ANTIOXIDATIVE EFFECT OF PUERARIA MIRIFICA

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 ug/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 Cup-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 increase 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.

Sanvarinda, L. Phivthong-ngam, SK. Wattanapitayakul, M. Yajima, HO. Murakami, A. Apisariyakul, T. Suwancharas
Department of Pharmacology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
Department of Pharmacology, Faculty of Medicine, Srinakharinwirot University,Bangkok 10110, Thailand.
Department of Pharmacology, Aichi Medical University, Nagakute, Aichi, 4801 195,Japan
Department of Pharmacology, Faculty of Medicine, Chiang Mai University, ChiangMai 50200, Thailand.
Department of Surgery, Faculty of Medicine, Srinakharinwirot University, Bangkok 10110, Thailand.

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