Bioprospecting endophytic fungi of forest plants for bioactive metabolites with anticancer potentials

Cancer continues to be a major cause of mortality worldwide, emphasizing the critical need for innovative and more effective anticancer drugs with enhanced efficacy and minimal side effects. In response, researchers have begun investigating the largely unexplored metabolites produced by fungal endophytes for the development of novel therapeutics. In this regard, the present work aims to assess the anticancer potential of the fungal endophytes of forest plants (local forest in Wrocław, Poland), which remains yet unexamined. Fungal endophytes were isolated from their host plants, purified, grown and their extracts were separately prepared from cell-free culture media and biomass. The prepared extracts were tested for their cytotoxic potentials against human melanoma, breast adenocarcinoma, lung carcinoma, and normal cell lines using the MTT-based assay. Cultures of these isolates were exposed to several doses of ⁶⁰Co gamma rays to study their effects on the cytotoxic potential of their cell-based and extracellular extracts against the beforementioned cell lines. Preparative thin-layer chromatography fractionation followed by GC-MS were applied to identify compounds in the active fractions. Five fungi, namely Penicillium yarmokense JAR-L1 (leaves of Sorbus aucuparia), Penicillium sp. sp. BRZ-B (bark of Betula pendula), Fusarium avenaceum KLON-B (bark of Acer platanoides), Penicillium charlesii SOS-B1 (bark of Pinus sylvestris), and Umbelopsis isabellina COR-L2 (leaves of Corylus avellana) showed high toxicity with increased specificity for cancer cells rather than healthy cells. Exposure to gamma rays at specific doses enhanced the cytotoxic potentials of extracts of these fungi. Bioactive compounds in the active bands after prep-TLC were identified. Some of the identified compounds from active fractions such as squalene, fenchone, α-phellandrene, p-Cymene, α-thujone, and 18-norabietane are being reported for the first time from fungal cultures. The findings of this study indicate that endophytic fungi may represent a promising and untapped reservoir of bioactive compounds with cytotoxic effects which opens new avenues for scientific exploration and could contribute to the advancement of novel anticancer therapeutics.