Antioxidant activities of extracts and flavonoid compounds from Oxytropis falcate Bunge

Abstract

The antioxidant properties of the various extracts and flavonoids prepared from Oxytropis falcate Bunge were investigated by 1,1-diphenyl-2-picryldydrazyl (DPPH) radical-scavenging assay. In the chloroform, ethyl acetate and n-butanol extracts, the ethyl acetate extract exhibited the highest antioxidant activity (IC₅₀ = 2.05 mg mL⁻¹). Furthermore, rhamnocitrin, kaempferol, rhamnetin, 2′,4′-dihydroxychalcone and 2′,4′, β-trihydroxy-dihydrochalcone were purified from chloroform and ethyl acetate extracts. The radical-scavenging activities of the five compounds were also measured and the results showed that kaempferol (IC₅₀ = 0.11 mg mL⁻¹), rhamnetin (IC₅₀ = 0.14 mg mL⁻¹) and rhamnocitrin (IC₅₀ = 0.15 mg mL⁻¹) exhibited considerable antioxidant activities, but the antioxidant activities of the two dihydrochalcones were very weak. Although these flavonoids are known, this is the first report of antioxidant activity in this plant.

Keywords:

• Oxytropis falcate
• extracts
• flavonoids
• antioxidant activity
• DPPH

Acknowledgements

This work was supported by the Research Fund of the Chinese Academy of Sciences, P.R. of China “The study on the standard of characteristic national drugs in western China”. Project number KGCX2-SW-213-08.