Protective effects of polymethoxyflavone-rich cold-pressed orange peel oil against ultraviolet B-induced photoaging on mouse skin. (April 2020) - Li, Guijie
Graphical abstract: Highlights: Orange cold-pressed oil (CPO) protects mouse skin from UVB-induced oxidative damage. CPO helps to maintain collagen normality by regulating TIMP 1&2 and MMP 2&9. 5-hydroxy products found as UVB degradation of topical polymethoxyflavones (PMFs). PMFs and hydroxy-PMFs play important part in the anti-photoaging effects of CPO. Abstract: The protective effects of the topical application of orange peel cold-pressed oil (CPO), a rich polymethoxyflavones (PMFs) source, on ultraviolet B (UVB)-induced skin injury were studied. Depilated KM mice were irradiated by UVB at one minimal erythemal dose every day and the treated groups were smeared with CPO before radiation. After two weeks we found that CPO helped to maintain the dermal structure and enhanced serum levels and skin tissue expression of superoxide dismutase, catalase and glutathione peroxidase. In serum CPO lowered interleukin-6/-1β and tumor necrosis factor α levels; in skin it decreased the levels of type III collagen and H2 O2 but increased hydroxyproline and type I collagen. Moreover, the skin expression of matrix metalloproteinases 2/9 was downregulated, whereas the expression of tissue inhibitor of metalloproteinases 1/2 was upregulated. The above effects followed a dose-dependent manner. Liquid chromatography analysis of irradiated skin tissue showed partial decomposition of PMFs into 5-hydroxy-PMFs.