Study of DNA Damage of Fibroblasts Induced by Ultraviolet-B Irradiation and the Photoprotective Effect of (-)-epigallocatechin-3-gallate and Baicalin

Objective To investigate the production and removal of cyclobutane pyrimidine dimers(CPDs) induced by UVB irradiation and intervention effect by epigallocatechingallate(EGCG) in human fibroblasts.Methods Fibroblasts were irradiated only by UVB or treated with EGCG or baicalin.The production and removal of CPDs at different time intervals were examined by immunohistochemical method.Results The damage of fibroblasts was increased in the dosage of UVB irradiation.CPDs appeared in fibroblasts and reached the peak in 1 h and removed rapidly during the first 4 h and then removed slowly or almost cleared out up to 24 h after UVB irradiation.The quantity of CPDs was decreased when irradiated fibroblasts were incubated with EGCG or baicalin(P0.05).Conclusion UVB irradiation induced the production of CPDs;the photodamage of fibroblasts was UVB dose dependent;DNA lesions could be repaired by cell itself;EGCG and baicalin could decrease the level of CPDs.