Prevention of UV radiation-induced cutaneous photoaging in mice by topical administration of patchouli oil

Pogostemon cablin has been widely used in traditional Chinese medicine for the treatment of many diseases, including skin disorders. In the skin beauty and care prescriptions, Pogostemon cablin is one of the top ten frequently used traditional Chinese medicines.The present study was aimed to investigate the protective effects of the essential oil of Pogostemon cablin (patchouli oil, PO) against UV-induced skin photoaging in mice.To ensure the quality of PO, the chemical compositions of PO were identified, and the content of its chemical marker patchouli alcohol was determined, which was around 28.2% (g/g) in PO. During the experiment period, the dorsal depilated skin of mice was treated with PO for two hours prior to UV irradiation. Then the protective effects of PO on UV-induced skin photoaging were determined by macroscopic and histological evaluations, skin elastic test, collagen content determination and biochemical assays of malondiaidehyde (MDA) content, activities of anti-oxidative indicators including superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT).Compared to UV exposure groups, present results showed that topical administration of PO, especially at dose of 6mg/mouse and 9mg/mouse, significantly inhibited the increase in skin wrinkle formation, alleviated the reduction in skin elasticity and increased the collagen content by about 21.9% and 26.3%, respectively. We also found that application of 6–9mg/mouse PO could not only decrease the epidermal thickness by about 32.6%, but also prevent the UV-induced disruption of collagen fibers and elastic fibers. Furthermore, the content of MDA was decreased by almost 26.5% and activities of SOD, GSH-Px and CAT were significantly up-regulated after the treatment of PO.Results of present study revealed that PO was capable of maintaining skin structural integrity caused by UV irradiation and it was useful in preventing photoaging. These protective effects of PO were possibly due to its anti-oxidative property. Therefore, we suggested that PO should be viewed as a potential therapeutic agent for preventing photoaging.