Radical scavenging activity and antioxidant properties of tannins fromGuiera senegalensis (Combretaceae)

The antioxidant properties of nine tannins isolated and characterized from different parts of Guiera senegalensis were evaluated. Interesting results showed that galloylquinic acids (hydrolysable tannins), resulting from a tri- or tetra-substitution of galloyl groups on the quinic acid skeleton, played a crucial role in the inhibitory effect on Fe2+-induced lipid peroxidation in rat liver microsomes and radical scavenger activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) test. The effects of all tannins were markedly higher than that of gallic acid. Condensed tannins such as epicatechin and epigallocatechin gallate also showed fairly significant effects in both tests. © 1998 John Wiley & Sons, Ltd.