Abstract Two endophytic fungi (AIn-L4 and AIn-L5) were isolated from the leaves of Azadirachta indica. The fungi were subjected to solid state fermentation on rice medium and the fungal secondary metabolites were extracted using ethyl acetate. The fungal extracts were screened for possible antimicrobial and cytotoxic activities. Also, some of the bioactive compounds of the extracts were detected using high-performance liquid chromatography (HPLC) analysis. The result of the antimicrobial assay reveal that at 1 mg/mL, AIn-L5 extract showed mild antibacterial activity against B. subtilis and S. typhi with inhibition zone diameters of 4 and 5 mm respectively. Extract of AIn-L4 showed no activity against any of the test bacteria, and both fungal extracts showed no antifungal activity against the test fungi. Result of the cytotoxicity assay reveals that the extract of AIn-L4 showed 100% cytotoxic activity and completely inhibited the growth of mouse lymphoma cells L5178Y, while AIn-L5 showing no cytotoxic activity. The HPLC analysis of AIn-L4 extract revealed the presence of aureonitol, while AIn-L5 showed the presence of scytalone, cladosporin, and citreoisocoumarinol. The study showed that these endophytic fungi could be promising sources of novel bioactive compounds with pharmaceutical or industrial importance.
Keywords Azadirachta indica, endophytic fungi, secondary metabolites, antimicrobial and cytotoxic activities, HPLC analysis.