Cytotoxicity, antioxidant, antimicrobial studies and phytochemical screening of endophytic fungi isolated from Justicia gendarussa

Endophytic fungi are a group of fungi that reside in the living plant without causing any disease symptoms. It shows symbiotic/mutualistic characteristics with host plants. Endophytic fungi may increase the host defense system against various pathogenic microorganisms and may encompass secondary metabolites of respective host plants. Isolation of endophytic fungi and its metabolites from Justicia gendarussa plant grown in Bangladesh is a recent and new approach. A total of seven endophytic fungi were isolated and purified from the leaf and bark part of the plant. All of the isolated endophytic fungi were identified up to genus level on the basis of macroscopic and microscopic characteristics and up to species level on the basis of molecular characteristics as Colletotrichum gloeosporioides, Diaporthe pseudomangiferae, Pseudopestalotiopsis camelliae-sinensis, Colletotrichum gloeosporioides, Fusarium solani, Colletotrichum tropicale and Colletotrichum siamense. 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. Fungal strain Pseudopestalotiopsis camelliae-sinensis exhibited significant antiradical activity through DPPH scavenging method and moderate antimicrobial activity against a wide range of human pathogenic microbes. Using brine shrimp lethality bioassay, all the isolates showed strong cytotoxic activity, therefore suggested that all the extracts may have bioactive metabolites. Overall, these findings indicate that Justicia gendarussa and its associated endophytic fungi could be an important source for exploring potentially bioactive compounds or leads for the new drug candidates.