Abstract:

Objective: To investigate the chemical constituents of the antioxidant species present in black soybean. Methods:
The antioxidant species were isolated and purified from black soybean via silica gel, polyamide, D-101 macroperous
resin and Sephadex LH-20 column chromatography and their antioxidant activity was determined by the 1,1-diphenyl-2-
picrylhydrazyl radical (DPPH) scavenging method. Their chemical structures were identified on the basis of spectral analysis
and physicochemical properties. Results: Ten compounds including seven flavonoids were isolated and identified as genistein
(1), daidzein (2), glycitin (3), daidzin (4), genistin (5), quercetin-3-O-β-D-glucopyranoside (6), 3’-O-methylepicatechin-
7-O-β-D-glucopyranoside (7), daucosterol (8), maltol (9), and bergenin (10). Conclusion: Compounds 6, 7, 9 and 10 were
isolated from Glycine max (L.) Merr. for the first time, and the antioxidant activity of black soybean is mainly attributed to
the phenolic compounds.

Key words: Glycine max (L.) Merr., black soybean, chemical constituents, flavonoids, antioxidant activity