Bioactive potential of secondary metabolites derived from medicinal plant endophytes

Abstract

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 Rf 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.