Cyathusals A, B, and C, antioxidants from the fermented mushroom Cyathus stercoreus

Three new polyketide-type antioxidative compounds, cyathusals A ( 1), B ( 2), and C ( 3), and the known pulvinatal ( 4) were obtained from the fermented mushroom Cyathus stercoreus. The structures of the compounds were characterized on the basis of NMR and mass spectroscopic data. Cyathusals A, B, and C and pulvinatal showed free radical scavenging activities on the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical with EC50 values of 41.6, 46.0, 26.6, and 28.6 mu M, respectively, and on the 2,2 '-azinobis(3-ethylbenzothiazoline-6-sulfonate) ( ABTS) cation radical with EC50 values of 7.9, 11.1, 9.1, and 8.4 mu M, respectively.