Study on Antioxidant Activity of Phytoestrogen Extracts From Soy Germ

Abstract

Soy germ is one of the richest phytoestrogen sources and thus has many benefits for health such as improving bone density, cardiovascular health, cancer prevention, and menopausal treatment. In addition, phytoestrogens are reported to act as antioxidants, removing reactive oxygen species and thereby preventing oxidative damage in living tissue. Phytoestrogens in soy germ include isoflavone compounds and their derivatives: daidzein, genistein, glycitein, daidzin, genistin, glycitin, acetyl daidzin, acetyl genistin, acetyl glycitin, malonyl daidzin, malonyl genistin, malonyl glycitin. Isoflavones aglycone forms comprise only about 2-5% of total isoflavones, however, they express more biological effects than the others. The objective of this study was to compare the antioxidant activity among three extracts: purified isoflavone aglycone extract, crude isoflavone aglycone extract and total phytoestrogen extract. The IC50 value of DPPH free radical scavenging capacity of purified isoflavone aglycone extract, crude isoflavone aglycone extract and total phytoestrogen extract were 0.763 ± 0.016; 3.345 ± 0.076; 6.142 ± 0.050 mg/ml, respectively. The IC50 value of reducing power activity of purified isoflavone aglycone extract, crude isoflavone aglycone extract and total phytoestrogen extract were 1.248 ± 0.024; 3.961 ± 0.172; 9.385 ± 0.272 (mg/ml). As our result, the ranking order of the antioxidant activity (from highest to lowest level) was purified isoflavone aglycone extract > crude isoflavone aglycone extract > total phytoestrogens extract.