Antioxidant and Cytotoxic Activity of the Wild Edible Mushroom Gomphus clavatus

The fruiting bodies of the edible mushroom Gomphus clavatus (Family Gomphaceae) were collected from the wild and extracted with solvents of increasing polarity. Crude extracts were evaluated for their total phenolic content, their antioxidant capacity, and their cytotoxic activity against MCF-7 and PC-3 cancer cell lines. Concerning total phenolics and antioxidant activity, the methanol extract showed the most potent radical scavenging activity with inhibition of 45.5% of 1,1-diphenyl-2-picrylhydrazyl at 3 mg/mL. Further chemical investigation of the methanol extract led to the isolation and identification of nine compounds, among them four ergosterol derivatives. Concerning cytotoxicity, the dichloromethane (DCM) extract showed the most interesting activity, with half-maximal inhibitory concentration (IC50) values of 55.3 and 49.0 mu g/mL in the MCF-7 and PC-3 cell lines, respectively. Further investigation of the DCM extract lead to the identification of methyl esters of fatty acids and the isolation of four fatty acids and three ergosterol derivatives. Ergosterol peroxide (compound 6) was one of the most active constituents, with IC50 values of 35.8 mu M and 30.6 mu M for MCF-7 and PC-3 cells, respectively, suggesting that the cytotoxic activity of the crude extract could be at least partly attributed to the presence of ergostan derivatives. Those findings suggest that G. clavatus can be considered as a medicinal food with antioxidant and chemopreventive activities.