Cytotoxic secondary metabolites from endophytic fungus <i>Xylaria</i> sp.: isolation and <i>in vitro/in silico</i> evaluation

This study aimed to isolate secondary metabolites produced by the endophytic fungus <i>Xylaria</i> sp. derived from <i>Andrographis paniculata</i> and to evaluate their cytotoxic potential using <i>in vitro</i> and <i>in silico</i> methods. The fungus was cultivated on rice medium for three weeks, extracted with ethyl acetate, and purified by chromatographic techniques, yielding two compounds identified as 19,20-epoxycytochalasin C (<b>1</b>) and ergosterol (<b>2</b>) based on NMR and FT-IR analyses. Both compounds exhibited cytotoxicity against MCF-7 breast cancer cells, with IC₅₀ values of 38.4 and 45.7 μM, respectively. Molecular docking against the HER2 protein supported the <i>in vitro</i> results, showing binding free energies of -8.023 and -7.310 kcal/mol for compounds <b>1</b> and <b>2</b>, respectively. These findings suggest that both metabolites possess significant anticancer potential, particularly as candidate anticancer compounds against MCF-7 cancer cells. Notably, this is the first report of the chemical characterisation of <i>Xylaria</i> sp. associated with <i>A. paniculata.</i>