The Protective And Therapeutic Effects Of Resveratrol On Solar Simulated Ultraviolet Irradiation Induced Photodamage

ObjectiveOverexposure to the solar ultraviolet irradiation (UVR) results in photodamage to the skin, including erythema, edema, hyperpigmentation, sunburn cells formation, immunosuppression, and skin cancer. Resveratrol is well known for its potent ability of anti-inflammation, antioxidant, inhibition of platelet aggregation and cancer cell growth. The present study was designed to investigate the protective and therapeutic effects of resveratrol on solar simulated ultraviolet irradiation (ssUVR)-induced photodamage.Materials and Methods1. SubjectsTwenty healthy Chinese female volunteers with a Fitzpatrick photo type of IV were enrolled in this study. Each volunteer signed an informed consent.2. MethodsTwelve non-exposed sites on the left and right upper back were marked for the experiment. Sites 1-4 on the left back were applied with the test materials (resveratrol+antioxidant:ResAox; antioxidant:Aox; resveratrol:Res and vehicle:Veh, respectively), followed by ssUVR at a dosage of 1.5 MED 30 minutes later. Sites 1-4 on the right back were exposed to 1.5 MED ssUVR first, and then immediately coated with the same test materials as on the left back. Sites 5 on both back received only ssUVR (UVonly) without any test material (positive control). Sites 6 on both back received neither ssUVR (Sham) nor test materials (negative control). L* value, a* value,b* value and ITA°value were assessed pre-and post-procedure. The subjects exposure to ssUVR once a day for 4 days.The skin biopsies were taken 24 hours after the last ssUVR. The specimens were stained with hematoxylin eosin (HE) staining, Fontana Manna staining and CD1a immunohistochemical staining.3. Statistical analysisSPSS 16.0 was used in the statistics. The data which correspond to normal distribution were analyzed using analysis of variance. P-value<0.05 was considered statistically significant.1. Erythema, L* value, a* value and ITA°valueAfter ssUVR, obvious erythema were developed on positive control sites (UVonly) and vehicle control sites (VehUV) on both back, L*values and ITA°values decreased dramatically, a* value increased notably; Whereas on ResAoxUV sites and ResUV sites, erythema was barely seen with moderate decrease of L* values, ITA°values and slight increase of a* values. There was a remarkable difference between the two treated sites and the two control sites (P<0.05).2. Epidermal thicknessAfter ssUVR, the epidermal thickness increased more significantly on UVonly sites and VehUV sites, than on ResAoxUV sites, AoxUV and ResUV sites (P<0.05).3. Sunburn cells (SBCs)After ssUVR, more SBCs were observed in the epidermis on the UVonly sites and VehUV sites than on the ResAoxUV sites, AoxUV sites and ResUV sites (P<0.05).4. Melanin Content Index (MCI)After ssUVR, the measured percentage (%) and average optical density of MCI increased significantly on UVonly sites and VehUV sites, much higher than on ResAoxUV sites, AoxUV sites and ResUV sites (P<0.05). 5. Langerhans cellAfter ssUVR, the density of Langerhans cells decreased dramatically on UV only sites and VehUV sites, however, Compared with UV only sites and VehUV sites, there is a mildly decrease on ResAoxUV sites, AoxUV and ResUV sites (P<0.05).ConclusionResveratrol or resveratrol combined with anti-oxidants can be effective in preventing and repairing ssUVR-induced skin color changes (skin erythema, L* values, ITA°values decrease and a* values increase), epidermal edema, sunburn cell formation, melanin formation and Langerhans cells decrease.