ABSTRACT
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 Bax; 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.
Subject(s)
DNA Damage/drug effects , Epidermis/drug effects , Epidermis/radiation effects , Flavonoids/pharmacology , Plant Extracts/pharmacology , Scutellaria baicalensis , Ultraviolet Rays/adverse effects , Administration, Cutaneous , Analysis of Variance , Animals , Apoptosis/drug effects , Apoptosis/radiation effects , DNA/analysis , Epidermis/metabolism , Epidermis/physiology , Female , Mice , Mice, Inbred BALB C , Proto-Oncogene Proteins c-bcl-2/genetics , Proto-Oncogene Proteins c-bcl-2/metabolism , Pyrimidine Dimers/metabolism , RNA, Messenger/analysis , Tumor Suppressor Protein p53/metabolism , bcl-2-Associated X Protein/genetics , bcl-2-Associated X Protein/metabolismABSTRACT
Objective To observe the damage to Langerhans cells induced by UVB irradiation,and to evaluate photoprotective effect of these cells from UVB irradiation by epigallocatechin-3-gallate (EGCG).Methods Biopsy specimens were obtained from normal adult foreskin,and epidermal cells were isolated.Density gradient centrifugation and magnetic cell sorting were used simultaneously to purify Langerhans cells from the cell suspension.These cells were then divided into three groups,control (no ir- radiation or EGCG treatment),UVB (irradiation) and EGCG (irradiation+ECCG treatment) groups. The cells in the UVB and EGCG group were irradiated by UVB (30 mJ/cm~2).After the irradiation,the U- VB group was incubated with RPMI-1640 containing 10% bovine serum for 4 hours,while the EGCG group with the same medium containing 200?g/mL of EGCG for 4 hours.Another four hours after the treatment, the cells were collected for the detection of apoptosis rate by propidium iodide staining and flow cytometry. Results Exposure to UVB (30 mJ/cm~2) significantly increased the apoptotic rate of Langerhans cells.The apoptotic rate in EGCG group was significantly lower than that in the UVB group,but was higher than that in the control group.Conclusion Rate of apoptosis of Langerhans cells could be increased by UVB irradia- tion,while EGCG could prevent the increase of apoptosis.
