Abstract:To compare the photo-protective effect of green and black tea extracts on HaCaT cells damaged from ultraviolet radiation B. Sub-confluent HaCaT cells were incubated for 6 h with different doses of extracts from green tea and black tea, and then irradiated with 60 mJ/cm2 doses of UVB. The change of the cell viability, the activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), lactate dehydrogenase (LDH), and the level of malondialdehyde (MDA) of supernatant were compared. The content of ROS was measured with the fluorescence method. Annexin V/PI double staining was performed to evaluate the change of apoptosis using flow cytometry. In addition, the contents of tea polyphenols and catechins from extracts of green and black tea were also tested. The results were as follows: Compared with control group, the UVB irradiation could seriously harm HaCaT cell and gave rise to 21.61% cell viability decline. Extracts form green and black tea could enhance cell viability, SOD and GSH-Px activity in supernatant under UVB irradiation, and decrease LDH activity , the content of MDA and the content of ROS in cells in dose–dependent manner (P <0.01). Compared with UVB-irradiated model group, the apoptosis rate of HaCaT cell in other groups was decreased by 6.94% and 3.68% respectively. Moreover, the photo-protective effect of green tea extracts was better than that of black tea extracts, which were consistent with the content of tea polyphenols and catechins their contained. Green and black tea extracts could relieve UVB-induced oxidative damage and apoptosis of HaCaT cells, which might be the reason that they raised the oxidase activity and cleared the oxy-radicals in cells. Moreover, the photo-protective effect of green tea extracts against oxidative damage and apoptosis of HaCaT cells from UVB irradiation was better than that of black tea extracts.