Anti-inflammatory activity of the soybean methanolic fraction containing isoflavones

Soybeans are used extensively as a food to prevent diseases of aging. The main compounds reported are isoflavones, which can inhibit different mediators of the inflammatory response [1]. A methanolic fraction containing isoflavones was obtained from conventional soybean seeds. This fraction was analysed by high-performance liquid chromatography (HPLC). It was assayed for acute toxicity and anti-inflammatory activity in the inflammation experimental model using croton oil-induced ear oedema. The methanolic fraction was found to contain daidzin, glycitin, genistin, malonyldaidzin, malonylglycitin, malonylgenistin, daidzein, glycitein, and genistein at (145.67±3.14), (47.69±1.86), (147.54±5.54), (276.54±4.21), (105.73±1.17), (466.54±7.37), (57.73±1.26), (22.61±0.36), (75.04±1.61) respectively, a total of 1345.09mg/100g. The methanolic fraction at doses of 0.625, 1.25, and 2.5mg/kg significantly inhibited ear oedema compared to the control group. The inhibition percentages were, respectively: 44.23% (p<0.05), 60.68% (p<0.01), 65.68% (p<0.01). The activity of the enzyme myeloperoxidase decreased (64.79%, p<0.05). These results showed that the methanolic fraction containing soy isoflavones possessed anti-inflammatory activity in this experimental model. There was no acute toxicity in Swiss mice (25–35g) that received the fraction orally or intraperitoneally at doses of 1000, 2000, 3000, and 4000mg/kg.

Acknowledgements: This study was supported through grants from the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and CAPES.

Reference: 1. Djsselbloem, N. et al. (2004) Biochem Pharmacol. 68:1171–1185.