599 Melatonin delays UV-induced premature senescence in human skin fibroblasts

Melatonin (N-acetyl-5-methoxytryptamine), an indolamine produced in pinealis gland, is the main human molecule involved in the circadian rhythms regulation, reaching maximum concentration levels during the night and under darkness. Melatonin is widely distributed to all body tissues, and in addition to its circadian effects, it has several other biological effects such as antioxidant effect, anti-inflammatory effect and protection to nuclear and mitochondrial DNA. Due to these properties, we hypothesized that melatonin would have the potential to reduce or to delay the appearance of molecular markers related to the premature cell aging. Results of flow cytometry and western blotting experiments showed that melatonin is able to reduce senescence-associated β-galactosidase, p16, p21 and IL-8 expression in human fibroblasts submitted to an UV-induced premature senescence protocol. Inducing suitable levels of topical nocturnal melatonin may be a promisor strategy for anti-aging cosmetics, especially for people exposed to excessive artificial light during the night.