Phenolic compounds and antioxidant activity of adzuki bean cultivars

The phenolic compounds and radical scavenging activity of ethanolic extracts of five adzuki beans were evaluate according to cultivar. The predominant phenolic acids in five cultivars of adzuki bean were (+)-catechin and gallic acid. Antioxidant capacities were determined using 2,2-diphenyl-1-picrylhydrazyl and 2,2-azinobis (3-ethylbenothiazoline-6-sulphonic acid) diammonium salt, and reducing power was positively enhanced according to the total polyphenolic content. In a cell-based assay, adzuki beans showed cytoprotective effects against oxidative stress induced by tert-butyl hydroperoxide and inhibitory effects on the production of reactive oxygen species, except for the cultivar Vigna angularis var. nipponensis cv. Whinnarae. In conclusion, (+)-catechin was the predominant phenolic compound found in adzuki beans, but there were differences according to the cultivar. Overall, the adzuki bean cultivars showed different antioxidant activities and cytoprotective effects according to the concentration and composition of phenolic compounds.