Photoprotective Effects of Soybean Extract against UV-Induced Damage in Human Fibroblast and Hairless Mouse Model

Abstract

Soy isoflavones have been reported to possess many physiological activities such as antioxidant activity and inhibition of cancer cell proliferation. This study investigated the photoprotective effects of soybean extract in human fibroblast cell line and hairless mice model. Human fibroblast was treated with soybean extract before and after ultraviolet B (UVB; 290-302 nm) irradiation. In the soybean extract treated group, the cells showed better resistance to ultraviolet (UV) than control group. The amount of type I collagen recovered from the soybean treated group was higher than the vehicle group exposed to UV-induced damage. Moreover, increased expression of metalloproteinases-1 as a result of UV irradiation was suppressed by the soybean extract. Female mice were orally administered soybean extract and irradiated with UVB light for 8 weeks. The effects of the soybean extract on the skin appearance, collagen deposition and epidermal thickness in the UV-damaged mouse skin were analyzed using histopathological methods. In soybean extract treated group, the skin had a better morphology than that of the control group. Furthermore, the amount of type I collagen was increased and overexpression of MMP-1 was reduced in the soybean extract group compared to vehicle group. Additionally, up-regulation of pro-inflammatory cytokines induced by UV irradiation was suppressed by dietary soybean extract treatment. It appears that soybean extract had a photoprotective effect, including anti-aging and anti-inflammatory effect, from UV-induced damage in not only human fibroblast, but also hairless mice. We confirmed that these effects were possibly due to promotion of collagen synthesis and inhibition of MMP-1 expression.