A unique highly oxygenated pyrano[4,3-c][2]benzopyran-1,6-dione derivative with antioxidant and cytotoxic activities from the fungus Phellinus igniarius.

[structure: see text] A unique pyrano[4,3-c][2]benzopyran-1,6-dione derivative with an unprecedented carbon skeleton, phelligridin G (1), has been isolated from the fruiting body of the fungus Phellinus igniarius. Its structure was elucidated by detailed spectroscopic analysis. A possible biogenetic origin of 1 mediated by the fungal metabolite precursor 4-hydroxy-6-methyl-2-pyrone was postulated. Phelligridin G (1) showed antioxidant activity inhibiting rat liver microsomal lipid peroxidation and moderate selective cytotoxic activities against human cancer cell lines.