Protective effect of the Baicalin against DNA damage induced by ultraviolet B irradiation to mouse epidermis

Purpose: To investigate whether topical application of Baicalin affords protecting Balb/C mice epidermis from ultraviolet (UV)B-induced DNA damage and its underlying mechanisms. Methods: A DNA damage model of UVB irradiation-induced mice epidermis was established. The immunohistochemical staining, Southwestern dot-blotting were used for cyclobutane pyrimidine dimers (CPDs) detection; Western blotting was used for p53 detection; reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the mRNA level of Bcl-2 and Pax; terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) was used to detect apoptotic cells. Results: Topical application of Baicalin on Balb/C mice skin significantly decreased the amount of epidermal CPDs 1, 24 and 48 h after 180 mJ/cm(2) of UVB irradiation as compared with untreated mice. UVB-induced apoptosis was less pronounced in Baicalin-treated mice epidermis, which was accompanied by less p53 accumulation and higher Bcl-2/Bax ratio compared with that of untreated mice. Conclusion: Taken together, these results suggest that topical Baicalin application mitigates DNA photo-damage. Baicalin is therefore a promising protective substance against UVB radiation.