Eicosane: An antifungal compound derived from Streptomyces sp. KF15 exhibits inhibitory potential against major phytopathogenic fungi of crops.

In the present scenario, food security is of major concern due to exponentially increasing population and depleted crop production. The fungal diseases have contributed majorly to the scarcity of staple food products and economic loss worldwide. This problem could be tackled by preventing the crop loss during both pre and post-harvest seasons. During the current investigation, the bioactive compound eicosane was extracted from Streptomyces sp. KF15, subjected to purification and identified based on mass spectrometry and NMR analysis. The evaluation of in-vitro antifungal activity was done by poisoned food method, SEM analysis and growth pattern analysis. The bioactive compound eicosane with molecular weight of 282.5475 g/mol was purified by column chromatography and the straight chain hydrocarbon structure of CH3CH2(18)CH3 was elucidated by NMR analysis. In poisoned food assay, eicosane effectively inhibited the radial growth of all tested fungal pathogens; F. oxysporum was found to be the most sensitive with 24.2%, 33.3%, 42.4%, and 63.6% inhibition at 25-100 µg/ml concentrations. The SEM micrograph established clear differences in the morphology of eicosane treated fungi with damaged hyphae, flaccid mycelium and collapsed spores as compared to the tubular, turgid and entire fungi in control sample. Finally, the growth curve assay depicted the right side shift in the pattern of eicosane treated fungi indicating the delay in adapting to the conditions of growth and multiplication. The findings of this study encourage further research and development towards the novel antifungal drugs that can act against major phytopathogens.

Efficacy of Penicillium limosum Strain AK-7 Derived Bioactive Metabolites on Antimicrobial, Antioxidant, and Anticancer Activity against Human Ovarian Teratocarcinoma (PA-1) Cell Line.

Natural metabolites from beneficial fungi were recognized for their potential to inhibit multidrug-resistant human and plant fungal pathogens. The present study describes the isolation, metabolite profiling, antibacterial, and antifungal, antioxidant, and anticancer activities of soil fungi. Among the 17 isolates, the AK-7 isolate was selected based on the primary screening. Further, the identification of isolate AK-7 was performed by 18S rRNA sequencing and identified as Penicillium limosum (with 99.90% similarity). Additionally, the ethyl acetate extract of the Penicillium limosum strain AK-7 (AK-7 extract) was characterized by Fourier Transform Infrared Spectroscopy (FTIR) and a Gas Chromatography-Mass Spectroscopy (GC-MS) analysis, and the results showed different functional groups and bioactive metabolites. Consequently, a secondary screening of antibacterial activity by the agar well diffusion method showed significant antibacterial activity against Gram-negative and Gram-positive bacterial pathogens. The AK-7 extract exhibited notable antifungal activity by a food poisoning method and showed maximum inhibition of 77.84 ± 1.62%, 56.42 ± 1.27%, and 37.96 ± 1.84% against Cercospora canescens, Fusarium sambucinum and Sclerotium rolfsii phytopathogens. Consequently, the AK-7 extract showed significant antioxidant activity against DPPH and ABTS•+ free radicals with IC50 values of 59.084 µg/mL and 73.36 µg/mL. Further, the anticancer activity of the AK-7 extract against the human ovarian teratocarcinoma (PA-1) cell line was tested by MTT and Annexin V flow cytometry. The results showed a dose-dependent reduction in cell viability and exhibited apoptosis with an IC50 value of 82.04 µg/mL. The study highlights the potential of the Penicillium limosum strain AK-7 as a source of active metabolites and natural antibacterial, antifungal, antioxidant, and anticancer agent, and it could be an excellent alternative for pharmaceutical and agricultural sectors.

Unveiling the Pharmacological Significance of Marine Streptomyces violaceusniger KS20: Isolation, Characterization, and Assessment of Its Biomedical Applications.

Marine actinomycetes represent a highly favorable source of bioactive compounds and have been the mainstay of much research in recent years. Recent reports have shown that marine Streptomyces sp. can produce compounds with diverse and potent biological activities. Therefore, the key objective of the study was to isolate and screen a potential actinomycete from marine ecosystems of Devbagh and Tilmati beaches, Karwar. Streptomyces sp. KS20 was characterized and the ethyl acetate extract (EtOAc-Ex) was screened for biomedical applications. Streptomyces sp. KS20 produced grayish-white aerial and pale-yellow substrate mycelia and revealed an ancestral relationship with Streptomyces violaceusniger. Optimum growth of the organism was recorded at 30 °C and pH 7.0. The metabolite profiling of EtOAc-Ex expressed the existence of several bioactive metabolites, whereas the functional groups were indicated by Fourier transform infrared (FTIR) spectroscopy. A considerable antioxidant activity was shown for EtOAc-Ex with IC50 of 92.56 µg/mL. In addition to this, Streptomyces sp. KS20 exhibited significant antimicrobial properties, particularly against Escherichia coli, where a zone of inhibition measuring 36 ± 0.83 mm and a minimum inhibitory concentration (MIC) of 3.12 µg/mL were observed. The EtOAc-Ex even revealed significant antimycobacterial potency with IC50 of 6.25 µg/mL. Finally, the antiproliferative potentiality of EtOAc-Ex against A549 and PC-3 cell lines revealed a constant decline in cell viability while raising the concentration of EtOAc-Ex from 12.5 to 200 µg/mL. The IC50 values were determined as 94.73 µg/mL and 121.12 µg/mL for A549 and PC-3 cell lines, respectively. Overall, the exploration of secondary metabolites from marine Streptomyces sp. KS20 represents an exciting area of further research with the potential to discover novel bioactive compounds that could be developed into therapeutics for various medical applications.

Antimicrobial Efficacy of 7-Hydroxyflavone Derived from Amycolatopsis sp. HSN-02 and Its Biocontrol Potential on Cercospora Leaf Spot Disease in Tomato Plants.

The actinomycete strain HSN-02 was isolated from the soil of a mining field in the Sandur region, Bellary, Karnataka, India. According to the morphological, cultural, physiological, and biochemical characteristics and the 16S rDNA sequence analysis, the strain HSN-02 was identified as Amycolatopsis sp. The antimicrobial activity strain HSN-02 presented stable and moderate inhibitory activity against human pathogens. In pot experiments in the greenhouse, the development of Cercospora leaf spot was markedly suppressed by treatment with the purified compound from the strain HSN-02, and the control efficacy was 45.04 ± 1.30% in Septoria lycopersici-infected tomato plants. A prominent compound was obtained from the fermentation broth of the strain HSN-02 using column chromatography and HPLC. The chemical structural analyses using UV, FTIR, HR-ESI-MS, and NMR confirmed that the compound produced by the strain HSN-02 is 7-hydroxyflavone. This investigation showed the role which the actinomycete strain can play in controlling leaf spots caused by S. lycopersici to reduce treatments with chemical fungicides.

Aspergillus niger CJ6 extract with antimicrobial potential promotes in-vitro cytotoxicity and induced apoptosis against MIA PaCa-2 cell line.

Nowadays, the increased number of multidrug-resistant strains among pathogens is a severe public health concern and cancer is posing a great threat for humans. These problems should be tackled with the development of novel and broad-spectrum antimicrobials from microbial origin. During the present study, the bioactive secondary metabolites from Aspergillus niger CJ6 were extracted, characterized; their biological properties were evaluated by subjecting them for antimicrobial, antifungal and anticancer activities. The potent isolate Aspergillus niger CJ6 with nucleotide sequence of 959 base pairs showed antagonistic activity against fungal pathogens in dual culture. The chemical profiling of crude ethyl acetate extract indicated the presence of various bioactive molecules belonging to phenolic, hydrocarbons, and phthalate derivative classes. In antimicrobial activity, the crude extract displayed increasing activity with increased concentration; the highest activity observed against Shigella flexneri with 15 ± 1.0, 19 ± 0.5, 20 ± 1.0 and 24 ± 1.0 mm zones of inhibition at 25, 50, 75 and 100 µl concentrations. The MTT assay illustrated deformed cells of MIA PaCa-2 cell line in in-vitro cytotoxic activity; outflow of cell matrix and membrane rupture; the IC50 of 90.78 µg/ml suggested moderate potential of extract to prevent cancer cell growth. The apoptosis/necrosis study by flow cytometer exhibited 8.98 ± 0.85% early and 73 ± 0.7% of late apoptotic population with 3.8 ± 1.1% necrotic cells; only 14.22 ± 0.6% of healthy cells suggested the increased apoptosis inducing capacity of Aspergillus niger CJ6 crude extract. The outcomes of this study persuade further exploration on the identification, purification and development of novel bioactive agents that could help battle fatal diseases in humans.

Biosynthesis and characterization of polysaccharide-capped silver nanoparticles from Acalypha indica L. and evaluation of their biological activities.

Biosynthesized silver nanoparticles (AgNPs) are gaining popularity due to their distinctive biological applications. In this research work, an eco-friendly method of synthesizing AgNPs from the leaf polysaccharide (PS) of Acalypha indica L. ( A. indica) was carried out. Synthesis of polysaccharide-AgNPs (PS-AgNPs) was indicated by visual detection of colour change from pale yellow to light brown. The PS-AgNPs were characterized with different techniques and further evaluated for biological activities. The Ultra violet-visible (UV-Vis.) spectroscopy expressed a sharp absorption peak at 415 nm confirmed the synthesis. Atomic force microscopy (AFM) analysis revealed the size range of particles from 14 nm to 85 nm. Fourier transform infrared (FTIR) analysis detected the presence of various functional groups. The cubic crystalline structure of PS-AgNPs was confirmed by X-ray diffraction (XRD) and the particles were found to be oval to polymorphic shaped through transmission electron microscopy (TEM) with sizes from 7.25 nm to 92.51 nm. Energy dispersive X-ray (EDX) determined the presence of silver in PS-AgNPs. The zeta potential was -28.0 mV, which confirmed the stability and an average particle size of 62.2 nm was calculated through dynamic light scattering (DLS). Lastly, the thermo gravimetric analysis (TGA) showed the PS-AgNPs were resistant to high temperature. The PS-AgNPs exhibited significant free radical scavenging activity with an IC50 value of 112.91 µg/ml. They were highly capable of inhibiting the growth of different bacterial and plant fungal pathogens and also active to reduce the cell viability of prostate cancer (PC-3) cell line. The IC50 value was 101.43 µg/ml. The flow cytometric apoptosis analysis revealed the percentage of viable, apoptotic and necrotic cells of PC-3 cell line. According to this evaluation, it can be concluded that these biosynthesized and environmentally friendly PS-AgNPs are helpful to improve therapeutics because of significant antibacterial, antifungal, antioxidant, and cytotoxic properties to open up new possibilities for euthenics.

Plumeria alba-Mediated Green Synthesis of Silver Nanoparticles Exhibits Antimicrobial Effect and Anti-Oncogenic Activity against Glioblastoma U118 MG Cancer Cell Line.

Plumeria alba (P. alba) is a small laticiferous tree with promising medicinal properties. Green synthesis of nanoparticles is eco-friendly, cost-effective, and non-hazardous compared to chemical and physical synthesis methods. Current research aiming to synthesize silver nanoparticles (AgNPs) from the leaf extract of P. alba (P- AgNPs) has described its physiochemical and pharmacological properties in recognition of its therapeutic potential as an anticancer and antimicrobial agent. These biogenic synthesized P-AgNPs were physiochemically characterized by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscope (TEM), atomic force microscopy (AFM), X-ray diffractometry (XRD), and zeta potential analysis. Antimicrobial activity was investigated against Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Enterococcus faecalis, Bacillus subtilis, Streptococcus pneumoniae, Candida albicans, and Candida glabrata. Anticancer activity against glioblastoma U118 MG cancer lines was investigated using an MTT assay, and apoptosis activity was determined by flow cytometry. UV-visible spectroscopic analysis portrayed surface plasmon resonance at 403 nm of synthesized P-AgNPs, and FTIR suggested the presence of amines, alkanes, and phenol molecules that could be involved in reduction and capping processes during AgNPs formation. Synthesized particles were spherical in shape and poly-dispersed with an average particle size of 26.43 nm and a poly-dispersity index (PDI) of 0.25 with a zeta potential value of -24.6 mV, ensuring their stability. The lattice plane values confirm the crystalline nature as identified by XRD. These P-AgNPs exhibited potential antimicrobial activity against selected human pathogenic microbes. Additionally, the in vitro MTT assay results showed its effective anticancer activity against the glioma U118 MG cancer cell line with an IC50 value of 9.77 µg/mL AgNPs by initiating apoptosis as identified by a staining study with flow cytometric Annexin V-Fluorescein Isothiocyanate (FITC) and Propidium Iodide (PI). Thus, P. alba AgNPs can be recommended for further pharmacological and other biological research. To conclude, the current investigation developed an eco-friendly AgNPs synthesis using P. alba leaf extract with potential cytotoxic and antibacterial capacity, which can therefore be recommended as a new strategy to treat different human diseases.

Bioprospection and secondary metabolites profiling of marine Streptomyces levis strain KS46.

The quest for novel broad spectrum bioactive compounds is needed continuously because of the rapid advent of pathogenic multi drug resistant organisms. Actinomycetes, isolated from unexplored habitats can be a solution of this problem. The motive of this research work was isolation of actinomycetes having potential antimicrobial activities from unexplored regions of Devbag and Tilmati beach. The isolated actinomycetes were screened against pathogenic microbes for antimicrobial activities through cross streak method. Enzyme production activity was checked for these actinomycetes for amylase, protease, cellulase and lipase enzymes. Further antimicrobial activity of ethyl acetate extract of the potent strain KS46 was performed. The strain KS46 was identified with 16S rRNA gene sequencing and secondary structure was analysed. Gas chromatography-Mass spectrometry (GC-MS) profiling was conducted to ascertain the presence of bioactive metabolites in the ethyl acetate extract. The collected samples were pre-treated and 70 actinomycetes were isolated. The Streptomyces sp. strain KS46 showed the best antimicrobial activity in primary screening. Ethyl acetate extract of the strain KS46 revealed antimicrobial activity against S. aureus, B. subtilis, B. cereus, E. faecalis, K. pneumoniae, E. coli, S. flexneri, C. albicans and C. glabrata. The 16S rRNA gene sequencing identified the strain KS46 as Streptomyces levis strain KS46. The GC-MS metabolite profiling of the ethyl acetate extract revealed the availability of 42 compounds including fatty acid esters, fatty acid anhydrides, alkanes, steroids, esters, alcohols, carboxylic ester, etc. having antibacterial, antifungal, antiproliferative, antioxidant activities. This study indicated that Devbag and Tilmati beaches being untapped habitats have enormous diversity of promising antimicrobial metabolite producing actinomycetes. Therefore, further exploration should be carried out to characterize the potential actinomycetes, which can be optimistic candidates for generation of novel antimicrobial drugs.