Antiphotoaging Potential of Extracts of Yin-Tonic Herbal Medicine in Skin Cell and Human Skin Equivalent

Yin-tonic herbal medicines have been shown to possess properties that make skin healthy by nourishing within various organs of the body. However, the antiphotoaging effect of these medicines on the skin has not been fully studied. Photoaging occurs with prolonged sun exposure and causes skin damage and aging, with depletion of the dermal extracellular matrix and chronic alterations in skin structure, such as wrinkles. In this study, we assessed the antiphotoaging effects of eight yin-tonic herbal medicines on human skin cells and skin equivalents. The levels of type I procollagen and matrix metalloproteinase-1 (MMP-1) in ultraviolet B- (UVB-) irradiated CCD-986sk fibroblasts were measured, and then three medicines were chosen based on screening results. Using UVB-irradiated human skin equivalents, we evaluated the effect of three yin-tonic herbal medicines on histological changes of skin, epidermal and dermal thickness, and MMP-1 production. Furthermore, we observed collagen fiber content and protein expression of filaggrin in UVB-irradiated human skin equivalents. Yin-tonic herbal medicines increased type I procollagen levels and decreased the production of MMP-1 in UVB-irradiated CCD-986sk fibroblasts. The three selected yin-tonic herbal medicines recovered the collagen content and filaggrin expression via MMP-1 downregulation in UVB-irradiated human skin equivalents. Our results show that yin-tonic herbal medicines can prevent skin photoaging by reduction of MMP-1 levels and increasing the expression of moisturizing factors. Based on these results, we suggest that yin-tonic herbal medicines have the potential to be used as helpful agent for skin photoaging.