Exploration of endophytic fungi and their bioactive potential associated with Punica Granatum

Abstract

Endophytic fungi are a group of fungi that reside in the living plant without causing any symptoms. It shows symbiotic/mutualistic characteristics with host plants. Endophytic fungi may increase the host defense system against various pathogenic microorganism and contains secondary metabolites of the respective host plant. Isolation of endophytic fungi and it’s metabolites from Punica Granatum plant grown in Bangladesh is a recent and new approach. A total of six endophytic fungi were isolated and purified from the leaf and bark part of the plant. All of the isolated endophytic fungi namely DgB1, DgB3, DgL3, and DgL4 were identified up to genus level based on macroscopic and microscopic characteristics and up to species level based on molecular characteristics as Diaporthe pseudomangiferae, Diaporthe pseudomangiferae, Phomopsis tersa, and Colletotrichum siamense respectively. Preliminary chemical screening of the fungal extracts by thin layer chromatographic technique revealed the presence of various compounds such as flavonoids, anthraquinones, couramins, isocoumarins etc. An antimicrobial study was carried out against a wide range of both Gram-positive and Gram-negative bacteria by disc diffusion method, and testing of the antioxidant property was done by following DPPH scavenging method. Fungal strain DgL4 showed significant antioxidant activity of 21.08 µg/ml and DgB1 showed moderate antimicrobial activity. The extract DgL3 was later purified by solvent treatment with mixtures of n-Hexane, DCM, and methanol. Structural elucidation of the isolated compound was done through their spectral data (NMR). Overall, these findings indicate that the medicinal plants of Bangladesh and their associated endophytic fungi could be an ideal target for the discovery of potentially bioactive compounds or lead structures for new drugs.