Evaluation of soybean methanol fraction on acute inflammation.

Soybeans have been of interest of researchers because of the presence of isoflavones, a subclass of flavonoids, which have demonstrated anti-inflammatory activity. The aim of this study was investigate the anti-inflammatory activity of the methanol fraction from soybean, which contains mainly isoflavone glucosides and malonylglucosides. The anti-inflammatory activity of the methanol fraction from soybean was studied using croton oil-induced mouse ear edema and carrageenan-induced pleurisy models. The methanol fraction inhibited the ear edema in a dose-dependent manner: 0.625 mg/kg by 44.23% (P<.05), 1.25 mg/kg by 60.68% (P<.01), and 2.5 mg/kg by 65.68% (P<.01). Myeloperoxidase enzyme activity was reduced at the dose of 2.5 mg/kg (64.79%, P<.05). No effects were seen on carrageenan-induced pleurisy at different doses of the methanol fraction (100 or 400 mg/kg). These results demonstrated that the methanol fraction containing conjugated isoflavones showed topical anti-inflammatory activity. There was no acute toxicity in Swiss mice after oral administration of the fraction, at doses of 1,000, 2,000, 3,000, and 4,000 mg/kg.