Isolation and characterization of a novel flavonoid possessing a 4,2-glycosidic linkage from green mature acerola (Malpighia emarginata DC.) fruit

The novel flavonoid, leucocyanidin-3-O-beta-D-glucoside, possessing a 4,2 ''-glycosidic linkage was isolated from green mature acerola (Malpighia emarginata DC.) puree and given the trivial name aceronidin. To examine the functions of aceronidin, its antioxidative activity and both its a-glucosidase and a-amylase inhibition activities, as a potential inhibitor of the sugar catabolic enzyme, were evaluated against those of taxifolin, catechin, isoquercitrin and quercitrin which each have a similar structure. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical quenching activity of aceronidin was stronger than that of a-tocopherol and comparable to that of Havonoids. In the yeast a-glucosidase inhibitory assay, aceronidin showed significantly greater inhibition than the other flavonoids tested. In the human salivary et-amylase inhibitory assay, aceronidin showed inhibition activity. Taken together, these results indicate aceronidin to be a potent antioxidant that may be valuable as an inhibitor of sugar catabolic enzymes.