Inhibition of Aspergillus fumigatus Biofilm and Cytotoxicity Study of Natural Compound Cis-9-Hexadecenal

Bioprospecting Endophytic Fungi of Forest Plants for Bioactive Metabolites with Antibacterial, Antifungal, and Antioxidant Potentials

The growing emergence of multi-drug resistant microbial strains has kept the scientific world searching for novel bioactive compounds with specific chemical characteristics. Accordingly, researchers have started exploring the understudied metabolites from endophytes as a new source of bioactive compounds. In this context, the current study was designed to evaluate the bioactive properties of endophytic fungi from the Mokrzański forest in Wrocław, Poland that have not yet been fully researched. Forty-three endophytic fungi were isolated from twelve distinct plants. Following their cultivation, fungal extracts were separately prepared from biomass and cell-free filtrates, and their antibacterial, antifungal (against human and plant pathogens), and antioxidant properties were examined. Five promising fungi after screening were identified to possess all of these activities. These strains and their respective plant hosts were Trichoderma harzianum BUK-T (Fagus sylvatica), Aspergillus ochraceus ROB-L1 (Robinia pseudoacacia), Chaetomium cochliodes KLON-L1, Fusarium tricinctum KLON-L2 (Acer platanoides), and Penicillium chrysogenum SOS-B2 (Pinus sylvestris). Moreover, gamma irradiation at several doses (Gy) was separately applied to the fungal cultures to study their effects on the recorded activities. Finally, compounds after preparative thin-layer chromatography fractionation of the five fungal strains were identified by GC-MS. These findings suggest that the isolated endophytic fungi could serve as novel sources of bioactive metabolites with antibacterial, antifungal, and antioxidant properties, potentially paving the way for future research and the development of new bioactive compounds.

Comprehensive in vitro evaluation of Indigofera hochstetteri Baker extract: Effect of chemicals in antimicrobial, anticancer, anti-inflammatory, and anti-diabetic activities

The study aimed to analyze the pharmacological properties of medicinal plant Indigofera hochstetteri Baker extracts. Preliminary phytochemical analysis revealed a diverse range of secondary metabolites present in it. TLC analysis detected numerous phytochemicals with varying Rf values, aiding in different solvent systems. GC-MS analysis revealed the presence of 29 bioactive compounds with diverse pharmacological activities, including anti-inflammatory, antioxidant, analgesic and antimicrobial properties. Antimicrobial effect of I. hochstetteri Baker methanolic extract showed significant inhibitory effects against E. coli, E. aerogenes, S. flexneri, P. aeruginosa, S. aureus, E. faecalis, B. cereus, and fungal strain C. albicans. The methanol extract also showed significant antifungal activity by inhibiting the growth of Sclerotium rolfsii in food poisoning method. MTT assays revealed significant cytotoxic activity of methanolic extract against human leukemia HL-60 cancer cells with IC50 of 116.01 μg/mL. In apoptotic study, I. hochstetteri Baker methanolic extract showed 28.84% viable cells, 30.2% early apoptosis, 35.54% late apoptosis, and 5.86% necrosis comparatively similar with standard used. The extract showed significant anti-inflammatory effect on HRBC stabilization, and protein denaturation of BSA and egg albumin denaturation with IC50 of 193.62 μg/mL, 113.94 μg/mL respectively. In anti-diabetic assays like α-amylase, α-glucosidase, and Glucose uptake assay, I. hochstetteri extract showed good anti-diabetic effect with IC50 of 60.64 μg/mL, 169.34 μg/mL, and 205.63 μg/mL respectively. In conclusion I. hochstetteri Baker have promising bioactive metabolites with significant biological activities, it can be good substitute for the chemical drugs after successful clinical studies.

cyp51A mutations, protein modeling, and efflux pump gene expression reveals multifactorial complexity towards understanding Aspergillus section Nigri azole resistance mechanism

Black Aspergillus species are the most common etiological agents of otomycosis, and pulmonary aspergillosis. However, limited data is available on their antifungal susceptibility profiles and associated resistance mechanisms. Here, we determined the azole susceptibility profiles of black Aspergillus species isolated from the Indian environment and explored the potential resistance mechanisms through cyp51A gene sequencing, protein homology modeling, and expression analysis of selected genes cyp51A, cyp51B, mdr1, and mfs based on their role in imparting resistance against antifungal drugs. In this study, we have isolated a total of 161 black aspergilli isolates from 174 agricultural soil samples. Isolates had variable resistance towards medical azoles; approximately 11.80%, 3.10%, and 1.24% of isolates were resistant to itraconazole (ITC), posaconazole (POS), and voriconazole (VRC), respectively. Further, cyp51A sequence analysis showed that non-synonymous mutations were present in 20 azole-resistant Aspergillus section Nigri and 10 susceptible isolates. However, Cyp51A homology modeling indicated insignificant protein structural variations because of these mutations. Most of the isolates showed the overexpression of mdr1, and mfs genes. Hence, the study concluded that azole-resistance in section Nigri cannot be attributed exclusively to the cyp51A gene mutation or its overexpression. However, overexpression of mdr1 and mfs genes may have a potential role in drug resistance.

Biofilm-mediated infections by multidrug-resistant microbes: a comprehensive exploration and forward perspectives

A biofilm is a collection of microorganisms organized in a matrix of extracellular polymeric material. Biofilms consist of microbial cells that attach to both surfaces and each other, whether they are living or non-living. These microbial biofilms can lead to hospital-acquired infections and are generally detrimental. They possess the ability to resist the human immune system and antibiotics. The National Institute of Health (NIH) states that biofilm formation is associated with 65% of all microbial illnesses and 80% of chronic illnesses. Additionally, non-device-related microbial biofilm infections include conditions like cystic fibrosis, otitis media, infective endocarditis, and chronic inflammatory disorders. This review aims to provide an overview of research on chronic infections caused by microbial biofilms, methods used for biofilm detection, recent approaches to combat biofilms, and future perspectives, including the development of innovative antimicrobial strategies such as antimicrobial peptides, bacteriophages, and agents that disrupt biofilms.

Antitumor effect of algae silver nanoparticles on human triple negative breast cancer cells

In recent years, metallic nanoparticles have gained increasing attention due to their prospective applications in the field of nanomedicine, with increasing research into their use in cancer therapy. In this current research, we investigated the effect of green synthesized Silver Nanoparticles (AgNPs) capped with Noctiluca scintillans algae extract. The phytochemicals present in the shell of AgNPs were identified using GC-MS. Different compounds with anticancer activity such as n-hexadecanoic acid, beta-sitosterol, stigmasterol and palmitic acid were detected among others. The effects of Algae-AgNPs synthesized were tested on MDA-MB-231 human breast cancer cells and HaCat human keratinocyte normal cells. Cell viability assay revealed a time and dose-dependent effect against breast cancer cells with a less potent effect against normal cells. The cell viability reduction is not attributed to a cytotoxic nor an antiproliferative effect of the Algae-AgNPs as attested by LDH release and BrdU incorporation. Algae-AgNPs exhibited an exceptional ability to specifically induce apoptosis in cancer cells and not normal cells. The observed effects are not attributed to the AgNPs, as demonstrated by the lack of impact of the Starch-AgNPs (used as a negative control) on cell survival and apoptosis. In addition to that, we show that Algae-AgNPs significantly reduced tumor cell migration by downregulation of matrix metalloprotease-9 levels. In vivo, the breast cancer xenograft model showed a significant reduction of tumor growth in mice treated with Algae-AgNPs. These findings highlight the promising potential of the green synthesized AgNPs as a safe targeted therapy for cancer treatment.

Design and Synthesis of 1,3-Diynes as Potent Antifungal Agents against Aspergillus fumigatus

Eugenol and isoeugenol, secondary metabolites isolated from the plant Myristica fragrans have displayed antifungal activities against Aspergillus fumigatus (IC₅₀ 1900 μM). Compounds having conjugated unsaturation have been of great use as antifungals i. e. amphotericin B, nystatin and terbinafine etc. Hence, in the present study, we have designed and synthesised 1,3-diynes by utilizing Glaser-Hay and Cadiot-Chodkiewicz coupling reactions to furnish possible antifungal agents. Synthesis of 1,6-diphenoxyhexa-2,4-diyne derivatives was achieved by Cu(I) catalysed coupling of propargylated eugenol, isoeugenol, guaiacol, vanillin and dihydrogenated eugenol or eugenol in good to excellent yields. All the synthesized compounds were evaluated against pathogenic fungus A. fumigatus. Among all the synthesized compounds, one of the compounds was found to be exhibiting promising antifungal activity with IC₅₀ value of 7.75 μM thereby suggesting that this type of scaffold could pave the way for developing new antifungal agents. The most active compound was found to be low cytotoxic when assayed against L-132 cancer cell line. Effect of the most active compound on ergosterol biosynthesis has also been studied. Also, the most active compound exhibited significant anti-biofilm activity although the concentration was found to be higher than its anti-fungal activity. Morphological changes in the biofilm were remarkable under confocal laser scanning microscopy.

Rutaretin1'-(6″-sinapoylglucoside): promising inhibitor of COVID 19 mpro catalytic dyad from the leaves of Pittosporum dasycaulon miq (Pittosporaceae)

SARS CoV2 is a novel strain of coronavirus, first reported in Wuhan of China, in 2019 and drugs specific to COVID-19 treatment are still lacking. The main protease (3CL) present in the new coronavirus strain is considered a potential drug target due to its role in viral replications. The plant Pittosporum dasycaulon Miq. is a medicinal plant reported to have prominent antimicrobial including antibacterial and antifungal activity. In this study, 12 natural compounds were selected on the basis of major peaks observed in the LC-HRMS analysis of P. dasycaulon aqueous leaves extract (AQLE). The pharmacological properties of the selected compounds against 3CLpro were investigated through in silico studies along with the standard antiviral drugs Lopinavir and Nelfinavir. The molecular docking study was done using Autodock 4.2 tool and visualized using Pymol (1.7.4.5 Edu). The docking analysis revealed that three compounds showed a better binding affinity than the standard drug Lopinavir. To validate the docking interactions, behaviour and stability of protein- ligand complex, molecular dynamics (100 ns) simulations were performed with the four best-ranked bioactive compounds identified through molecular docking analysis namely; Leptinidine, Rutaretin1'-(6″-sinapoylglucoside), Kalambroside A, and 5,7-dimethoxy', 4'methylenedioxyflavanone. The stability of the docking conformation was studied in depth by calculating the binding free energy using MM-PBSA method. Our findings on molecular docking, MD simulations and binding energy calculations suggest that Rutaretin1'-(6''-sinapoylglucoside) could be a potential inhibitor of COVID-19 3CLpro. However, considering the current pandemic situation of COVID-19, further research is required to experimentally validate their potential medicinal use against COVID-19 3CLpro both in vitro and in vivo along with clinical practices. Communicated by Ramaswamy H. Sarma.

Comprehensive profiling of aroma imparting biomolecules in foliar extract of Hibiscus fragrans Roxburgh: a metabologenesis perspective

Plants possess numerous secondary metabolites imparting flavor and aroma. However, fragrance inducing natural biomolecules and their potential sources are yet to be thoroughly explored. GC-MS analysis of a sweetly scented Malvacean liana; Hibiscus fragrans Roxburgh was conducted to explore and characterize the concerned aroma fingerprints with sound insights on anticipated array of biosynthetic pathways. Leaf extract of the plant was analyzed by Gas Chromatography-Mass Spectrometry (GC-MS) technique. Biosynthetic pathways of signature aroma compounds were deduced utilizing bioinformatic databases and reviewing literatures. A rare fragrant biomolecule '2-n-Heptylcyclopentanone' and 22 other aroma impacting biomolecules were detected and functional attributes were deliberately scrutinized. Interactive biosynthetic pathway schemes for all the 23 aromatic metabolomes including proposal for probable origin of 2-n-Heptylcyclopentanone and six other biomolecules (Pentadecanal; Cis-9-Hexadecenal; 14-Heptadecenal; Octadecanal; Undecane and 1-Decyne) with no previous biosynthesis report; out of a total of 47 GC-MS revealed metabolites were designed. Increased production of fragrant molecules in controlled surroundings availing biotechnological administration through metabolic bioengineering and in vitro tissue culture techniques may offer exciting dimensions to fragrance research.Communicated by Ramaswamy H. Sarma.

Isoeugenol affects expression pattern of conidial hydrophobin gene RodA and transcriptional regulators MedA and SomA responsible for adherence and biofilm formation in Aspergillus fumigatus

Aspergillus fumigatus is one of the major pathogenic fungal species, causing life-threatening infections. Due to a limited spectrum of available antifungals, exploration of new drug targets as well as potential antifungal molecules has become pertinent. Rodlet layer plays an important role in adherence of fungal conidia to hydrophobic cell surfaces in host, which also leads to A. fumigatus biofilm formation, contributing factor to fungal pathogenicity. From decades, natural sources have been known for the development of new active molecules. The present study investigates effect of isoeugenol on genes responsible for hydrophobins (RodA), adhesion as well as biofilm formation (MedA and SomA) of A. fumigatus. Minimum inhibitory concentrations (MIC and IC₅₀) of isoeugenol against A. fumigatus were determined using broth microdilution assay. The IC₅₀ results showed reduced hydrophobicity and biofilm formation as well as eradication after treatment with the compound and electron micrograph data corroborated these findings. The qRT-PCR showed a significant downregulation of genes RodA, MedA, SomA and pksP involved in hydrophobicity and biofilm formation. SwissADME studies potentiated drug-like propensity for isoeugenol which formed four hydrogen bonds with low binding energy (− 4.54 kcal/mol) at the catalytic site of RodA protein studied via AutoDock4. Hence, the findings conclude that isoeugenol inhibits conidial hydrophobicity and biofilm formation of A. fumigatus and further investigations are warranted in this direction.

In-silico screening of plant-derived antivirals against main protease, 3CLpro and endoribonuclease, NSP15 proteins of SARS-CoV-2

Novel Coronavirus or SARS-CoV-2 outbreak has developed a pandemic condition all over the world. The virus is highly infectious and spreads by human to human local transmission mode. Till date, there is no vaccination or drugs been approved for the treatment by the World Health Organisation. Henceforth, the discovery of the potential drugs is an urgent and utmost requirement for the medical fraternity. Since, the side effects of plant-derived compounds will be lower compared to synthetic/chemical drugs. The Main protease (3CL^pro or NSP5) and endoribonuclease (NSP15) proteins are necessity for viral replication and its survival in the host cell. In the present study, in-silico approach of drug development was used to search for potential antiviral plant-derived compounds as inhibitors against SARS-CoV-2 replication proteins. Eight plant-derived compounds of which the antiviral activity was known and available, and two reported drugs against SARS-CoV-2 selected for the molecular docking analysis. The docking results suggested that bisdemethoxycurcumin, demethoxycurcumin, scutellarin, quercetin and myricetin showed least binding energy, i.e., greater than −6.5 Kcal/mol against 3CL^pro and endoribonuclease of SARS-CoV-2. Further studies of ADME-Tox and bioavailability of drugs were also performed that exhibited efficient parameters of drug likeness. Molecular dynamics simulation calculations were performed for the most negative binding affinity of the compound to evaluate the dynamic behavior,and stability of protein-ligand complex. Our findings suggest that these compounds could be potential inhibitors of SARS‐CoV-2 main protease and endoribonuclease. However, further in-vitro and pre-clinical experiments would validate the potential inhibitors of SARS‐CoV‐2 proteins.

cis-9-Hexadecenal, a Natural Compound Targeting Cell Wall Organization, Critical Growth Factor, and Virulence of Aspergillus fumigatus

Aspergillus fumigatus causes several nosocomial pulmonary infections and accounts for high morbidity and mortality rate globally. Among various virulence factors, 1,8-dihydroxynaphthalene-melanin plays an important role in the survival during unfavorable conditions both in vivo and in vitro, masks various molecular patterns associated with A. fumigatus, and protects it from the host immune system. In the present study, we aim to understand the potential of cis-9-hexadecenal as an antimelanogenic compound and its role in modulating other associated virulence factors in A. fumigatus. cis-9-Hexadecenal is a bioactive compound that belongs to C₁₆ mono-unsaturated fatty-aldehyde groups. Minimum effective concentration of cis-9-hexadecenal affecting A. fumigatus melanin biosynthesis was determined using broth microdilution method. The spectrophotometric analysis revealed reduced melanin content (91%) and hydrophobicity (59%) at 0.293 mM of cis-9-hexadecenal. Cell surface organizational changes using electron microscopy showed altered demelanized smooth A. fumigatus conidial surface without any protrusions after cis-9-hexadecenal treatment. The transcript analysis of polyketide synthase (PKS) pksP/alb1 gene was quantified through qRT-PCR which revealed an upregulated expression. Total proteome profiling conducted through LC-MS-MS showed upregulated PKS enzyme but other downstream proteins involved in the 1,8-dihydroxynaphthalene-melanin biosynthesis pathway were absent. The homology modeling of PKS using Expasy's web server predicted that PKS is stable at varied conditions and is hydrophilic in nature. The Ramachandran plot by PROCHECK confirmed the 3-D structure of PKS to be reliable. Docking analysis using AutoDock-4.2.6 predicted the binding of cis-9-hexadecenal and PKS at Thr-264 and Ser-171 residue via hydrogen bonding at a low binding energy of -4.95 kcal/mol.