采用MTT法、Comet assay（彗星实验）和流式细胞分析法研究了表没食子儿茶素没食子酸酯（EGCG）对卡莫司汀引起的张氏肝细胞DNA损伤的保护作用及其机制。结果表明：EGCG能阻止卡莫司汀所致张氏肝细胞的生长抑制,卡莫司汀单用对张氏肝细胞的IC₅₀为43.31 μg/ml,当用无毒浓度25 μg/ml和50 μg/ml的EGCG与卡莫司汀联用时,对张氏肝细胞的IC₅₀分别提高至52.46 μg/ml和46.65 μg/ml。彗星分析结果表明EGCG还能减小卡莫司汀引起的张氏肝细胞DNA损伤,彗星Olive尾矩值由单用时的9.07±5.48降为联用时的6.02±2.46。EGCG还能减小卡莫司汀所致张氏肝细胞的早期凋亡率,25 μg/ml的EGCG和20 μg/ml的卡莫司汀联合处理4、6 h和24 h时,早期凋亡率分别从4.53±0.64（%）、6.01±0.14（%）、2.27±0.32（%）降至3.04±0.47（%）、5.61±0.10（%）、1.14±0.23（%）。说明EGCG能保护卡莫司汀对正常肝细胞的杀伤,其机理是它能减少这类药物引起的细胞DNA损伤,降低卡莫司汀所致细胞早期凋亡。

The protective effect and mechanism of (-)-epigallocatechin gallate (EGCG) combined with carmustine on the DNA damage of Chang liver cells were evaluated by MTT assay, flow cytometric assay and Comet assay respectively. The results showed that EGCG can prevent the growth inhibition caused by carmustine, the 50% inhibitory concentration (IC₅₀) of carmustine to Chang liver cells was 43.31 μg/ml, while it is combined with EGCG(25 μg/ml and 50 μg/ml, the concentration under which EGCG has no growth inhibition to Chang liver cells), the IC₅₀ to Chang liver cells increased to 52.46 μg/ml and 46.65 μg/ml respectively. EGCG also decreased carmustine-induced DNA damage in Chang liver cells according to Comet assay results. The Olive tail moment decreased from 9.07±5.48 to 6.02±2.46. EGCG also decreased the apoptosis percentages of Chang liver cells caused by carmustine. After Chang liver cells treated with EGCG(25 μg/ml) and carmustine (20 μg/ml) for 4 h, 6 h and 24 h, the apoptosis percentage decrease from 4.53±0.64（%）、6.01±0.14（%）、2.27±0.32（%）to 3.04±0.47（%）、5.61±0.10（%）、1.14±0.23（%）respectively. These results suggest that EGCG can protect the human normal liver cells from the lethal action by carmustine. The mechanism is the EGCG possess the activity of decreasing the DNA damage caused by these agents and the apoptosis percentage caused by carmustine.