Protective effects of dietary soy isoflavones against UV-induced skin-aging in hairless mouse model

Objective: This study investigated the anti-aging effects of dietary isoflavone:; on photoaged hairless mouse skin. Methods: Female hairless mice were administered soy isoflavone extract orally and irradiated with UV light for four weeks. The effects of the isoflavones on the skin appearance, collagen deposition and epidermal thickness in the UV-damaged mouse skin were measured using bioengineering and histochemical methods. In addition, the influence of the isoflavones on the collagen metabolism in the UVB-irradiated human skin fibroblasts was also investigated. Results: In the isoflavone treated group, the skin had a better appearance and less wrinkling than that of the control group. Additionally, the amount of collagen deposition was higher in the isoflavone group. In the human fibroblast cells, the amount of procollagen de novo synthesized did not increase after isoflavone treatment and/or UV irradiation. However, the increase in the expression of the metalloproteinases (MMPs) as a result of UV irradiation was suppressed by the isoflavone treatment. Conclusions: It appears that isoflavones had an anti-aging effect on the UV-damaged hairless mice model, which is partly due to the inhibitory effects on UV-induced MMP-1 expression and the subsequent collagen degradation.