standard deviation; significant differences between specific groups were determined by one-way analysis of variance (ANOVA) followed by Tukey’s multiple comparison, where the value of (* p < 0.05) was significant. Full article ">Figure 7
Cytotoxicity assay in HeLa. Cell viability was evaluated after (A) 24 h, (B) 48 h, and (C) 72 h. The Shapiro–Wilk normality test was applied. Significant differences between groups were determined by Kruskal–Wallis analysis followed by Dunn’s multiple comparisons test, where the value of (* p < 0.05) was significant. EA = ellagic acid; FLZ = fluconazole. Full article ">

23 pages, 6586 KiB

Open AccessArticle

Studies Regarding Antimicrobial Properties of Some Microbial Polyketides Derived from Monascus Strains

by Daniela Albisoru, Nicoleta Radu, Lucia Camelia Pirvu, Amalia Stefaniu, Narcisa Băbeanu, Rusandica Stoica and Dragos Paul Mihai

Antibiotics 2024, 13(11), 1092; https://doi.org/10.3390/antibiotics13111092 - 16 Nov 2024

Viewed by 1028

Abstract

Finding new molecules to prevent the growth of antimicrobial resistance is a hot topic for scientists worldwide. It has been reported that some raw bioproducts containing Monascus polyketides have antimicrobial activities, but extensive studies on this effect have not been conducted. In this [...] Read more.

Finding new molecules to prevent the growth of antimicrobial resistance is a hot topic for scientists worldwide. It has been reported that some raw bioproducts containing Monascus polyketides have antimicrobial activities, but extensive studies on this effect have not been conducted. In this context, our studies aimed to evaluate the antimicrobial properties of six raw bioproducts containing three classes of microbial polyketides biosynthesized by three Monascus strains through solid-state biosynthesis. As a methodology, we performed in silico predictions using programs such as PyMOL v3.0.4 and employed ESI-MS techniques to provide evidence of the presence of the six studied compounds in our bioproducts. The results obtained in silico were validated through in vitro studies using the Kirby-Bauer diffusion method on bacteria and fungi. The test performed in silico showed that Monascorubramine has the highest affinity for both Gram-positive and Gram-negative bacteria, followed by yellow polyketides such as Ankaflavin and Monascin. The estimated pharmacokinetic parameters indicated high gastrointestinal absorption and the potential to cross the blood-brain barrier for all studied compounds. However, the compounds also inhibit most enzymes involved in drug metabolism, presenting some level of toxicity. The best in vitro results were obtained for S. aureus, with an extract containing yellow Monascus polyketides. Predictions made for E. coli were validated in vitro for P. aeruginosa, S. enterica, and S. marcescens, as well as for fungi. Significant antibacterial properties were observed during this study for C. albicans, S. aureus, and fungal dermatophytes for crude bioproducts containing Monascus polyketides. In conclusion, the antimicrobial properties of Monascus polyketides were validated both in silico and in vitro. However, due to their potential toxicity, these bioproducts would be safer to use as topical formulations. Full article

(This article belongs to the Special Issue Antimicrobial and Anti-Infective Activity of Natural Products, 2nd Edition)

► Show Figures

Figure 1

15 pages, 3630 KiB

Open AccessArticle

Anti-Biofilm Action of Cineole and Hypericum perforatum to Combat Pneumonia-Causing Drug-Resistant P. aeruginosa

by Sourav Chakraborty, Piyush Baindara, Pralay Sharma, Austin Jose T, Kumaravel V, Raja Manoharan and Santi M. Mandal

Antibiotics 2024, 13(8), 689; https://doi.org/10.3390/antibiotics13080689 - 24 Jul 2024

Viewed by 1636

Abstract

Hospital-acquired antibiotic-resistant pneumonia is one of the major causes of mortality around the world that pose a catastrophic threat. Pseudomonas aeruginosa is one of the most significant opportunistic pathogens responsible for hospital-acquired pneumonia and gained resistance to the majority of conventional antibiotics. There [...] Read more.

Hospital-acquired antibiotic-resistant pneumonia is one of the major causes of mortality around the world that pose a catastrophic threat. Pseudomonas aeruginosa is one of the most significant opportunistic pathogens responsible for hospital-acquired pneumonia and gained resistance to the majority of conventional antibiotics. There is an urgent need for antibiotic alternatives to control drug-resistant pneumonia and other related respiratory infections. In the present study, we explored the antibacterial potential of cineole in combination with homeopathic medicines against biofilm-forming drug-resistant P. aeruginosa. Out of 26 selected and screened homeopathic medicines, Hypericum Perforatum (HyPer) was found to eradicate biofilm-forming drug-resistant P. aeruginosa most effectively when used in combination with cineole. Interestingly, the synergistic action of HyPer and cineole was also found to be similarly effective against planktonic cells of P. aeruginosa. Further, the potential synergistic killing mechanisms of cineole and HyPer were determined by analyzing zeta membrane potential, outer membrane permeability, and DNA release from P. aeruginosa cells upon treatment with cineole and HyPer. Additionally, molecular docking analysis revealed strong binding affinities of hypericin (an active ingredient of HyPer) with the PqsA (a quorum sensing protein) of P. aeruginosa. Overall, our findings revealed the potential synergistic action of cineole and HyPer against biofilm-forming drug-resistant P. aeruginosa. Cineole and HyPer could be used in combination with other bronchodilators as inhalers to control the biofilm-forming drug-resistant P. aeruginosa. Full article

(This article belongs to the Special Issue Antimicrobial and Anti-Infective Activity of Natural Products, 2nd Edition)

► Show Figures

Figure 1

Figure 1
Primary screening of 26 homeopathic medicines against drug-resistant P. aeruginosa. Hypericum perforatum displayed the highest anti-biofilm activity, represented in a maroon color bar. Error bars show a standard deviation (SD) while statistical significance is considered at the level of p < 0.05 (indicated as red stars above bar). The experiment was performed three times independently in triplicate. Full article ">Figure 2
Synergistic antibacterial activity of HyPer and cineole. (A) Well diffusion assay displaying the synergistic action of HyPer and cineole. Well numbers 1, 2, 3, 4, and 5 indicate 5 μL, 10 μL, 20 μL, 40 μL, and 60 μL of HyPer (30 CH), respectively, in combination with 125 μg/mL of Cn. Cn alone was used as a control. (B) MIC determination of HyPer in combination with 125 μg/mL of cineole. T1, T2, T3, T4, and T5 indicate 5 μL, 10 μL, 20 μL, 40 μL, and 60 μL of HyPer (30 CH), respectively, in combination with 125 μg/mL of Cn. P. aeruginosa treated with Cn alone and 30% ethanol in PBS (UT) were used as controls. Error bars show a standard deviation (SD) while statistical significance is considered at the level of p < 0.05 (indicated as red stars above bars). All experiments were performed three times independently in triplicate. Full article ">Figure 3
Membrane zeta potential of untreated and treated P. aeruginosa cells with cineole, HyPer, and a combination of both. P. aeruginosa treated with 30% ethanol in PBS was used as a control. Error bars show a standard deviation (SD) while statistical significance is considered at the level of p < 0.05 (indicated as red stars above bars). The experiment was performed three times independently in triplicate. Full article ">Figure 4
Outer membrane permeability of untreated and treated P. aeruginosa cells with cineole, HyPer, and a combination of both for different time points of treatment: (A) 1 h, (B) 2 h, and (C) 3 h. P. aeruginosa cells treated with 30% ethanol in PBS were used as a control. Error bars show a standard deviation (SD) while statistical significance is considered at the level of p < 0.05 (indicated as red stars). All experiments were performed three times independently in triplicate. Full article ">Figure 5
Intracellular leakage of untreated and treated P. aeruginosa cells with cineole, HyPer, and a combination of both for the time points of 0, 5, 10, 20, and 30 min. P. aeruginosa cells treated with 30% ethanol in PBS were used as a control. Error bars show a standard deviation (SD) while statistical significance is considered at the level of p < 0.05 (indicated as red stars). The experiment was performed three times independently in triplicate. Full article ">Figure 6
Molecular docking and interaction of cineole and hypericin with PqsA, a biofilm-forming protein of P. aeruginosa. (A) Docked complex of cineole and PqsA. The dotted red line circle highlights the position of cineole in the complex. (B) Three-dimensional representation of interacting amino acid residues of PqsA with cineole upon docking. (C) Docked complex of hypericin and PqsA. The dotted red line circle highlights the position of hypericin in the complex. (D) Three-dimensional representation of interacting amino acid residues of PqsA with hypercin upon docking. PqsA is shown as a yellow ribbon while cineole, hypercin, and interactive amino acid residues are shown as sticks. Interacting bonds are represented as dotted green, purple, and violet lines. Full article ">

17 pages, 3725 KiB

Open AccessArticle

Artemisinin May Disrupt Hyphae Formation by Suppressing Biofilm-Related Genes of Candida albicans: In Vitro and In Silico Approaches

by Esra Sumlu, Merve Aydin, Emine Nedime Korucu, Saliha Alyar and Ahmed Moustapha Nsangou

Antibiotics 2024, 13(4), 310; https://doi.org/10.3390/antibiotics13040310 - 28 Mar 2024

Cited by 1 | Viewed by 2403

Abstract

This study aimed to assess the antifungal and antibiofilm efficacy of artemisinin against Candida (C.) species, analyze its impact on gene expression levels within C. albicans biofilms, and investigate the molecular interactions through molecular docking. The antifungal efficacy of artemisinin on a variety [...] Read more.

This study aimed to assess the antifungal and antibiofilm efficacy of artemisinin against Candida (C.) species, analyze its impact on gene expression levels within C. albicans biofilms, and investigate the molecular interactions through molecular docking. The antifungal efficacy of artemisinin on a variety of Candida species, including fluconazole-resistant and -susceptible species, was evaluated by the microdilution method. The effect of artemisinin on C. albicans biofilm formation was investigated by MTT and FESEM. The mRNA expression of the genes related to biofilm was analyzed by qRT-PCR. In addition, molecular docking analysis was used to understand the interaction between artemisinin and C. albicans at the molecular level with RAS1-cAMP-EFG1 and EFG1-regulated genes. Artemisinin showed higher sensitivity against non-albicans Candida strains. Furthermore, artemisinin was strongly inhibitory against C. albicans biofilms at 640 µg/mL. Artemisinin downregulated adhesion-related genes ALS3, HWP1, and ECE1, hyphal development genes UME6 and HGC1, and hyphal CAMP-dependent protein kinase regulators CYR1, RAS1, and EFG1. Furthermore, molecular docking analysis revealed that artemisinin and EFG1 had the highest affinity, followed by UME6. FESEM analysis showed that the fluconazole- and artemisinin-treated groups exhibited a reduced hyphal network, unusual surface bulges, and the formation of pores on the cell surfaces. Our study suggests that artemisinin may have antifungal potential and showed a remarkable antibiofilm activity by significantly suppressing adhesion and hyphal development through interaction with key proteins involved in biofilm formation, such as EFG1. Full article

(This article belongs to the Special Issue Antimicrobial and Anti-Infective Activity of Natural Products, 2nd Edition)

► Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
Effect of artemisinin on the expression of biofilm-related genes in strain (a) 7A, (b) 66A, and (c) C. albicans ATCC 10231. 18S ribosomal RNA was used for normalization of gene expression levels. Values are expressed as mean ± SEM, * p < 0.05, significantly different from the control; # p < 0.05, significantly different from the fluconazole. Full article ">Figure 2
Molecular association of artemisinin with EFG1, UME6, HGC1, RAS1, CYR1, HWP1, ECE1, and ALS3 in C. albicans ATCC 10231. Each graph shows (A) molecular binding mode (dashed thick orange line, hydrogen bonds; unbound amino acids, steric interactions); (B) 3D interaction docked pose view (green area: active site); (C) two-dimensional representation of hydrogen bonds made by artemisinin and related protein. Full article ">Figure 2 Cont.
Molecular association of artemisinin with EFG1, UME6, HGC1, RAS1, CYR1, HWP1, ECE1, and ALS3 in C. albicans ATCC 10231. Each graph shows (A) molecular binding mode (dashed thick orange line, hydrogen bonds; unbound amino acids, steric interactions); (B) 3D interaction docked pose view (green area: active site); (C) two-dimensional representation of hydrogen bonds made by artemisinin and related protein. Full article ">Figure 3
(A) Molecular binding mode of EFG1 and FLC (dashed thick orange line, hydrogen bonds; unbound amino acids, steric interactions); (B) the 3D interaction docked pose view (green area: active site); (C) two-dimensional representation of hydrogen bonds made by FLC and EFG1. Full article ">Figure 4
Root mean square deviation (RMSD) values of genes–artemisinin. Full article ">Figure 5
FESEM images of C. albicans ATCC 10231 biofilms after control and 24 h exposure to artemisinin and fluconazole. (A–C). Untreated biofilm culture. (D–F). Biofilm culture treated with 640 μg/mL artemisinin. (G–I). Biofilm culture treated with 4 μg/mL fluconazole. Magnification scales of 500×, 2000×, and 50,000× were used for imaging. Arrows indicate unusual surfaces and pore formation. The frame shows the selected region. Full article ">

20 pages, 9595 KiB

Open AccessArticle

Antimicrobial Activity of Bacillus amyloliquefaciens BS4 against Gram-Negative Pathogenic Bacteria

by Ana Paula Palacios-Rodriguez, Abraham Espinoza-Culupú, Yerson Durán and Tito Sánchez-Rojas

Antibiotics 2024, 13(4), 304; https://doi.org/10.3390/antibiotics13040304 - 28 Mar 2024

Cited by 1 | Viewed by 2668

Abstract

Worldwide, bacterial resistance is one of the most severe public health problems. Currently, the failure of antibiotics to counteract superbugs highlights the need to search for new molecules with antimicrobial potential to combat them. The objective of this research was to evaluate the [...] Read more.

Worldwide, bacterial resistance is one of the most severe public health problems. Currently, the failure of antibiotics to counteract superbugs highlights the need to search for new molecules with antimicrobial potential to combat them. The objective of this research was to evaluate the antimicrobial activity of Bacillus amyloliquefaciens BS4 against Gram-negative bacteria. Thirty yeasts and thirty-two Bacillus isolates were tested following the agar well-diffusion method. Four Bacillus sp. strains (BS3, BS4, BS17, and BS21) showed antagonistic activity against E. coli ATCC 25922 using bacterial culture (BC) and the cell-free supernatant (CFS), where the BS4 strain stood out, showing inhibitory values of 20.50 ± 0.70 mm and 19.67 ± 0.58 mm for BC and CFS, respectively. The Bacillus sp. BS4 strain can produce antioxidant, non-hemolytic, and antimicrobial metabolites that exhibit activity against several microorganisms such as Salmonella enterica, Klebsiella pneumoniae, Shigella flexneri, Enterobacter aerogenes, Proteus vulgaris, Yersinia enterocolitica, Serratia marcescens, Aeromonas sp., Pseudomonas aeruginosa, Candida albicans, and Candida tropicalis. According to the characterization of the supernatant, the metabolites could be proteinaceous. The production of these metabolites is influenced by carbon and nitrogen sources. The most suitable medium to produce antimicrobial metabolites was TSB broth. The one-factor-at-a-time method was used to standardize parameters such as pH, agitation, temperature, carbon source, nitrogen source, and salts, resulting in the best conditions of pH 7, 150 rpm, 28 °C, starch (2.5 g/L), tryptone (20 g/L), and magnesium sulfate (0.2 g/L), respectively. Moreover, the co-culture was an excellent strategy to improve antimicrobial activity, achieving maximum antimicrobial activity with an inhibition zone of 21.85 ± 1.03 mm. These findings position the Bacillus amyloliquefaciens BS4 strain as a promising candidate for producing bioactive molecules with potential applications in human health. Full article

(This article belongs to the Special Issue Antimicrobial and Anti-Infective Activity of Natural Products, 2nd Edition)

► Show Figures

Graphical abstract

Review

Jump to: Research

21 pages, 1602 KiB

Open AccessReview

A Comprehensive Review on the Antibacterial, Antifungal, Antiviral, and Antiparasitic Potential of Silybin

by José Lima Pereira-Filho, Amanda Graziela Gonçalves Mendes, Carmem Duarte Lima Campos, Israel Viegas Moreira, Cinara Regina Aragão Vieira Monteiro, Suzany Hellen da Silva Soczek, Elizabeth Soares Fernandes, Rafael Cardoso Carvalho and Valério Monteiro-Neto

Antibiotics 2024, 13(11), 1091; https://doi.org/10.3390/antibiotics13111091 - 15 Nov 2024

Viewed by 1383

Abstract

Silybin, a flavonolignan extracted from the seeds of the plant species Silybum marianum (L.) Gaertn., has a variety of pharmacological activities, including antimicrobial activity against several microorganisms of clinical interest. This review analyzes the existing studies on silybin’s antimicrobial activity and possible mechanisms [...] Read more.

Silybin, a flavonolignan extracted from the seeds of the plant species Silybum marianum (L.) Gaertn., has a variety of pharmacological activities, including antimicrobial activity against several microorganisms of clinical interest. This review analyzes the existing studies on silybin’s antimicrobial activity and possible mechanisms of action. Silybin has been shown to inhibit the growth of Gram-positive and Gram-negative bacteria, as well as some fungi, viruses, and protozoa. In general, possible mechanisms of antimicrobial action include the inhibition of efflux pumps, prevention of biofilm formation, reduction of the expression of virulence factors, induction of apoptosis-like effects, and plasma membrane damage, as well as the inhibition of nucleic acid and protein synthesis. Silybin has been shown to have synergistic effects when combined with conventional antibiotics against both drug-sensitive and drug-resistant microorganisms. However, the low bioavailability observed for this flavonolignan has been a challenge to its clinical use. In this context, nanotechnology has been used to increase silybin’s bioavailability while enhancing its antimicrobial activity. Furthermore, certain structural modifications have been able to enhance its antimicrobial activity in comparison to that of the natural molecule. Overall, this review provides insights into the scientific understanding of the mechanism of action of silybin and its desired properties for the effective treatment of infections. Full article

(This article belongs to the Special Issue Antimicrobial and Anti-Infective Activity of Natural Products, 2nd Edition)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Antimicrobial and Anti-Infective Activity of Natural Products, 2nd Edition

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Related Special Issue

Published Papers (8 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI