Effect of sugar acylation on the antioxidant properties of Vitis vinifera red grape malvidin‐3‐glucoside

Summary This work aims at studying the influence of sugar acylation on the antioxidant properties of Vitis vinifera red grape malvidin‐3‐glucoside. The antioxidant properties of malvidin‐3‐glucoside, malvidin‐3‐acetylglucoside, malvidin‐3‐coumaroylglucoside and malvidin‐3‐caffeoylglucoside were measured using different techniques. Their antiradical and reducing properties were determined using the DPPH and FRAP method, respectively. Malvidin‐3‐caffeoylglucoside displayed a DPPH value (20.2 μ m Trolox eq.) much higher than malvidin‐3‐glucoside (13.6 μ m Trolox eq.), but no significant differences were observed from the FRAP assay. Furthermore, the ability of these compounds to inhibit lipid peroxidation in a liposome membrane system was examined by monitoring oxygen consumption and the formation of conjugated dienes. Both assays allowed concluding that malvidin‐3‐caffeoylglucoside and malvidin‐3‐coumaroylglucoside inhibit lipid peroxidation significantly more than malvidin‐3‐glucoside. Altogether, the results reported herein indicate that acylation of malvidin‐3‐glucoside with phenolic acids like caffeic or coumaric acids, but not acetic acid, increases their overall antioxidant properties.