Morphological and Histological Changes in Photoaged Hairless Mice Induced by Phellodendrin cortex Water Extract Application

This study was intended to evaluate the alleviating effects of Phellodendrin cortex water extract (PCWE) on skin aging in hairless mice via observing morphogical and histological changes. Skin aging was induced by UVB irradiation and squalene monohydroperoxide (Sq-OOH) application to the back skin of hairless mice for 6 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 a day, 6 days a week for 6 weeks. Retinoic acid and PCWE application groups improved wrinkle formation in a pattern of shallow furrows and thin and narrow crests compared to the C group. As based on the morphologic analysis for skin wrinkles, 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 than the C group, indicating that PCWE inhibited potential formation of wrinkles in the skin. The structure of lipid lamellae and collagen fibers were broken or deformed with an irregular arrangement in the C group. The retinoic acid and PCWE applications protect against the deformity of lipid lamellae and collagen fibers. Elastic fibers in dermis of the C group were also transformed severely but applications of retoinoic acid and PCWE significantly decreased the number of denatured elastic fibers. Therefore, PCWE could have a alleviating effects on the skin aging induced by UVB irradiation and Sq-OOH application.