BACKGROUND/AIMS: Dietary antioxidants exert a photoprotective effect against UV radiation. However, the mechanism underlying the beneficial effects on skin of orally administered antioxidant is not very clear. The present study aimed to investigate the UVB-induced total antioxidant capacity (TAC) perturbation both in skin and blood and to study the beneficial mechanism of action of dietary epigallocatechin-3-gallate (EGCG). METHOD: Female HWY/Slc hairless rats were exposed to UVB radiation for 4 weeks and skin and blood TAC were measured at weeks 0, 2, and 4. The correlation between skin and blood TAC was assessed using Pearson's correlation analysis. To investigate the effect of dietary EGCG, female HWY/Slc hairless rats were fed EGCG and exposed to UVB radiation. At the end of the 8-week experimental period, transepidermal water loss (TEWL) and epidermal thickness were measured to assess skin damage, and TAC was analyzed in both skin and blood. RESULTS: UVB radiation significantly decreased skin and blood TAC, and there was a significant correlation between skin and blood TAC. Dietary EGCG significantly prevented UVB-induced adverse effects on epidermal thickness and TEWL, and the UVB-induced decrease in TAC recovered in both skin and blood. CONCLUSION: These results demonstrate that there is a close relationship between skin and blood TAC and the beneficial effect of oral antioxidants on skin may possibly be mediated through significant enhancement of blood TAC. Copyright 2010 S. Karger AG, Basel.
BACKGROUND/AIMS: Dietary antioxidants exert a photoprotective effect against UV radiation. However, the mechanism underlying the beneficial effects on skin of orally administered antioxidant is not very clear. The present study aimed to investigate the UVB-induced total antioxidant capacity (TAC) perturbation both in skin and blood and to study the beneficial mechanism of action of dietary epigallocatechin-3-gallate (EGCG). METHOD: Female HWY/Slc hairless rats were exposed to UVB radiation for 4 weeks and skin and blood TAC were measured at weeks 0, 2, and 4. The correlation between skin and blood TAC was assessed using Pearson's correlation analysis. To investigate the effect of dietary EGCG, female HWY/Slc hairless rats were fed EGCG and exposed to UVB radiation. At the end of the 8-week experimental period, transepidermal water loss (TEWL) and epidermal thickness were measured to assess skin damage, and TAC was analyzed in both skin and blood. RESULTS: UVB radiation significantly decreased skin and blood TAC, and there was a significant correlation between skin and blood TAC. Dietary EGCG significantly prevented UVB-induced adverse effects on epidermal thickness and TEWL, and the UVB-induced decrease in TAC recovered in both skin and blood. CONCLUSION: These results demonstrate that there is a close relationship between skin and blood TAC and the beneficial effect of oral antioxidants on skin may possibly be mediated through significant enhancement of blood TAC. Copyright 2010 S. Karger AG, Basel.