Histological investigation of the effect of soybean (Glycine max) extracts on the collagen layer and estrogen receptors in the skin of female rats

OBJECTIVES The purpose of this study was to analyze the effects of soybean extracts obtained using different extraction methods on the skin of female rats. METHOD A total of 64 female Sprague-Dawley rats were divided into 8 equal groups. Various extracts were administered to the female rats by oral gavage for one month. The groups comprised carboxymethyl cellulose-free control, carboxymethyl cellulose-plus control, 100-mg/kg n-hexane extract, 200-mg/kg n-hexane extract, 100-mg/kg ethyl acetate extract, 200-mg/kg ethyl acetate extract, 100-mg/kg ethanol extract and 200-mg/kg ethanol extract groups. The thickness of the collagen layer and the number of estrogen receptor-positive cells were evaluated. RESULTS All the extract-treated groups showed a statistically significant decrease in the number of estrogen receptor-positive cells compared with the control groups. Regarding the thickness of the collagen layer, only the 200-mg/kg ethyl acetate extract-treated group showed a significant increase compared with the control groups (p<0.05). CONCLUSIONS Our data suggest that oral intake of three different total soybean extracts might have positive estrogenic effects on the skin and that only a high-dose ethyl acetate extract can increase the expression of collagen, which may prove to be beneficial for postmenopausal facial skin.