Secondary metabolites of endophytic fungi from malaysian local herbs as potential antimicrobial and anticancer agents

Screening secondary metabolite compounds from endophytic fungi is a promising approach to meet the increasing threat of drug-resistant strains affecting humans. This study aims to explore the potential of endophytic fungi for antimicrobial and anticancer activity. Thirty endophytic fungal isolates were collected from the leaves of 13 local herbs. The majority of the isolates were identified using morphological characteristics and phylogenetic analyses of ITS rDNA sequences. Quantitative screening using disc diffusion assay showed that most of the fungal extracts inhibited both Gram-positive and Gram-negative bacteria with different degrees of inhibition zone ranging from 6.5 to 25.0 mm with no inhibition to Pseudomonas aeruginosa. All crude organic extracts of endophytic fungi in this study demonstrated promising bioactivities against reference strains of Bacillus cereus (ATCC 11778) and Salmonella typhimurium (ATCC 14028) with inhibition zones ranging from 17.0 to 24.6mm, respectively. The ethyl acetate extract showed MIC values between 62.50-125.00 μg/mL and MBC values ranging from 62.50-500.00 μg/mL against Gram-positive bacteria. Conversely, For Gram-negative bacteria.MIC values were between 125.00–250.00 μg/mL, and MBC values ranged from 250.0-1000.00 μg/mL. Extracts of fungal isolates were examined for cytotoxicity against four cancer cells with the result showing that isolates of Nigrospora sphaerica, Phyllosticta sp., and Diaporthe phaseolorum exhibited excellent antiproliferative effects against all types of cancer cell lines with IC50 values ranging between 1.946 – 16.96 µg/ml.  This study reveals that endophytic fungi could be a novel source for the isolating antimicrobials and anticancer agents.