Protective effects of quercetin on UVB irradiation‑induced cytotoxicity through ROS clearance in keratinocyte cells.

Human skin is the body's largest organ that protects against diverse environmental injuries. However, ultraviolet (UV) radiation, which induces a transient increase in the intracellular level of reactive oxygen species (ROS) and leads to a variety of injuries and various skin diseases, has deleterious effects on living organisms. Quercetin is a naturally occurring compound with strong antioxidant action and can successfully scavenge free radicals. In the present study, we investigated the effects and the mechanism of quercetin on UVB‑induced cytotoxicity in keratinocyte (HaCaT) cells. The results of this study showed that quercetin (20 μM) significantly blocked UVB irradiation (15 mJ/cm2)‑induced intracellular ROS generation. In addition, the ROS clearing ability of quercetin prevented cell membrane and mitochondria from ROS attack and inhibited cell membrane fluidity decrease and mitochondrial membrane depolarization. Moreover, the outflow of cytochrome c and apoptosis were markedly inhibited. These results suggest that the protective effect of quercetin against UVB irradiation‑induced toxicity is mainly mediated by the ROS scavenging ability. Thus, quercetin is a potential agent against UVB irradiation‑induced skin damage.