Abstract
It is known that solar ultraviolet (UV) radiation to human skin causes photo-aging, including increases in skin thickness and wrinkle formation and reduction in skin elasticity. UV radiation induces damage to skin mainly by superfluous reactive oxygen species and chronic low-grade inflammation, which eventually up-regulate the expression of matrix metalloproteinases (MMPs). In this study, the super-critical carbon dioxide extract from flowers and buds of Chrysanthemum indicum Linnén (CISCFE), which has been reported to possess free radical scavenging and anti-inflammatory properties, was investigated for its photo-protective effect by topical application on the skin of mice. Moreover, CISCFE effectively suppressed the UV-induced increase in skin thickness and wrinkle grading in a dose-dependent manner, which was correlated with the inhibition of loss of collagen fiber content and epidermal thickening. Furthermore, we observed that CISCFE could obviously decrease UV-induced skin inflammation by inhibiting the production of inflammatory cytokines (interleukin-1β [IL-1β, IL-6, IL-10, tumor necrosis factor-α), alleviate the abnormal changes of anti-oxidative indicators (superoxide dismutase, catalase, and glutathione peroxidase), and down-regulate the levels of MMP-1 and MMP-3. The results indicated that CISCFE was a novel photo-protective agent from natural resources against UV irradiation.