Biosynthetic pathway of Monascus pigment production is very complex. The mutant, M. purpureus CFR410-11 has produced new monacolin and subsequently it was predicted to produce new pigment molecule as well. Accordingly a pigment molecule was isolated by employing silica gel column chromatography. The TLC and HPLC data revealed the purity of isolated pigment molecule. The interpretation of UV-vis, FTIR, NMR and HRMS spectra of the pigment lead to its identity as 10-Hydroxy-3-(Prop-1-en-1-yl)-5-undecanoyl-10,10a-1H-benzo(g) isochromene-8-carbaldehyde and designated as monashin. Apparently, the production of new derivative of pigment molecule is due to the changes in biosynthetic pathway caused by the mutation or reduction, oxidation of other molecules. The pigment monashin exhibited the DPPH (26%), H2O2 (77%), and reducing power (0.57 AU) activity at 37.5, 40 and 46.15 mu g ml(-1) concentration respectively. These antioxidant functions suggested the biological importance of monashin.