Abstract: Objective: To clarify the flavonoids and their antioxidant activities from the flowers of Mucuna sempervirens. Methods: High-speed countercurrent chromatography (HSCCC) and preparative HPLC were used to separate and purify the flavonoids. Their structural characterization was performed based on their physicochemical properties and spectral analysis. The antioxidant activities were evaluated by DPPH radical scavenging assay. Results: Eight compounds were isolated from the flowers of M. sempervirens, and identified as cyanidin3-O-6＇＇-O-α-rhamnopyranosyl-β-D-glucopyranoside (I), cyanidin3-O-β-D-glucopyranoside (II), quercetin-3-O-β-D-glucopyranoside (III), dihydroquercetin (IV), kaempferol (V), 6-C-β-L-arabinopyranosyl-8-C-β-D-glucopyranosyl apigeni (VI), kaempferol-3-O-α-L-rhamnopyranosyl-(1-6)-β-D-galactopyranoside (VII), and kaempferol-3-O-α-L-rhamnopyranosyl-(1-4)-β-D-glucopyranoside (VIII), respectively. The flavonoids I through V were the major antioxidant components with a dose-effect relationship. The flavonoids VI through VIII revealed lower antioxidant capacity. Conclusion: This study provides an insight into the flavonoid composition and their antioxidant activities in the flowers of Mucuna sempervirens.

Key words: Mucuna sempervirens, flavonoids, isolation, antioxidant activity