The methanolic extract of Monascus purpureus cultivated by solid-state fermentation on rice showed strong 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and better yield as compared to other polarity based extracted fractions. It was selected for further purification of the antioxidant. The activity-guided repeated fractionation of methanolic extract on a silica gel column chromatography yielded a compound that exhibited strong antioxidant activity. Based on the spectroscopic analysis by UV, IR, H-1 NMR, C-13 NMR, 2D-HSQCT NMR, and MS, the antioxidant isolated was elucidated as a derivative of dihydromonacolin-K, where the ester group is 2-methyl propionate, designated as dihydromonacolin-MV. The DPPH radical was significantly scavenged by the dihydromonacolin-MV (IC50 20 +/- 1 mu g ml(-1)). The dihydromonacolin-MV showed strong inhibition of lipid peroxidation in a liposome model with an IC50 value of 5.71 +/- 0.38 mu g ml(-1) and superoxide radical scavenging activity with an IC50 value of 163.97 +/- 2.68 mu g ml(-1).