Whole-cell bioconversion for producing thymoquinone by engineered Saccharomyces cerevisiae

Thymoquinone, extracted from the black seeds of Nigella sativa, is a natural substance with highly beneficial effects against various human diseases. In this study, we aimed to construct a Saccharomyces cerevisiae strain that, produce thymoquinone from thymol, a relatively inexpensive substrate. To achieve this, cytochrome P450 from Origanum vulgare was expressed in S. cerevisiae for the bioconversion of thymol to thymoquinone, with the co-expression of cytochrome P450 reductase (CPR) from Arabidopsis thaliana, ATR1. Additionally, flexible linkers were used to connect these two enzymes. Furthermore, modifications were performed to expand the endoplasmic reticulum (ER) space, leading to increased thymoquinone production. After integrating the genes into the chromosome and optimizing the media components, a significant improvement in the thymol-to-thymoquinone conversion rate and yield were achieved. This study represents a possibility of the production of thymoquinone, a bioactive ingredient of a plant, using an engineered microbial cell.

Synthesis of homologous series of surfactants from renewable resources, structure-properties relationship, surface active performance, evaluation of their antimicrobial and anticancer potentialities

Sugar esters display surface-active properties, wetting, emulsifying, and other physicochemical phenomena following their amphipathic nature and recognize distinct biological activity. The development of nutritional pharmaceuticals and other applications remains of great interest. Herein, three novel homologous series of several N-mono-fatty acyl amino acid glucosyl esters were synthesized, and their physicochemical properties and biological activities were evaluated. The design and preparation of these esters were chemically performed via the reaction of glucose with different fatty acyl amino acids as renewable starting materials, with the suggestion that they would acquire functional characteristics superior and competitive to certain conventional surfactants. The synthesized products are characterized using FTIR, 1H-NMR, and 13C-NMR spectroscopy. Further, their physicochemical properties, such as HLB, CMC, Γmax, γCMC, and Amin, were determined. Additionally, their antimicrobial and anticancer efficiency were assessed. The results indicate that the esters' molecular structure, including the acyl chain length and the type of amino acid, significantly influences their properties. The measured HLB ranged from 8.84 to 12.27, suggesting their use as oil/water emulsifiers, wetting, and cleansing agents. All esters demonstrate promising surface-active characteristics, with moderate to high foam production with good stability. Notably, compounds 6-O-(N-dodecanoyl, tetradecanoyl cysteine)-glucopyranose (34, 35), respectively and 6-O-(N-12-hydroxy-9-octadecenoyl cysteine)-glucopyranose (38) display superior foamability. Wetting efficiency increased with decreasing the chain length of the acyl group. The storage results reveal that increasing the fatty acyl hydrophobe length enhances the derived emulsion's stability for up to 63 days. Particularly, including cysteine in these glucosyl esters improves wetting, foaming, and emulsifying potentialities. Furthermore, the esters exhibit antibacterial activity against several tested Gram-positive and Gram-negative bacteria and fungi. On the other hand, they show significant antiproliferative effects on some liver tumor cell lines. For instance, compounds 6-O-(N-12-hydroxy-9-octadecenoylglycine)-glucopyranose (28), 6-O-(N-dodecanoyl, hexadecanoyl, 9-octadecenoyl and 12-hydroxy-9-octadecenoylvaline)- glucopyranose (29, 31, 32 and 33), respectively in addition to the dodecanoyl, hexadecanoyl, 9-octadecenoyl and 12-hydroxy-9-octadecenoyl cysteine glucopyranose (34, 36, 37 and 38), respectively significantly inhibit the examined cancer cells.

Central Carbon Metabolism in Candida albicans Biofilms Is Altered by Dimethyl Sulfoxide

The effect of dimethyl sulfoxide (DMSO) on fungal metabolism has not been well studied. This study aimed to evaluate, by metabolomics, the impact of DMSO on the central carbon metabolism of Candida albicans. Biofilms of C. albicans SC5314 were grown on paper discs, using minimum mineral (MM) medium, in a dynamic continuous flow system. The two experimental conditions were control and 0.03% DMSO (v/v). After 72 h of incubation (37 °C), the biofilms were collected and the metabolites were extracted. The extracted metabolites were subjected to gas chromatography-mass spectrometry (GC/MS). The experiment was conducted using five replicates on three independent occasions. The GC/MS analysis identified 88 compounds. Among the 88 compounds, the levels of 27 compounds were markedly different between the two groups. The DMSO group exhibited enhanced levels of putrescine and glutathione and decreased levels of methionine and lysine. Additionally, the DMSO group exhibited alterations in 13 metabolic pathways involved in primary and secondary cellular metabolism. Among the 13 altered pathways, seven were downregulated and six were upregulated in the DMSO group. These results indicated a differential intracellular metabolic profile between the untreated and DMSO-treated biofilms. Hence, DMSO was demonstrated to affect the metabolic pathways of C. albicans. These results suggest that DMSO may influence the results of laboratory tests when it is used as a solvent. Hence, the use of DMSO as a solvent must be carefully considered in drug research, as the effect of the researched drugs may not be reliably translated into clinical practice.

Anticandidal Effect of New Imidazole Derivatives Over Aspartic Protease Inhibition

Candidiasis is one of the most serious microbial infections in the world. One of the main virulence factors for Candida albicans is the crucial secretion of aspartic proteases (Saps). Saps are hydrolytic enzymes that play a major role in many fungal pathophysiological processes as well as in many levels of the associations between the fungus and its host. In this work, we report on the synthesis, characterization, and anti-candida agent evaluation of a family of 13 imidazolidine-based aspartate protease inhibitors. In vitro and in silico enzyme inhibition studies have confirmed these compounds' ability to inhibit fungal aspartate protease. Based on the molecular mechanistic value scores from molecular docking and MD simulations, we selected the top compounds 5b (binding energy -13.90 kcal/mol) and 5m (binding energy -12.94 kcal/mol) from among 5a-l based on the molecular mechanistic value scores from molecular docking and MD simulations for use in in vitro validations. In the results, imidazolidine derivatives showed strong aspartic protease inhibition activity. In conclusion, compounds 5b and 5m were found as potent anti-candida agents and screened for further pre-clinical and clinical validations.

Green Chemistry and In silico Techniques for Synthesis of Novel Pyranopyrazole and Pyrazolo-pyrano-pyrimidine Derivatives as Promising Antifungal Agents

BACKGROUND

Every year Invasive Fungal Infections (IFI) are globally affecting millions of people. Candida albicans and Aspergillus niger have been reported as the most infectious and mortality-inducing fungal strains among all pathogenic fungi.

AIMS & OBJECTIVES

To tackle this problem in the current study Pyranopyrazoles and Pyrazolopyrano- pyrimidine derivatives were developed using molecular hybridization, green chemistry and one-pot multicomponent reaction.

MATERIALS AND METHODS

In the present work, New Chemical entities (NCE's) were developed on the basis of Structure activity relationship. All designed NCE's were screened for ADMET studies using the QikProp module of Schrodinger software. NCE's with zero violations were further docked on the crystal structure of 14α demethylase, cytochrome P450 and thymidine synthase (PDB ID: 5V5Z, 7SHI, 1BID). Selected molecules were synthesized using green chemistry techniques and evaluated for in vitro antifungal activity against Candida albicans and Aspergillus niger.

RESULTS AND DISCUSSION

Designed NCE's (B1-12 and C1-11) showed favorable results in ADMET studies. In the docking study six compounds from series-B and five molecules from series- C showed good dock score and binding interaction when compared with the standard drugs. Compounds B-3 and C-4 showed the highest zone of inhibition activity against Candida albicans, where as B-1 and C-3 had shown highest zone of inhibition activity against Aspergillus niger.

CONCLUSION

Bicyclic ring (series B) showed better activity as compare to fused tricyclic ring (series C).

Indonesian Euphorbiaceae: Ethnobotanical Survey, In Vitro Antibacterial, Antitumour Screening and Phytochemical Analysis of Euphorbia atoto

Indonesia is among the countries with the most significant biodiversity globally. Jamu, the traditional medicine of Indonesia, predominantly uses herbal materials and is an integral component of the Indonesian healthcare system. The present study reviewed the ethnobotanical data of seven Indonesian Euphorbiaceae species, namely Euphorbia atoto, E. hypericifolia, Homalanthus giganteus, Macaranga tanarius, Mallotus mollissimus, M. rufidulus, and Shirakiopsis indica, based on the RISTOJA database and other literature sources. An antimicrobial screening of the plant extracts was performed in 15 microorganisms using the disk diffusion and broth microdilution methods, and the antiproliferative effects were examined in drug-sensitive Colo 205 and resistant Colo 320 cells by the MTT assay. The antimicrobial testing showed a high potency of M. tanarius, H. giganteus, M. rufidulus, S. indica, and E. atoto extracts (MIC = 12.5-500 µg/mL) against different bacteria. In the antitumour screening, remarkable activities (IC50 0.23-2.60 µg/mL) were demonstrated for the extracts of H. giganteus, M. rufidulus, S. indica, and E. atoto against Colo 205 cells. The n-hexane extract of E. atoto, with an IC50 value of 0.24 ± 0.06 µg/mL (Colo 205), was subjected to multistep chromatographic separation, and 24-methylene-cycloartan-3β-ol, jolkinolide E, tetra-tert-butyl-diphenyl ether, α-tocopherol, and β-sitosterol were isolated.

Drug Repurposing Approach in Developing New Furosemide Analogs as Antimicrobial Candidates and Anti-PBP: Design, Synthesis, and Molecular Docking

Multidrug-resistant microorganisms have become a global health problem, prompting research into new antimicrobials. Drug repurposing is a new technique in drug discovery used to improve drug development success. As a well-studied medication with a sulfonamide moiety, furosemide was chosen to study its antimicrobial effect on different microbial strains. In addition, a new family of furosemide analogs was investigated for their antimicrobial efficacy. According to the obtained results, the majority of the examined molecules exhibited potential antimicrobial activity. Compounds 3b and 4a had the best anti-MRSA results, with an MIC = 7.81 µg/mL. They also demonstrated potent anti-gram-negative activity against E. coli (MIC = 1.95 µg/mL and 3.91 µg/mL, respectively). A time-killing kinetics study against E. coli and MRSA showed bactericidal actions of 3b and 4a within 120-150 min. Moreover, an anti-PBP activity and an in vitro cytotoxicity evaluation were performed. Furosemide decreased the PBP2a levels in MRSA by 21.5% compared to the control. However, the furosemide analogs 3b and 4a demonstrated superior anti-PBP activity (55.9 and 57.1 % reduction in the expression of PBP2a, respectively). In addition, compound 4a was nearly nontoxic to normal WI-38 cells (IC₅₀ = 248.60 μg /mL) indicating its high safety profile. Finally, the ability of furosemide and compounds 3b and 4a to bind to the target PBP2a enzyme has also been supported by molecular docking research.

Antimicrobial Preservatives for Protein and Peptide Formulations: An Overview

Biological drugs intended for multi-dose application require the presence of antimicrobial preservatives to avoid microbial growth. As the presence of certain preservatives has been reported to increase protein and peptide particle formation, it is essential to choose a preservative compatible with the active pharmaceutical ingredient in addition to its preservation function. Thus, this review describes the current status of the use of antimicrobial preservatives in biologic formulations considering (i) appropriate preservatives for protein and peptide formulations, (ii) their physico-chemical properties, (iii) their in-/compatibilities with other excipients or packaging material, and (iv) their interactions with the biological compound. Further, (v) we present an overview of licensed protein and peptide formulations.

Antimicrobial activity of jambu mawar [Syzygium jambos (L.) Alston] leaf extract against foodborne pathogens and spoilage microorganisms

The present work evaluated the antimicrobial potential of the ethanolic extract of jambu mawar [Syzygium jambos (L.) Alston] leaves against various foodborne pathogens and spoilage microorganisms via the disc diffusion assay (DDS) and the time-kill curve assay. These microorganisms included bacteria (Klebsiella pneumoniae ATCC13773, Listeria monocytogenes ATCC19112, Proteus mirabilis ATCC21100, Pseudomonas aeruginosa ATCC9027, Staphylococcus aureus ATCC29737, and Vibrio parahaemolyticus ATCC17802), yeasts (Candida albicans ATCC10231, C. krusei ATCC32196, C. glabrata ATCC2001, and C. parapsilosis ATCC22019), and moulds (Aspergillus fumigatus ATCC26430, A. niger ATCC9029, Rhizopus oligosporus ATCC22959, and R. oryzae ATCC22580). The inhibition zone of DDA ranged from 7.00 ± 0.23 to 10.25 ± 0.29 mm. The minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal (MBC/MFC) of the ethanolic leaf extract were obtained at the concentrations of 0.01 to 2.50 and 0.01 to 5.00 mg/mL, respectively. The time-kill curve assay showed that except for P. mirabilis, other microorganisms were completely killed at MIC concentrations ranging from 0.5 to 4× MIC. In comparison, P. mirabilis showed a growth reduction of > 3 log10 CFU/mL for 4 h. Meanwhile, the conidial germination of A. fumigatus was fully inhibited at 0.5× MIC. Though not fully inhibited, the ethanolic leaf extract significantly reduced the conidial germination of A. niger, R. oryzae, and R. oligosporus to 7.0, 7.0, and 11.0%, respectively. Overall, the ethanolic leaf extract of S. jambos exhibited antimicrobial activity against foodborne pathogens and spoilage microorganisms.

Curcumin affects function of Hsp90 and drug efflux pump of Candida albicans

Candida albicans is a pathogenic yeast that causes candidiasis in immunocompromised patients. The overuse of antifungal drugs has led to the development of resistance to such drugs by this fungus, which is a major challenge in antifungal chemotherapy. One approach to this problem involves the utilization of new natural products as an alternative source of antifungals. Curcumin, one such natural product, has been widely studied as a drug candidate and is reported to exhibit antifungal activity against C. albicans. Although studies of the mechanism of curcumin against human cancer cells have shown that it inhibits heat shock protein 90 (Hsp90), little is known about its function against C. albicans. In this paper, using a doxycycline-mediated HSP90 strain and an HSP90-overexpressing strain of C. albicans, we demonstrated that the curcumin triggered a decrease in Hsp90 by affecting it at the post-transcriptional level. This also led to the downregulation of HOG1 and CDR1, resulting in a reduction of the stress response and efflux pump activity of C. albicans. However, the inhibition of HSP90 by curcumin was not due to the inhibition of transcription factors HSF1 or AHR1. We also found that curcumin can not only decrease the transcriptional expression of CDR1, but also inhibit the efflux pump activity of Cdr1. Hence, we conclude that disruption of HSP90 by curcumin could impair cell growth, stress responses and efflux pump activity of C. albicans.

Chemical Composition, Enantiomeric Distribution, Antimicrobial and Antioxidant Activities of Origanum majorana L. Essential Oil from Nepal

This study was conducted to examine the chemical constituents of Origanum majorana L. essential oils (EOs) that originate in Nepal, as well as their biological activities, antioxidant properties, and enantiomeric compositions. The EOs were extracted by the hydro-distillation method using a Clevenger-type apparatus and their chemical compositions were determined through gas chromatography and mass spectrometry (GC-MS). Chiral GC-MS was used to evaluate the enantiomeric compositions of EOs. The minimum inhibitory concentrations (MICs) of the essential oils were determined by the micro-broth dilution method, and the antioxidant activity was evaluated by the 2,2-diphenyl-1-picrylhydrazyl scavenging assay and ferric-reducing antioxidant power (FRAP). GC-MS analysis showed the presence of 50 and 41 compounds in the EO samples, (S₁) and (S₂), respectively, representing the Kathmandu and Bhaktapur districts. The oxygenated monoterpenoids, along with terpinen-4-ol, were predominant constituents in both EO samples. However, the EOs from two locations showed some variations in their major components. The chiral terpenoids for two EO samples of marjoram have also been reported in this study in an elaborative way for the first time in accordance with the literature review. A hierarchical cluster analysis based on the compositions of EOs with 50 compositions reported in the literature revealed at least 5 different chemotypes of marjoram oil. The antioxidant activity for the sample (S₂) was found to be relatively moderate, with an IC₅₀ value of 225.61 ± 0.05 μg/mL and an EC₅₀ value of 372.72 ± 0.84 µg/mL, as compared to the standard used. Furthermore, with an MIC value of 78.1 µg/mL, the EO from sample (S₂) demonstrated effective antifungal activity against Aspergillus niger and Candida albicans. Moreover, both samples displayed considerable antimicrobial activity. The results suggest that EOs of Origanum majorana possess some noteworthy antimicrobial properties as well as antioxidant activity, and hence can be used as a natural preservative ingredient in the food and pharmaceutical industries.

Mechanism of Antifungal Action of Monoterpene Isoespintanol against Clinical Isolates of Candida tropicalis

The growing increase in infections by Candida spp., non-albicans, coupled with expressed drug resistance and high mortality, especially in immunocompromised patients, have made candidemia a great challenge. The efficacy of compounds of plant origin with antifungal potential has recently been reported as an alternative to be used. Our objective was to evaluate the mechanism of the antifungal action of isoespintanol (ISO) against clinical isolates of Candida tropicalis. Microdilution assays revealed fungal growth inhibition, showing minimum inhibitory concentration (MIC) values between 326.6 and 500 µg/mL. The eradication of mature biofilms by ISO was between 20.3 and 25.8% after 1 h of exposure, being in all cases higher than the effect caused by amphotericin B (AFB), with values between 7.2 and 12.4%. Flow cytometry showed changes in the permeability of the plasma membrane, causing loss of intracellular material and osmotic balance; transmission electron microscopy (TEM) confirmed the damage to the integrity of the plasma membrane. Furthermore, ISO induced the production of intracellular reactive oxygen species (iROS). This indicates that the antifungal action of ISO is associated with damage to membrane integrity and the induction of iROS production, causing cell death.

Liposomal Delivery of Newly Identified Prophage Lysins in a Pseudomonas aeruginosa Model

Pseudomonas aeruginosa is a Gram-negative opportunistic bacterium that presents resistance to several antibiotics, thus, representing a major threat to human and animal health. Phage-derived products, namely lysins, or peptidoglycan-hydrolyzing enzymes, can be an effective weapon against antibiotic-resistant bacteria. Whereas in Gram-positive bacteria, lysis from without is facilitated by the exposed peptidoglycan layer, this is not possible in the outer membrane-protected peptidoglycan of Gram-negative bacteria. Here, we suggest the encapsulation of lysins in liposomes as a delivery system against Gram-negative bacteria, using the model of P. aeruginosa. Bioinformatic analysis allowed for the identification of 38 distinct complete prophages within 66 P. aeruginosa genomes (16 of which newly sequenced) and led to the identification of 19 lysins of diverse sequence and function, 5 of which proceeded to wet lab analysis. The four purifiable lysins showed hydrolytic activity against Gram-positive bacterial lawns and, on zymogram assays, constituted of autoclaved P. aeruginosa cells. Additionally, lysins Pa7 and Pa119 combined with an outer membrane permeabilizer showed activity against P. aeruginosa cells. These two lysins were successfully encapsulated in DPPC:DOPE:CHEMS (molar ratio 4:4:2) liposomes with an average encapsulation efficiency of 33.33% and 32.30%, respectively. The application of the encapsulated lysins to the model P. aeruginosa led to a reduction in cell viability and resulted in cell lysis as observed in MTT cell viability assays and electron microscopy. In sum, we report here that prophages may be important sources of new enzybiotics, with prophage lysins showing high diversity and activity. In addition, these enzybiotics following their incorporation in liposomes were able to potentiate their antibacterial effect against the Gram-negative bacteria P. aeruginosa, used as the model.

Trans-Cinnamaldehyde Eluting Porous Silicon Microparticles Mitigate Cariogenic Biofilms

Dental caries, a preventable disease, is caused by highly-adherent, acid-producing biofilms composed of bacteria and yeasts. Current caries-preventive approaches are ineffective in controlling biofilm development. Recent studies demonstrate definite advantages in using natural compounds such as trans-cinnamaldehyde in thwarting biofilm assembly, and yet, the remarkable difficulty in delivering such hydrophobic bioactive molecules prevents further development. To address this critical challenge, we have developed an innovative platform composed of components with a proven track record of safety. We fabricated and thoroughly characterised porous silicon (pSi) microparticles to carry and deliver the natural phenyl propanoid trans-cinnamaldehyde (TC). We investigated its effects on preventing the development of cross-kingdom biofilms (Streptococcus mutans and Candida albicans), typical of dental caries found in children. The prepared pSi microparticles were roughly cubic in structure with 70–75% porosity, to which the TC (pSi-TC) was loaded with about 45% efficiency. The pSi-TC particles exhibited a controlled release of the cargo over a 14-day period. Notably, pSi-TC significantly inhibited biofilms, specifically downregulating the glucan synthesis pathways, leading to reduced adhesion to the substrate. Acid production, a vital virulent trait for caries development, was also hindered by pSi-TC. This pioneering study highlights the potential to develop the novel pSi-TC as a dental caries-preventive material.

Volatile Constituent Analysis of Wintergreen Essential Oil and Comparison with Synthetic Methyl Salicylate for Authentication

A comparative analysis of Gaultheria fragrantissima (Ericaceae) essential oils based on geographical location, distillation time, and varying distillation conditions was carried out, and their compositions were evaluated by gas chromatography-mass spectrometry (GC-MS), chiral GC-MS, and gas chromatography-flame ionization detection (GC-FID). In addition, each of seven commercial wintergreen essential oil samples from Nepal and China were analyzed. The highest extraction yield was 1.48% and the maximum number of compounds identified in natural wintergreen oil was twenty-two. Based on distillation time, the maximum numbers of identified compounds are present in 120 min. Linalool, phenol, vetispirane, and ethyl salicylate were present in commercial wintergreen oils both from Nepal and China. The presence of compounds such as elsholtzia ketone and β-dehydroelsholtzia ketone in the China samples represented a significant difference in wintergreen oil between the two geographical sources. Dimethyl 2-hydroxyterephthalate is a well-known synthetic marker for wintergreen oil when synthesis is carried out using salicylic acid, but the synthetic marker was absent while using acetylsalicylic acid as a precursor during synthesis. Adulteration analysis of wintergreen oil showed an increase in the concentration of dimethyl 2-hydroxyterephthalate, whereas the concentrations of minor components decreased and methyl salicylate remained unchanged. To the best of our knowledge, this is the first report of the enantioselective analysis of wintergreen essential oil. Furthermore, three samples showed notable antibacterial activity against Staphylococcus epidermidis, with an MIC value of 156.3 μg/mL. Similarly, one sample showed effectiveness against Aspergillus niger (MIC = 78.1 μg/mL).

Substitution to Position Number 2 of 4(3H)-Quinazolinone to Create New Derivatives and to Test the Antibacterial or Antifungal Effects

The campaign “No action today, no cure tomorrow” against antimicrobial resistance proposed by the World Health Organization (WHO) has not only propeled people to take action to prevent antimicrobial resistance, but has also encouraged researchers to develop new antimicrobial agents. 4(3H)-quinazolinone and its derivatives belong to a group of compounds with many potential applications; this study was conducted to find new derivatives of heterocyclic 4(3H)-quinazolinone with biological effects, contributing to research on antibacterial and antifungal compounds. Using the closed-loop method between anthranilic acid and acetic anhydride, followed by reaction with aniline derivatives, a substituted product of position 3 of 4(3H)-quinazolinone was obtained, along with bromizing to replace the hydrogen of the methyl group in position 2 with dibromo. Heterocyclic derivatives such as imidazole, triazole, and thiazole were replaced from this dibromo product to obtain 19 derivatives. The structures of these derivatives were checked by modern methods such as IR, 1H-NMR, and MS. The results indicated that all of the structures were as expected, so the process of creating new derivatives from 4(3H)-quinazolinone was achieved in this study. Fourteen of the derivatives, namely 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k, 3m, 3o, 3p, 3q, 3r, and 3s, had antibacterial or antifungal effects. Among these, there were five potential derivatives: Antifungal activity was observed on A. niger by 3j and 3f (MIC: 32 μg/mL) and 3s (MIC: 64 μg/mL), and on C. albicans by 3f (MIC: 8 μg/mL); antibacterial activity was observed on S. aureus by 3p (MIC: 16 μg/mL) and 3f and 3r (MIC: 32 μg/mL), on MRSA by 3f and 3r (MIC: 32 μg/mL), and on E. coli by 3f (MIC: 32 μg/mL).

Quality Assessment of Zingiber officinale Roscoe Essential Oil from Nepal

Zingiber officinale Roscoe rhizome plays a vital role in food flavoring as well as utilization in folk medicine. Nepal is categorized among the leading countries of Z. officinale rhizome production and export. Mature Z. officinale rhizome collection is based on the major production sites within Nepal, but we are currently unaware of the chemical composition of essential oil for export. A comparative investigation of Z. officinale rhizome essential oil compositions, collected from 12 different sites of the eastern, mid, and western regions of Nepal, has been carried out. The analysis of essential oils chemical composition by gas chromatographic–mass spectral (GC-MS), enantiomeric composition by chiral gas chromatography–mass spectrometry (CGC-MS), and antimicrobial activity was evaluated. Essential oil yields ranged from 0.28% to 0.34%. The results showed that the essential oils obtained in this study contained α-zingiberene (8.6%-24.1%), camphene (7.2%-12.8%), β-phellandrene (3.8%-10.1%), neral (0.6%-11.8%), geranial (1.0%-17.4%), ar-curcumene (3.0%-10.3%), and β-sesquiphellandrene (3.7%-9.7%). With CGC-MS, the enantiomeric distributions of 21 chiral compounds were determined and showed no contrasting enantiomeric distributions. Two essential oil samples (G3 and G5) possessed good antibacterial activity against Pseudomonas aeruginosa (MIC = 78.1μg/mL) and excellent antifungal activity against Aspergillus niger (MIC = 39.1 μg/mL). Based on the content of α-zingiberene and citral (neral and geranial), samples collected from their respective areas might be used to identify an ideal Z. officinale rhizome production zone in Nepal.

In vitro antibacterial and antifungal activities of extracts and fractions of leaves of Ricinus communis Linn against selected pathogens

INTRODUCTION

Infectious disease impacts are reduced due to the development of antimicrobial agents. However, the effectiveness of antimicrobial agents is reduced over time because of the emergence of antimicrobial resistance. To overcome these problems, scholars have been searching for alternative medicines. Ricinus communis is used as a traditional treatment for bovine mastitis, wound infection, and other medicinal purposes.

OBJECTIVE

The objective of the present study was to further evaluate the antimicrobial activities of R. communis leaf extracts and fractions.

METHODS

R. communis leaves were macerated in methanol and acetone. The methanol extract showed better antimicrobial activity and subjected to further fractionation via increasing polarity of solvents (n-hexane, chloroform, ethyl acetate, and aqueous). Test microorganisms included in the study were six laboratory reference bacteria (Escherichia coli, Staphylococcus aureus, Streptococcus agalactiae, Kleibsella pneumoniae, Pseudomonas aeruginosa and Streptococcus pyogenes), two clinical isolate bacteria (E. coli and S. aureus), and Candida albicans. The agar well diffusion method was employed to determine antimicrobial activity. The minimum inhibitory concentrations (MIC) and minimum bactericidal/fungicidal concentrations (MBC/MFC) were determined through broth microdilution.

RESULTS

The results indicated that the best antimicrobial activity for ethyl acetate fraction ranged from 14.67 mm (clinical E. coli) to 20.33 mm (S. aureus) at 400 mg/ml, however, n-hexane exhibited the lowest antimicrobial activity. Among the tested fractions, ethyl acetate fraction showed the lowest MIC values ranged from 1.5625 mg/ml (S. aureus) to 16.67 mg/ml (Candida albicans). The ethyl acetate fraction showed bactericidal activity against all tested microorganisms.

CONCLUSION

Hence, ethyl acetate fraction of crude methanol extract exhibited the best antimicrobial activity.

Chicory Extracts and Sesquiterpene Lactones Show Potent Activity against Bacterial and Fungal Pathogens

Chicory (Cichorium intybus L.) is an important industrial crop cultivated mainly to extract the dietary fiber inulin. However, chicory also contains bioactive compounds such as sesquiterpene lactones and certain polyphenols, which are currently discarded as waste. Plants are an important source of active pharmaceutical ingredients, including novel antimicrobials that are urgently needed due to the global spread of drug-resistant bacteria and fungi. Here, we tested different extracts of chicory for a range of bioactivities, including antimicrobial, antifungal and cytotoxicity assays. Antibacterial and antifungal activities were generally more potent in ethyl acetate extracts compared to water extracts, whereas supercritical fluid extracts showed the broadest range of bioactivities in our assays. Remarkably, the chicory supercritical fluid extract and a purified fraction thereof inhibited both methicillin-resistant Staphylococcus aureus (MRSA) and ampicillin-resistant Pseudomonas aeruginosa IBRS P001. Chicory extracts also showed higher antibiofilm activity against the yeast Candida albicans than standard sesquiterpene lactone compounds. The cytotoxicity of the extracts was generally low. Our results may thus lead to the development of novel antibacterial and antifungal preparations that are both effective and safe for human use.

Development of an Antibiotic Resistance Breaker to Resensitize Drug-Resistant Staphylococcus aureus: In Silico and In Vitro Approach

Efflux pumps are one of the predominant microbial resistant mechanisms leading to the development of multidrug resistance. In Staphylococcus aureus, overexpression of NorA protein enables the efflux of antibiotics belonging to the class of fluoroquinolones and, thus, makes S. aureus resistant. Hence, NorA efflux pumps are being extensively exploited as the potential drug target to evade bacterial resistance and resensitize bacteria to the existing antibiotics. Although several molecules are reported to inhibit NorA efflux pump effectively, boronic acid derivatives were shown to have promising NorA efflux pump inhibition. In this regard, the current study exploits 6-(3-phenylpropoxy)pyridine-3-boronic acid to further improve the activity and reduce cytotoxicity using the bioisostere approach, a classical medicinal chemistry concept. Using the SWISS-Bioisostere online tool, from the parent compound, 42 compounds were obtained upon the replacement of the boronic acid. The 42 compounds were docked with modeled NorA protein, and key molecular interactions of the prominent compounds were assessed. The top hit compounds were further analyzed for their drug-like properties using ADMET studies. The identified potent lead, 5-nitro-2-(3-phenylpropoxy)pyridine (5-NPPP), was synthesized, and in vitro efficacy studies have been proven to show enhanced efflux inhibition, thus acting as a potent antibiotic breaker to resensitize S. aureus without elucidating any cytotoxic effect to the host Hep-G2 cell lines.

The Chemical Profiling of Essential Oils from Different Tissues of Cinnamomum camphora L. and Their Antimicrobial Activities

Cinnamomum camphora L. is grown as an ornamental plant, used as raw material for furniture, as a source of camphor, and its essential oil can be used as an important source for perfume as well as alternative medicine. A comparative investigation of essential oil compositions and antimicrobial activities of different tissues of C. camphora was carried out. The essential oils were extracted by hydrodistillation with a Clevenger apparatus and their compositions were evaluated through gas chromatography-mass spectrometry (GC-MS), enantiomeric composition by chiral GC-MS, and antimicrobial properties were assayed by measuring minimum inhibitory concentrations (MICs). Different plant tissues had different extraction yields, with the leaf having the highest yield. GC-MS analysis revealed the presence of 18, 75, 87, 67, 67, and 74 compounds in leaf, branch, wood, root, leaf/branch, and leaf/branch/wood, respectively. The significance of combining tissues is to enable extraction of commercial quality essential oils without the need to separate them. The oxygenated monoterpene camphor was the major component in all tissues of C. camphora except for safrole in the root. With chiral GC-MS, the enantiomeric distributions of 12, 12, 13, 14, and 14 chiral compounds in branch, wood, root, leaf/branch, and leaf/branch/wood, respectively, were determined. The variation in composition and enantiomeric distribution in the different tissues of C. camphora may be attributed to the different defense requirements of these tissues. The wood essential oil showed effective antibacterial activity against Serratia marcescens with an MIC of 39.1 μg/mL. Similarly, the mixture of leaf/branch/wood essential oils displayed good antifungal activity against Aspergillus niger and Aspergillus fumigatus while the leaf essential oil was notably active against Trichophyton rubrum. C. camphora essential oils showed variable antimicrobial activities against dermal and pulmonary-borne microbes.

Antibiotic Resistance Characterization of Bacteria Isolated from Traditional Chinese Paocai

In this work, the antibiotic resistance of 218 isolates to 9 different antibiotics was analyzed with minimum inhibitory concentration method. All Lactobacillus pentosus strains were found to be resistant to streptomycin sulfate and ciprofloxacin hydrochloride. Lactococcus lactis strains were resistant to streptomycin sulfate. Specifically, 90% Klebsiella oxytoca and all Citrobacter freundii strains were resistant to ampicillin sodium. 30% K. oxytoca strains were resistant to ciprofloxacin hydrochloride. All Bacillus albus strains were resistant to erythromycin and 80% strains were resistant to ampicillin sodium. Results from PCR analysis revealed that 90 isolates carried the aadE gene. The tetM gene was detected in four L. pentosus isolates. And the streptomycin resistant gene aadA was detected in one L. pentosus isolate. Metagenome analysis revealed that 74.7% genes associated with antibiotic resistance were antibiotic resistance genes. The tetM and aadA genes, detected in PCR analysis, were also retrieved from the paocai metagenome. In brief, this study generated the antibiotic resistance profile of some paocai-originated bacteria strains. L. pentosus found in the final edible paocai were inherently resistant to antibiotics, such as streptomycin and ciprofloxacin. Results in this work reminds us to carefully choose the LAB strains for traditional Chinese paocai production to avoid potential spreading of antibiotic resistant genes.

Photorhabdus sp. ETL Antimicrobial Properties and Characterization of Its Secondary Metabolites by Gas Chromatography-Mass Spectrometry

Entomopathogenic nematodes (EPNs) are known to be highly pathogenic to insect pests, due to their associated symbiotic bacteria, which produce virulence factors, exo-enzymes and other harmful secondary metabolites to conquer, kill, and degrade their insect hosts. However, these properties are not fully characterized. This study reports on the antimicrobial activities of Photorhabdus sp. strain ETL, symbiotically associated to an insect pathogenic nematode, Heterorhabditis zealandica, against human pathogenic bacteria and toxigenic fungi, as well as the non-targeted profiling of its secondary metabolites (SMs) using gas chromatography coupled to high-resolution time-of-flight mass spectrometry. Fatty acids including 3-eicosene, (E)-; 5-eicosene, (E)-; eicosene; 9-octadecenamide; undecanoic acid with shown antimicrobial activities were detected. This provided more insight on the composition and bioactivities of SMs produced by the Photorhabdus sp.

Association of Macrolide Resistance Genotypes and Synergistic Antibiotic Combinations for Combating Macrolide-Resistant MRSA Recovered from Hospitalized Patients

Simple Summary

Macrolide-resistant methicillin-resistant Staphylococcus aureus (MAC-MRSA) is one of the most clinically relevant pathogens due to its significant ability of resistance acquisition to different antimicrobial agents and narrow therapeutic options. This study aimed to evaluate antimicrobial susceptibility and the use of different combinations of azithromycin with other antibiotics as well as studying the correlation of MAC resistance genotypes and antimicrobial agents that provided synergy when they were combined with azithromycin. Azithromycin (AZM) combinations with either linezolid, ceftriaxone, gentamicin, or cefotaxime provided synergy in 42.1%, 44.7%, 31.6% and 7.9% of the 38 MAC-MRSA isolates, respectively. Statistical analysis showed significant association between the presence of the ermA genotype and the synergism of AZM + ceftriaxone and AZM + gentamicin; the presence of the ermC genotype and the synergism between AZM and gentamicin; the presence of the msrA genotype and the synergism between AZM and ceftriaxone; and the presence of the ermA/msrA genotype and the synergism between AZM and cefotaxime. The obtained findings will guide clinicians in better choosing the antibiotic combinations required for combating MAC-MRSA clinical isolates. However, the promising synergistic antibiotic combinations must be re-evaluated in vivo using an appropriate animal model.

Abstract

Macrolide-resistant methicillin-resistant Staphylococcus aureus (MAC-MRSA) is one of the most clinically relevant pathogens due to its significant ability of resistance acquisition to different antimicrobial agents. This study aimed to evaluate antimicrobial susceptibility and the use of different combinations of azithromycin with other antibiotics for combating MAC resistance. Seventy-two Staphylococci (38.5%) (n = 187), showed resistance to MACs; of these, 53 isolates (73.6%, n = 72) were S. aureus and 19 (26.4%, n = 72) were coagulase-negative staphylococci (CoNS). Out of the 53 S. aureus and 19 CoNS isolates, 38 (71.7%, n = 53) and 9 (47.4%, n = 19) were MRSA and methicillin-resistant CoNS, respectively. The constitutive MACs, lincosamides and streptogramin-B (cMLS) comprised the predominant phenotype among S. aureus isolates (54.7%) and CoNS isolates (78.9%). The PCR analysis showed that the ermC gene was the most prevalent (79.2%), followed by msrA (48.6%), and ermA (31.9%). Azithromycin combinations with either linezolid, ceftriaxone, gentamicin, or cefotaxime provided synergy in 42.1%, 44.7%, 31.6% and 7.9% of the 38 MAC-MRSA isolates, respectively. Statistical analysis showed significant association between certain MAC resistance genotypes and the synergistic effect of certain azithromycin combinations (p value < 0.05). In conclusion, azithromycin combinations with either linezolid, or ceftriaxone showed synergism in most of the MAC-resistant MRSA clinical isolates.

Targeted Deletion of Los1 Homologue Affects the Production of a Recombinant Model Protein in Pichia pastoris

Background:

The methylotrophic yeast Pichia pastoris is an appealing production host for a variety of recombinant proteins, including biologics. In this sense, various genetic- and non-genetic-based techniques have been implemented to improve the production efficiency of this expression platform. Los1 (loss of supression) encodes a non-essential nuclear tRNA exporter in Saccharomyces cerevisiae, which its deletion extends RLS. Herein, a los1-deficient strain of P. pastoris was generated and characterized.

Methods:

A gene disruption cassette was prepared and transformed into an anti-CD22-expressing strain of P. pastoris. A δ los1 mutant was isolated and confirmed. The drug sensitivity of the mutant was also assessed. The growth pattern and the level of anti-CD22 ScFv expression were compared between the parent and mutant strains.

Results:

The los1 homologue was found to be a non-essential gene in P. pastoris. Furthermore, the susceptibility of los1 deletion strain to protein synthesis inhibitors was altered. This strain showed an approximately 1.85-fold increase in the extracellular level of anti-CD22 scFv (p < 0.05). The maximum concentrations of total proteins secreted by δ los1 and parent strains were 125 mg/L and 68 mg/L, respectively.

Conclusion:

The presented data suggest that the targeted disruption of los1 homologue in P. pastoris can result in a higher expression level of our target protein. Findings of this study may improve the current strategies used in optimizing the productivity of recombinant P. pastoris strains.

The Lack of SNARE Protein Homolog Syn8 Influences Biofilm Formation of Candida glabrata

Biofilm formation of Candida species is considered to be a pathogenic factor of host infection. Since biofilm formation of Candida glabrata has not been as well studied as that of Candida albicans, we performed genetic screening of C. glabrata, and three candidate genes associated with biofilm formation were identified. Candida glabrata SYN8 (CAGL0H06325g) was selected as the most induced gene in biofilm cells for further research. Our results indicated that the syn8Δ mutant was defective not only in biofilm metabolic activity but also in biofilm morphological structure and biomass. Deletion of SYN8 seemed to have no effect on extracellular matrix production, but it led to a notable decrease in adhesion ability during biofilm formation, which may be linked to the repression of two adhesin genes, EPA10 and EPA22. Furthermore, hypersensitivity to hygromycin B and various ions in addition to the abnormal vacuolar morphology in the syn8Δ mutant suggested that active vacuolar function is required for biofilm formation of C. glabrata. These findings enhance our understanding of biofilm formation in this fungus and provide information for the development of future clinical treatments.

Synthesis of Novel Stilbene-Coumarin Derivatives and Antifungal Screening of Monotes kerstingii-Specialized Metabolites Against Fusarium oxysporum

Fusarium is one of the most toxigenic phytopathogens causing diseases and reduced agricultural productivity worldwide. Current chemical fungicides exhibit toxicity against non-target organisms, triggering negative environmental impact, and are a danger to consumers. In order to explore the chemical diversity of plants for potential antifungal applications, crude extract and fractions from Monotes kerstingii were screened for their activity against two multi-resistant Fusarium oxysporum strains: Fo32931 and Fo4287. Antifungal activity was evaluated by the determination of minimum inhibitory concentration (MIC) by broth dilution of fermentative yeasts using kinetic OD_{600 nm} reading by a spectrophotometer. The n-butanol fraction showed the best activity against Fo4287. We screened eleven previously reported natural compounds isolated from different fractions, and a stilbene-coumarin 5-[(1E)-2-(4-hydroxyphenyl)ethenyl]-4,7-dimethoxy-3-methyl-2H-1-benzopyran-2-one (1) was the most active compound against both strains. Compound 1 was employed as a nucleophile with a selection of electrophilic derivatizing agents to synthesize five novel stilbene-coumarin analogues. These semisynthetic derivatives showed moderate activity against Fo32931 with only prenylated derivative exhibiting activity comparable to the natural stilbene-coumarin (1), demonstrating the key role of the phenolic group.

Myristica lowiana Phytochemicals as Inhibitor of Plasmid Conjugation in Escherichia coli

Hexane extract and methanol fraction from the stem bark of Myristica lowiana specifically and significantly inhibited the conjugal transfer of the IncW plasmid R7K, a plasmid which harbors ampicillin-, streptomycin-, and spectinomycin-resistant genes. The transfer of this plasmid via the conjugative pilli of Escherichia coli was reduced by 76.5 ± 2.0% and 79.0 ± 1.2% by hexane extract and methanol fraction of M. lowiana, respectively. The hexane extract exhibited significant anti-conjugant activity at a non-cytotoxic concentration of 100 mg/L as assessed against adult human dermal fibroblast cells. The hexane extract and methanol fraction were screened using phytochemical tests, NMR spectroscopy, IR spectroscopy, and high-resolution electrospray ionization mass spectrometry (HRESIMS) and were found to contain terpenoids, sterols, and fatty acids.

A Rapid and High Throughput MIC Determination Method to Screen Uranium Resistant Microorganisms

The assessment of minimum inhibitory concentration (MIC) is a conventional technique used for the screening of microbial resistance against antibiotics, biocides, and contaminants such as heavy metals. However, as part of our ongoing work, we have observed biases associated with using traditional liquid MIC method to screen microbial heavy metal resistance, including both bacterial and fungal strains. Specifically, the addition of uranium into synthetic media causes immediate precipitation prior to the initiation of microbial growth, thus hampering the optical density measurements, and the obtained MIC values are thus flawed and inaccurate. To address this discrepancy, we report the optimization and development of a serial-dilution-based MIC method conducted on solid growth media supplemented with uranium, which is more accurate, relative to the testing of MICs performed in liquid cultures. Notably, we report on the efficacy of this method to screen not only bacteria that are resistant to uranium but also demonstrate the successful application to yeast and fungal isolates, for their ability to resist uranium, is more accurate and sensitive relative to the liquid method. We believe that this newly developed method to screen heavy metal resistance, such as uranium, is far superior to the existing liquid MIC method and propose replacing the liquid assay with the solid plate MIC reported herein.

Antifungal peptides produced by actinomycetes and their biological activities against plant diseases

Antibacterial peptides are a class of naturally occurring peptides produced by eukaryotes and prokaryotes. Some of them exhibit broad-spectrum antifungal activity. Antifungal peptides (AFPs) can be developed as antibiotic to control fungal infections in agriculture due to their different antifungal mechanisms. As actinomycetes are still one of the most important sources of novel antibiotics, in this review, the mechanisms of action of AFPs are explained. Characterization of several AFPs produced by actinomycetes and their biological activities against plant diseases are summarized. Furthermore, the pathway for total synthesis of naturally occurring cyclodepsipeptide, valinomycin, is proposed. Finally, the pathway for biosynthesis of kutzneride 2 is proposed and the structure-activity relationship of kutznerides is discussed.

Elevated minimum inhibitory concentrations to antifungal drugs prevail in 14 rare species of candidemia-causing Saccharomycotina yeasts

Antifungal susceptibility profiles of rare Saccharomycotina yeasts remain missing, even though an increase in prevalence of such rare Candida species was reported in candidemia. Majority of these rare yeast species carry intrinsic resistances against at least one antifungal compound. Some species are known to be cross-resistant (against multiple drugs of the same drug class) or even multi-drug resistant (against multiple drugs of different drug classes). We performed antifungal susceptibility testing (AFST) according to EUCAST broth microdilution for 14 rare species (Clavispora lusitaniae, Candida intermedia, Candida auris, Diutina rugosa, Wickerhamiella pararugosa, Yarrowia lipolytica, Pichia norvegensis, Candida nivariensis, Kluyveromyces marxianus, Wickerhamomyces anomalus, Candida palmioleophila, Meyerozyma guilliermondii, Meyerozyma caribbica, and Debaryomyces hansenii) known to cause candidemia. In total, 234 isolates were tested for amphotericin B, fluconazole, itraconazole, voriconazole, posaconazole, anidulafungin, micafungin, and caspofungin. Amphothericin B had the broadest efficiency against the 14 tested rare yeast species, while high minimum inhibitory concentrations (MICs) against azole drugs and echinocandins were common. Voriconazole was the most efficient azole drug. Multidrug resistance was observed for the species C. auris and K. marxianus. Multidrug resistant individual isolates were found for Y. lipolytica and M. caribbica. In conclusion, the observed high MIC values of the rare Saccharomycotina species tested limit antifungal treatment options, complicating the management of such infections.

Induction of Cryptic Antifungal Pulicatin Derivatives from Pantoea agglomerans by Microbial Co-Culture

Microbial co-culture or mixed fermentation proved to be an efficient strategy to expand chemical diversity by the induction of cryptic biosynthetic pathways, and in many cases led to the production of new antimicrobial agents. In the current study, we report a rare example of the induction of silent/cryptic bacterial biosynthetic pathway by the co-culture of Durum wheat plant roots-associated bacterium Pantoea aggolomerans and date palm leaves-derived fungus Penicillium citrinum. The initial co-culture indicated a clear fungal growth inhibition which was confirmed by the promising antifungal activity of the co-culture total extract against Pc. LC-HRMS chemical profiling demonstrated a huge suppression in the production of secondary metabolites (SMs) of axenic cultures of both species with the emergence of new metabolites which were dereplicated as a series of siderophores. Large-scale co-culture fermentation led to the isolation of two new pulicatin derivatives together with six known metabolites which were characterised using HRESIMS and NMR analyses. During the in vitro antimicrobial evaluation of the isolated compounds, pulicatin H (2) exhibited the strongest antifungal activity against Pc, followed by aeruginaldehyde (1) and pulicatin F (4), hence explaining the initial growth suppression of Pc in the co-culture environment.

Incidence of Vancomycin Resistant Phenotype of the Methicillin Resistant Staphylococcus aureus Isolated from a Tertiary Care Hospital in Lahore

Staphylococcus aureus (S. aureus)-associated infections are one of the major threats to public health. The aim of the present study was to determine the antibiotic resistance pattern as well as the genetic characterization of methicillin and vancomycin resistant S. aureus (VRSA) isolated from a tertiary care hospital in Lahore. The S. aureus isolates were isolated from different clinical samples, identified by biochemical testing, and subjected to antibiotic susceptibility testing via the disc diffusion method or broth microdilution method. The methicillin resistance gene (mecA) and vancomycin resistance gene (vanA) were amplified by the polymerase chain reaction. The S. aureus isolates showed high incidences of resistance against methicillin (76%) and moderate incidences of resistance to vancomycin (14%). Isolates were also resistant to several other drugs, such as cefoxitin (76%), ertapenem (83%), ampicillin (81%), tobramycin (78%), moxifloxacin (76%), and tetracycline (74%). An encouraging finding was that 98% of isolates were susceptible to tigecycline, indicating its possible role in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) and VRSA, as well as the multi-drug resistant S. aureus. The mecA gene was detected in 33.3% of tested isolates (10/30), while the vanA gene was also detected in 30% (9/30) of the tested isolates. In conclusion, the frequent presence of methicillin and vancomycin resistance in S. aureus appraises the cautious use of these antibiotics in clinical practices. Furthermore, it is suggested that there should be continuous monitoring of tigecycline treatments in clinical setups in order to delay the development of resistance against it.

Antiviral, Antimicrobial and Antibiofilm Activity of Selenoesters and Selenoanhydrides

Selenoesters and the selenium isostere of phthalic anhydride are bioactive selenium compounds with a reported promising activity in cancer, both due to their cytotoxicity and capacity to reverse multidrug resistance. Herein we evaluate the antiviral, the biofilm inhibitory, the antibacterial and the antifungal activities of these compounds. The selenoanhydride and 7 out of the 10 selenoesters were especially potent antiviral agents in Vero cells infected with herpes simplex virus-2 (HSV-2). In addition, the tested selenium derivatives showed interesting antibiofilm activity against Staphylococcus aureus and Salmonella enterica serovar Typhimurium, as well as a moderate antifungal activity in resistant strains of Candida spp. They were inactive against anaerobes, which may indicate that the mechanism of action of these derivatives depends on the presence of oxygen. The capacity to inhibit the bacterial biofilm can be of particular interest in the treatment of nosocomial infections and in the coating of surfaces of prostheses. Finally, the potent antiviral activity observed converts these selenium derivatives into promising antiviral agents with potential medical applications.

Hydrophobic Control of the Bioactivity and Cytotoxicity of de Novo-Designed Antimicrobial Peptides

Antimicrobial peptides (AMPs) can target bacterial membranes and kill bacteria through membrane structural damage and cytoplasmic leakage. A group of surfactant-like cationic AMPs was developed from substitutions to selective amino acids in the general formula of G(IIKK)₃I-NH₂, (called G₃, a de novo AMP), to explore the correlation between AMP hydrophobicity and bioactivity. A threshold surface pressure over 12 mN/m was required to cause measurable antimicrobial activity and this corresponded to a critical AMP concentration. Greater surface activity exhibited stronger antimicrobial activity but had the drawback of worsening hemolytic activity. Small unilamellar vesicles (SUVs) with specific lipid compositions were used to model bacterial and host mammalian cell membranes by mimicking the main structural determinants of the charge and composition. Leakage from the SUVs of encapsulated carboxyfluorescein measured by fluorescence spectroscopy indicated a negative correlation between hydrophobicity and model membrane selectivity, consistent with measurements of the zeta potential that demonstrated the extent of AMP binding onto model SUV lipid bilayers. Experiments with model lipid membranes thus explained the trend of minimum inhibitory concentrations and selectivity measured from real cell systems and demonstrated the dominant influence of hydrophobicity. This work provides useful guidance for the improvement of the potency of AMPs via structural design, whilst taking due consideration of cytotoxicity.

Models for acne: A comprehensive study

Acne vulgaris (AV) is the familiar chronic skin ailment affecting most of the individuals. This multifarious, disease involves the bacterium gram-positive, anaerobic Propionibacterium acnes (P. acnes) which resides on skin microflora, and participated in acne inflammation and acne lesions. The object of this review is to discuss presently available in vitro, ex vivo, and in vivo models to evaluate the cosmetic formulations that are developed for dealing and prevention of acne formation. These various available models offer new chances for further research on biologically active materials, drugs & pharmaceutical as well as cosmetics for acne treatment.

Biological detoxification of Monascus purpureus pigments by heat-treated Saccharomyces cerevisiae

BACKGROUND

Today, there is an increasing concern about the consumption of synthetic colorants in food because of their possible health hazards. Monascus purpureus has attracted a great deal of attention as it produces various coloured pigments with high chemical stability, but it also produces citrinin, a secondary toxic metabolite, along with the pigments. This study aims to investigate the amount of pigment and citrinin reduction by different treatments with Saccharomyces cerevisiae such as heat treatment and suspension concentration.

RESULTS

The results indicated that the ability of S. cerevisiae regarding citrinin adsorption increased with increase of temperature and yeast concentration. The maximum extent of citrinin adsorption was related to heat treatment at 121 °C and a yeast concentration of 10⁵ cells mL^-1 , for which citrinin reduced from 4.43 mg L^-1 in control to 0.1 mg L^-1 . Heat treatment of 10³ cells mL^-1 suspension of S. cerevisiae cells at 50 °C, with 0.56 mg L^-1 citrinin remaining in the medium, showed the lowest ability for citrinin binding. The optimum absorbance of all red, orange and yellow pigments was observed for the heat treatment at 50 °C and yeast concentrations of 10³ and 10⁴ cells mL^-1 which was greater than that for the control.

CONCLUSIONS

We can conclude from this study that heat treatment with S. cerevisiae can be a useful way to reduce citrinin to below the standard limits. © 2019 Society of Chemical Industry.

Enzyme responsive copolymer micelles enhance the anti-biofilm efficacy of the antiseptic chlorhexidine

Staphylococcal biofilms cause many infectious diseases and are highly tolerant to the effects of antimicrobials; this is partly due to the biofilm matrix, which acts as a physical barrier retarding the penetration and reducing susceptibility to antimicrobials, thereby decreasing successful treatment outcomes. In this study, both single and mixed micellar systems based on poly vinyl caprolactam (PCL)-polyethylene glycol (PEG) copolymers were optimised for delivery of chlorhexidine (CHX) to S. aureus, MRSA and S. epidermidis biofilms and evaluated for their toxicity using Caenorhabditis elegans. The respective polyethylene glycol (PEG) and poly vinyl caprolactam (PCL) structural components promoted stealth properties and enzymatic responsive release of CHX inside biofilms, leading to significantly enhanced penetration (56%) compared with free CHX and improving the efficacy against Staphylococcus aureus biofilms grown on an artificial dermis (2.4 log reduction of CFU). Mixing Soluplus-based micelles with Solutol further enhanced the CHX penetration (71%) and promoted maximum reduction in biofilm biomass (>60%). Nematodes-based toxicity assay showed micelles with no lethal effects as indicated by their high survival rate (100%) after 72 h exposure. This study thus demonstrated that bio-responsive carriers can be designed to deliver a poorly water-soluble antimicrobial agent and advance the control of biofilm associated infections.

Isolation and Characterization of Two New Metabolites from the Sponge-Derived Fungus Aspergillus sp. LS34 by OSMAC Approach

The application of an OSMAC (One Strain-Many Compounds) approach on the sponge-derived fungus Aspergillus sp. LS34, using two different media including solid rice medium and potato dextrose broth (PDB) resulted in the isolation and identification of two new compounds, named asperspin A (1) and asperther A (2) along with seven known compounds 3–9. Compounds 1–5 were detected in fungal extracts from rice medium, while compounds 6–9 were isolated from PDB medium. Their structures were unambiguously characterized by HRESIMS and NMR spectroscopic data. The growth inhibitory activity of these compounds against four pathogenic bacteria (Vibrio parahaemolyticus, Vibrio harveyi, Escherichia coli, and Staphylococcus aureus) were evaluated. All the compounds were also tested for their cytotoxicity against seven cancer cell lines, including CCRF-CEM, K562, BGC823, AGS, HCT-116, MDA-MB-453, and COR-L23. Among them, compound 9 showed strong activity against CCRF-CEM and K562 cells with IC₅₀ values of 1.22 ± 0.05 µM and 10.58 ± 0.19 µM, respectively. Notably, compound 7 also showed pronounced activity against S. aureus with an MIC value of 3.54 µM.

2-Acryloyl-4,5-methylenedioxyphenol: A Small Molecule Endowed with Antidermatophytic Activity

Background:

Superficial fungal infections are the most common fungal diseases in humans, affecting more than 25% of the population worldwide.

Methods:

In the present study, we have investigated the activity of kakuol, a natural compound isolated from the rhizomes of Asarum sieboldii, and some analogues, against various dermatophytes and pharmacologically relevant yeasts.

Results:

One of the tested compounds, 2-acryloyl-4,5-methylenedioxyphenol, showed a broadspectrum activity against most of the fungal species assayed, resulting particularly effective against dermatophyte strains (MIC values in the range of 0.25-0.5 &#181;g/mL, two/four-fold lower than the positive control miconazole).

Conclusion:

The results suggest that this molecule can be considered a promising starting point for the development of new antifungal compounds.

Ordering selected Zn(II), Cu(II), Pd(II) and Co(III) complex compounds: their separately and combinedly antibacterial therapy and DNA-binding studies

In this study, four Co(III)-, Cu(II)-, Zn(II)- and Pd(II)-based potent antibacterial complexes of formula K₃[Co(ox)₃]·3H₂O (I), [Cu(phen)₂Cl]Cl·6.5H₂O (II), [Zn(phen)₃]Cl₂ (III) and [Pd(phen)₂](NO₃)₂ (IV) (where ox is oxalato and phen is 1,10-phenanthroline) were synthesized. They were characterized by elemental analysis, molar conductivity measurements, UV-vis, Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (¹H-NMR) techniques. These metal complexes were ordered in three combination series of I+II, I+II+III and I+II+III+IV. Antibacterial screening for each metal complex and their combinations against Gram-positive and Gram-negative bacteria revealed that all compounds were more potent antibacterial agents against the Gram-negative than those of the Gram-positive bacteria. The four metal complexes showed antibacterial activity in the order I > II > III > IV, and the activity of their combinations followed the order of I+II+III+IV > I+II+III > I+II. The DNA-binding properties of complex (I) and its three combinations were studied using electronic absorption and fluorescence (ethidium bromide displacement assay) spectroscopy. The results obtained indicated that all series interact effectively with calf thymus DNA (CT-DNA). The binding constant (K_b), the number of binding sites (n) and the Stern-Volmer constant (K_sv) were obtained based on the results of fluorescence measurements. The calculated thermodynamic parameters supported that hydrogen bonding and van der Waals forces play a major role in the association of each series of metal complexes with CT-DNA and follow the above-binding affinity order for the series. Communicated by Ramaswamy H. Sarma.

Lipid Membrane Interactions of the Cationic Antimicrobial Peptide Chimeras Melimine and Cys-Melimine

Melimine and its derivatives are synthetic chimeric antimicrobial agents based on protamine and melittin. The binding of solubilized melimine and its derivative, with a cysteine on N-terminus, (cys-melimine) on tethered bilayer lipid membranes (tBLMs) was examined using ac electrical impedance spectroscopy. The addition of melimine and cys-melimine initially increased membrane conduction, which subsequently falls over time. The results were obtained for tBLMs comprising zwitterionic phosphatidylcholine, anionic phosphatidylglycerol, or tBLMs made using purified lipids from Escherichia coli. The effect on conduction is more marked with the cysteine variant than the noncysteine variant. The variation in membrane conduction most probably arises from individual melimines inducing increased ionic permeability, which is then reduced as the melimines aggregate and phase-separate within the membrane. The actions of these antimicrobials are modeled in terms of altering the critical packing parameter (CPP) of the membranes. The variations in the peptide length of cys-melimine were compared with a truncated version of the peptide, cys-mel4. The results suggest that the smaller molecule impacts the membrane by a mechanism that increases the average CPP, reducing membrane conduction. Alternatively, an uncharged alanine-replacement version of melimine still produced an increase in membrane conduction, further supporting the CPP model of geometry-induced toroidal pore alterations. All the data were then compared to their antimicrobial effectiveness for the Gram-positive and Gram-negative strains of bacteria, and their fusogenic properties were examined using dynamic light scattering in 1-oleoyl-2-hydroxy- sn-glycero-3-phosphocholine lipid spheroids. We conclude that a degree of correlation exists between the antimicrobial effectiveness of the peptides studied here and their modulation of membrane conductivity.