Anthocyanin and Isoflavone Contents in Korean Black Soybean Landraces and Their Antioxidant Activities

Anthocyanin and isoflavone contents and antioxidant activities of 56 Korean black soybean landraces were examined in this study. Total isoflavone content of 56 Korean black soybean landraces ranged from 43.8 to 347.5 mg/100 g. Total anthocyanin content ranged from 19.8 to 1,420.4 mg/100 g, with cyaniding-3-glucoside being the most abundant anthocyanin in all landraces, ranging from 12.2 to 1,207.3 mg/100 g. Antioxidant activities based on 2,2-diphenyl-1-picrylhydrazyl, 2,2 -azino-bis(3- ethylbenzothiazoline-6-sulphonic acid), ferric-reducing antioxidant power, and total polyphenol content assays showed wide variations, ranging from 17.1 to 76.6 (IC50), 53.5 to 127.7 (IC50), 5.4 to 34.2 mg ascorbic acid/g, and 9.7 to 36.8 mg gallic acid equivalents/g), respectively. Using relative antioxidant capacity index, IT156132 sample had the highest antioxidant activity. In clustering analysis, the 56 Korean black soybean landraces were classified into five groups. Group I consisted of four landraces with high isoflavone contents and antioxidant activities.