This study was conducted in order to evaluate the alleviating effects of Phellodendrin cortex water extract (PCWE) on skin aging in hairless mice via observation of morphogical and histological changes. Skin aging was induced by UVB irradiation and application of squalene monohydroperoxide (Sq-OOH) to the back skin of hairless mice for six weeks. And, at the same time, saline (C), jojoba oil (VC), PCWE (E), and 0.01% retinoic acid diluted with polyethylene glycol (PC) were applied topically twice per day, six days per week, for a period of six weeks. Improved wrinkle formation in a pattern of shallow furrows and thin and narrow crests was observed in the retinoic acid and PCWE application groups, compared to the C group. On the morphologic analysis for skin wrinkles, the E group showed lower levels in skin roughness, maximum roughness, average roughness, smoothness depth, and arithmetic average roughness by 13.1, 17.2, 18.4, 15.4, and 16.1%, respectively, compared with the C group, indicating that PCWE inhibited potential formation of wrinkles in the skin. In the C group, structures of lipid lamellae and collagen fibers were broken or deformed with an irregular arrangement. Application of retinoic acid and PCWE protected against the deformity of lipid lamellae and collagen fibers. Elastic fibers in dermis of the C group also showed severe transformation; however, applications of retinoic acid and PCWE resulted in a significant decrease in the number of denatured elastic fibers. Therefore, PCWE could have an alleviating effect on skin aging induced by UVB irradiation and application of Sq-OOH.

This study was conducted for evaluation of the alleviating effects of Phellodendrin cortex water extract (PCWE) on skin inflammation in hairless mice. Skin inflammation was induced by UVB irradiation and application of squalene monohydroperoxide (Sq-OOH) to the back skin of hairless mice for six weeks. At the same time, saline (C), jojoba oil (VC), PCWE (E), and 0.01% retinoic acid diluted with polyethylene glycol (PC) were applied topically twice per day, six days per week for a period of six weeks. The skin erythema index of the E group was lower than that of the C group. Epidermis and dermis of the C group were remarkably thickened, compared to the PC or E group. In the C group, infiltration of many inflammatory cells, including neutrophils and lymphocytes, was observed in dermis, and a large number of mast cells were observed in dermis and hypodermis; the degree of degranulation was remarkable. However, these phenomena were alleviated in the PC and E2 groups. The E group showed a lower activity in skin xanthine oxidase but a higher activity in skin superoxide dismutase, compared to the C group (P<0.05). The VC, PC, and E groups also showed a high activity of skin catalase by 25.3%, 58%, and 42%, respectively, compared to the C group. Taken together, these results indicate that PCWE could have an alleviating efficacy on skin inflammation induced by UVB irradiation and application of Sq-OOH in hairless mice.