Antioxidative Effect of Pueraria Mirifica

Abstract

Pueraria mirifica (White Kwao Keur) is a thai rejuvenating folk medicine

which contains many phytoestrogens including miroestrol, deoxymiroestrol and

insoflavonoid group (kwakhurin, daidzein, genistein, etc.) which possess estrogenic

activity. This study aimed to investigate the antioxidative effect of Pueraria mirifica

in several models both in vitro and ex vivo. Free radical scavenging assay using ESR

method, the EC50 of superoxide- and hydroxyl scavenging activity was 49.4 mg/ml

and 103 μg/ml, respectively. The scavenging ability to hydroxyl radical was 4.8 times

weaker than vitamin C. By the method of DPPH assay, the EC50 of the quenching

DPPH was 19.6 mg/ml. Antioxidant activity of ethanol extract (1mg/ml) was

equivalent to 50 μM vitamin C evaluated by ferric reducing antioxidant power

(FRAP) assay. The measurement of the resistance of low density lipoprotein (LDL)

to oxidation promoted by copper ion ex vivo, LDL prepared from

hypercholesterolemic rabbits supplemented with orally 100 mg/kg/day Pueraria

mirifica (P.mirifica-group) for 12 weeks showed a significantly decreased

susceptibility to Cu²⁺-mediated oxidation ex vivo, compared with

hypercholesterolemic rabbits with no supplementation (Chol-group). The lag time

was prolonged from 115.6 ± 9.7 min in Chol-group to 160.4 ± 6.6 min in P.mirifica-group.

These data demonstrate that although, Pueraria mirifica had mild

antioxidative activity in the in vitro experiment. However, it could increased the

resistance to oxidation of LDL ex vivo. Our results may provide the beneficial effect

of Pueraria mirifica for the cardiovascular system which required further

experimental and clinical studies.