中文摘要：

目的：观察中波紫外线（UVB）辐射引起的人表皮角质形成细胞株HacaT细胞凋亡、细胞周期及p16、c-myc蛋白水平的影响及传统中药黄芩苷（baicalin）对它的干预作用.方法：以200 mg/L黄芩苷预处理HacaT细胞,以流式细胞仪检测经0、30、60和90 mJ/cm2的UVB照射后24 h细胞周期和凋亡率变化;以Western blot方法检测90 mJ/cm2 UVB照射后p16、c-myc 蛋白的表达水平.结果：UVB照射可诱导HaCaT细胞产生凋亡,凋亡率呈剂量依赖性增加;30 mJ/cm2 剂量下细胞可出现明显S期阻滞,随UVB剂量增大,S期细胞数量相对下降;照光后p16、c-myc蛋白水平均有所增高.加入黄芩苷处理可抑制UVB引起的上述变化.结论：黄芩苷可明显抑制UVB引起的凋亡与细胞周期阻滞以及p16、c-myc蛋白表达,证实该药具有有效的光保护作用.

英文摘要：

Objective：To evaluate the effects of UVB irradiation and intervention of baicalin on apoptosis, cell cycle, and expres- sion levels of p16 and c-myc protein in human eternal keratinocyte-HaCaT cells. Methods： Subconfluent HaCaT cells were irradi- ated with different dosages of UVB and treated with baicalin. The cell cycle and apoptotic rate were determined with a DNA flow cy- tometer 24 h after 0, 30, 60 and 90 mJ/cm2 UVB irradiation. Western blot assay was used to measure protein expression levels of p16 and c-myc after 30 mJ/cm2 UVB irradiation. Results：UVB-induced apoptosis of HaCaT cells increased with a manner of dependence on the irradiated dosages（0, 30, 60, 90 mJ/cm2） ;and S-phase arrest of the cell cycle under 30 mJ/cm2 of UVB irradiation were observed, but with the increasing of UVB dosage , the cell number in S-phase decreased. The levels of P16 and c-myc protein expression in the UVB group was higher than that in the control group （P〈0.05）. Pre-treatment of baicalin inhibited the above changes induced by UVB irradiation. Conclusions：Baicalin could inhibit apoptosis, cell cycle arrest and protein expression of p16 and c-myc induced by UVB, which shows the photo-protective effect of baicalin.