Abstract:

Objective To investigate the formation and elimination of photoproduct in epidermal cells from BALB/c mice irradiated with ultroviolet B, and to observe the interference by baicalin in it. Methods BALB/c mice were randomized into 6 groups, i.e., blank control group receiving no exposure or protection, baicalin group receiving protection with baicalin, acetone group receiving acetone pretreatment, UVB group receiving UVB irradiation but no protection, UVB + baicalin group receiving UVB irradiation and protection with baicalin, UVB + acetone group receiving acetone pretreatment and UVB irradiation. Baicalin was applied at 1 mg/cm2 on the back of mice for 3 days in baicalin group and UVB + baicalin group. Twenty hours after the last application, UVB irradiation of 180 mJ/cm2 was given to mice in UVB group and UVB + baicalin group. Skin specimens were obtained from the tested sites at 1, 24, and 48 hours, respectively, after the irradiation. Cyclobutane pyrimidine dimers （CPD） was detected in the specimens with immunohistochemical staining and Southwestern dot blotting. Results CPD was observed only in irradiated mice. The relative content of CPD in epidermal cells 1, 24 and 48 hours after the irradiation was （100 ± 5.22)％, （75.34 ± 8.22）％ and （42.11 ± 3.24）％, respectively, in UVB group, （81.45 ± 5.22）％, （32.14 ± 6.33）％ and （5.21 ± 3.15）％ respectively, in UVB+baicalin group, （106 ± 8.21）％, （70.23 ± 4.13）％ and （41.22 ± 4.21）％, respectively, in UVB + acetone group. A significant difference was observed in the relative content of CPD between UVB group and UVB + baicalin group at 1, 24 and 48 hours after the irradiation （P < 0.05, 0.01, 0.01, respectively）. Conclusions Taken together, these results suggest that topical baicalin application mitigates DNA photo-damage. Baicalin is therefore a promising protective substance against UVB radiation.

Key words: Baicalin;cyclobutane pyrimidine dimers;ultraviolet B