Medicinal plants have been used as an alternative medicine to promote human health and longevity in many regions of the world since ancient times. In recent years, many novel secondary metabolites from higher fungi have been isolated and reported to provide lead compounds for new drug discovery like antimicrobial, antioxidant, and anticancer agents, etc. A total of 42 endophytic fungi were isolated from 11 different medicinal plants collected from Tamil Nadu, India. The capability of medicinal plant endophytic fungi for the production of bioactive secondary metabolites was evaluated under in vitro conditions. The most frequently isolated fungi were Alternaria sp. Fusarium sp. and mycelia sterilia. The bioactive secondary metabolites of these endophytes were obtained by liquid-liquid extraction with ethyl acetate. Among which 15 showed antimicrobial activity towards potential human pathogens such as Escherichia coli, Salmonella typhi, Proteus mirabilis, Staphylococcus aureus, and Corynebacterium diphtheriae with variable zone of inhibition. Maximum secondary metabolite production with good mycelial growth and antimicrobial activity was observed in Alternaria sp. MGTMMP031. Moreover, in-vitro antioxidant and anticancer activity were also evaluated. The crude secondary metabolite was characterized by ultraviolet spectrum (UV), infrared spectrum (FT-IR) and thin layer chromatography (TLC) with R f value of 0.35 and the bioactive secondary metabolite was identified as alternariol methyl ether. The results concluded that secondary metabolite from Alternaria sp. may represent a potential ingredient for pharmaceutical application and are worthy of future study.

In the present study lipopeptide biosurfactant with high emulsification capacity produced by human skin bacterium Paenibacillus thiaminolyticus was purified and subjected to FTIR and NMR spectral analysis which gave evidence of the active characteristics of the surfactant. To augment the antivirulent potential further, the mixer of copper and copper oxide nanoparticles (CuNPs) was synthesized, and characterized by UV–Visible spectroscopy, SEM-EDAX, TEM, and Zeta analysis. Here, we attempted to enhance the antimicrobial and antibiofilm activity with the assistance of encapsulated preparation of lipopeptide and CuNPs in multilamellar liposomes. The proposed mechanism of action of lipopeptide and CuNPs liposomal preparation negatively influences the cell metabolism, secreted virulence such as staphyloxanthin, pyocyanin, and extracellular polysaccharides. The significant decline in the growth of MRSA and P. aeruginosa in both planktonic form and biofilm by lipopeptide and CuNPs treatment were visualized using scanning electron microscopy and High content screening imaging system. In vivo studies revealed that treatment with lipopeptide and CuNPs in multilamellar liposomes extended the lifespan of infected Caenorhabditis elegans by about 75%. Therefore, this study typifies lipopeptide and CuNPs could credibly be a substantial substitute over conventional antibiotics in averting the biofilm associated pathogenesis of MRSA and P. aeruginosa.

Schematic representation of the biosurfactant production and evaluation of anti-pathogenic potential.

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