Isolation and evaluation of the antioxidant activity of phenolic constituents of the Garcinia brasiliensis epicarp

Abstract

A new glycosylated biflavonone, morelloflavone-4 '''-O-beta-D-glycosyl, and the known compounds 1,3,6,7-tetrahydroxyxanthone, morelloflavone (fukugetin) and morelloflavone-7 ''-O-beta-D-glycosyl (fukugeside) were isolated from the epicarp of Garcinia brasiliensis collected in Brazil. The structures of these compounds were established using H-1 and C-13 NMR, COSY, gHMQC and gHMBC spectroscopy. The compounds exhibited antioxidant activity. The greatest potency was displayed by morelloflavone (2), with IC50 = 49.5 mM against DPPH and absorbance of 0.583 at 400 mu g/mL for the reduction of Fe3+. The weakest potency was displayed by 1,3,6,7-tetrahydroxyxanthone (1), with IC50 = 148 mM against DPPH and absorbance of 0.194 at 400 mu g/mL for the reduction of Fe3+. (C) 2011 Elsevier Ltd. All rights reserved.