Antimicrobial secondary metabolites obtained from endophytic fungi inhabiting healthy leaf tissues of Houttuynia cordata Thunb., an ethnomedicinal plant of Northeast India

Abstract

Endophytic fungi from healthy leaf tissues of Houttuynia cordata Thunb., a widely used ethnomedicinal plant of Northeast India, were investigated, and an attempt has been made to characterize the antimicrobial metabolites from some potent endophytic strains. Altogether, 56 endophytic fungal isolates were obtained from surface-sterilized leaf fragments of H. cordata. The endophytes consisted of fungi belonging to genera Colletotrichum, Curvularia, Bipolaris, Corynespora, and Pseudozyma and non-sporulating fungi categorized as mycelia sterilia. Assay for antimicrobial activity revealed that 73.07% of the isolates showed activity against the test pathogens in varying degrees, whereas 92.32% of the isolates showed anticandida activity against Candida albicans. Among the isolates, two endophytic fungi identified as Colletotrichum coccodes and Phyllosticta capitalensis showed a significant antimicrobial activity against all the test pathogens. The metabolites obtained from C. coccodes revealed the presence of different functional groups and bioactive compounds such as geranylgeraniol, farnesol, hexacosanol, oleic acid, and squalene. Metabolites obtained from P. capitalensis also showed various functional groups and the presence of bioactive compound, 1-Octacosanol among several others. The study indicated that the ethnomedicinal plants are colonized by the rich diversity of endophytic fungi with antimicrobial activity. A further detailed investigation could practically lead to the development of pharmaceutical agents in the future.