The Mechanism Of Quercetin Protecting Skin From UV Damage

Skin is the largest human organ.Skin continually reconstructs itself to ensure its viability,integrity,and ability to provide protection for the body.Some areas of skin are continuously exposed to a variety of environmental stressors that can inflict direct and indirect damage to skin.A variety of environmental stresses,particularly UV light,can damage sun-exposed areas of the skin,such as the face and neck,and accelerate premature aging.In addition,UV has harmful effects and leads to different skin disorders such like sunburn,erythema,inflammation,oxidative damage,etc.Thus,we focus more and more on the protective effect of research about UV.Although quercetin was described to have a potential as an active compound for protection against UV-irradiated skin damage,the detailed function and molecular mechanism of quercetin against UVA and UVB-induced skin damage were still unclear.In this study,we investigate systematically the protective effects of quercetin on UVA or UVB-induced skin damage and aging in vitro and in vivo.We found that quercetin treatments significantly reversed UVA and UVB-induced cell apoptosis,oxidative stress,inhibition of cell viability,and reduction of antioxidant capacity as well as the overexpressions of inflammatory cytokines and COX-2 in the skin fibroblasts in a dose-dependent manner.In an animal model,topical quercetin treatment was also effective in protecting mouse skin from UVA and UVB-induced skin damage.Moreover,quercetin reversed not only the increase of MMP-1,MMP-2 and MMP-9 after UVA and UVB irradiation but also the decrease of type I collagen.We also demonstrated that quercetin treatments blocked the activation of p38 MAPK and JNK MAPK signal pathways induced by UVA and UVB in vitro and in vivo.Thus,our findings suggest that quercetin has a dual function of anti-photodamage and anti-photoaging in skin by regulating p38 MAPK and JNK MAPK signal pathway.We propose that quercetin may be applied as an effective and novel drug for resisting photo-damage and photoaging and it may be a possible content in sunscreen and anti-aging cosmetics.