Abstract:

Objective To study antioxidant activity of the crude extract and the active ingredient (pentagalloylglucose, PGG) extracted from Radix Paeoniae Alba.Methods The extracts obtained from Radix Paeoniae Alba by ultrasonic extraction with 50% of ethanol as extracting solvent. High-speed counter-current chromatography (HSCCC) was used for separation and purification of PGG in the crude extract from Radix Paeoniae Alba. PGG was analyzed and identified by HPLC and ESI-MS methods. The antioxidant activity of the crude extract and PGG were evaluated by1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and ferric reducing-antioxidant power(FRAP) assay and vitamin C (Vc) was used as a positive control. Results The purity of PGG was 95.7%, which was separated and purified in the crude extract from Radix Paeoniae Alba. DPPH assay showed that both of crude extract and PGG have strong scavenging effect on DPPH. The residual rates of the IC₅₀ were PGGcrude extract>Vc. FRAP assay showed that the PGG was the strongest antioxidant in comparison with the crude extract and Vc especially at lower concentrations (eg, 10 μg/mL). As the concentration increased, the FRAP values of each sample increased, and antioxidant abilities of samples also increased simultaneously. However, FRAP values of Vc increased more significantly. At the concentration of 100 μg/mL, FRAP value of Vc was 420.8 μmol/L that was very close to the FRAP value of crude extract at the same concentration, but still below FRAP value of PGG of 567.1 μmol/L.Conclusion It was shown that PGG, an ingredient extracted from Chinese medicine Radix Paeoniae Alba, has antioxidant activity. The antioxidant effect of PGG was much higher than that of the positive control Vc. PGG may become an effective anti-oxidant with a wide application for clinical treatment of diseases.

Key words: Radix Paeoniae Alba, pentagalloylglucose, anti-oxidation, 1,1-diphenyl-2-picrylhydrazyl assay, ferric reducing-antioxidant powerassay