Abstract: Objective: To separate, purify and biologically characterize antioxidant peptides from Radix Puerariae. Methods: Widely grown Radix Puerariae was extracted with 30% ethanol aqueous solution, dialyzed, lyophilized, purified by DEAE anion exchange chromatography and reversed-phase HPLC to obtain an antioxidant peptide fraction with the highest reducing power, named as PE1. PE1 was tested by ninhydrin reaction and its molecular weight was measured. Moreover, the scavenging effects in vitro on superoxide anion (by pyrogallol autoxidation method), DPPH and hydroxyl radicals (by Fenton reaction method) were evaluated. Results: A single peak was observed in the reversed-phase HPLC pattern of PE1. The reaction between PE1 and ninhydrin was positive, and the molecular weight of PE1 was approximately 746 D. PE1 was effective in scavenging superoxide anion, DPPH and hydroxyl radicals. The scavenging rate was 80.01% at 0.652 mg/mL against hydroxyl radicals, 97.35% at 5 mg/mL against superoxide anion radicals and 75.02% at 3.5 mg/mL against DPPH radicals with an IC50 of 2.83 mg/mL. Conclusion: PE1 has strong radical scavenging activity.

Key words: Radix Puerariae, DEAE ion-exchange chromatography, antioxidant peptide, free radical