Photoprotective effect of quercetin on photoaging in rats

Photoaging; is a skin disease which forms the basis of the external factor of aging and can affect the whole society. It is characterized by lentigo, telangiectasia, mottled pigmentation, coarsening of the skin, loss of transparency, pale and dull skin color, laxity, elasticity and turgor decrease. Photoaging has a complex pathogenesis mechanism. Photoaging is not desired due to the fact that it can be the cause of skin cancers and poor cosmetic outcomes and it is treated with unproven, uneffective rejuvenation procedures that costs money and time. In this study, our aim was to search the effects of quercetin treatment on photoaging model, that is created using an UVA lamp with an emition spectrum of 315 to 380 nm through using histopathological, biochemical and clinical parameters. In our study, 40 rats were randomly divided into 5 groups. Other than the negative control group, each group was subjected to UVA for 5 days a week for 8 weeks, in order to create photoaging model. In addition to UVA exposure, one of the groups had %0.1 retinoic acid, another had %0.3 quercetin and a third one had both %0.1 retinoic acid and %0.3 quercetin applied for 5 days a week for 8 weeks. At the eighth week, all of the groups had significant increase in clinical wrinkling, epidermal thickness, hyperkeratosis, acanthosis, collagen damage and inflamation compared to the negative control group. These findings were coherent with the current literature. Depending on these findings the creation of photoaging model was confirmed. Significant decrease in clinical wrinking was observed in Retinoic acid, Retinoic acid with Quercetin and Quercetin only groups although the groups with Retinoic acid had further decrease in clinical wrinkling. Between the groups with retinoic acid, retinoic acid with quercetin had further decrease in wrinkling, though the difference was statistically insignificant. Quercetin, Retinoic Acid and Retinoic acid with Quercetin groups had decreased levels of inflammation, hyperkeratosis and collagen damage compared to UVA-only group. When all groups were compared, differences in parakeratosis, ROS parameters for biochemical marker, vacuolisation and spongiosis levels were statiscally unsignificant. MMP-1 levels were statistically elevated in Retinoic acid, Retinoic acid with Quercetin, Quercetin and UVA-only groups, with more increase in Retinoic acid and Retinoic acid with Quercetin groups. We think that this increase can be explained by the hypothesis that retinoic acid and quercetin treatments play a role in the regeneration of the extracellular matrix. In conclusion, in the light of new data, topically administered quercetin can be perceived as an effective molecule in treatment of photoaging by decreasing inflammation, keratinization and collagen damage both with and without retinoic acid.