Cytotoxicity and Cell Death Induction on a Cervical Cancer Cell Line by Crude Extracellular Product of Omphalotus nidiformis (Agaricomycetes) Mycelium.

Fungi have proved to be useful sources of compounds with antineoplastic properties. Although several metabolites isolated from species of the genus Omphalotus have shown cytotoxic effects on tumor cell lines. Few works have studied Omphalotus nidiformis. The activity of a whole crude extracellular product of a O. nidiformis micelyum strain is reported herein; this crude extract was able to reduce viability of cervical cancer HeLa cells (78% to 29%) after 24 h of exposure. Upon fractionation with dichloromethane, the fraction F1 was also capable of inhibiting cell viability, but the fraction F2 showed no effect. Both the crude extracellular product and F1 induced time- and concentration-dependent cell death by apoptosis through activation of caspase-3/7; in addition, both products induced a 3.5- to 5-fold increase in autophagy. The major components identified in both extracts by gas chromatography/mass spectrometry were 9-octadecenamide, tetradecanamide, hexadecanamide, and squalene, which could be responsible for the cytotoxic effect. Fungal metabolites with cytotoxic activity could be used in the future in combination with antineoplastic drugs for cancer treatment.