香蕉皮抗氧化和抑制人肝癌HepG2细胞活性研究

对香蕉皮提取物（banana peel extraction，BPE）的体外抗氧化作用和抗肿瘤活性进行了研究。使用福林酚和硝酸铝法测定BPE中总多酚和总黄酮含量；通过检测DPPH和O₂^-自由基清除能力测定BPE的体外抗氧化活性；采用Alamar Blue法检测BPE对HepG2细胞活性的影响；荧光染色及流式技术检测HepG2细胞凋亡；免疫印迹技术检测凋亡蛋白的变化；Caspase活性检测试剂盒测定Caspase-3和Caspase-9的活性；Caspase-9和Caspase-3抑制剂验证BPE抗肿瘤相关的信号转导通路。结果表明，BPE中总多酚和总黄酮含量分别为39.23 ± 2.35 mg·L^-1和26.53 ± 1.97 mg·L^-1；BPE显示出一定的DPPH和O₂^-自由基清除能力（65.31%±3.82%和51.29%±4.23%），可明显抑制HepG2细胞的增殖（IC₅₀=54.32 mL·L^-1）；BPE通过上调Caspase-3、Bax、Bid、Apaf-1、Bak、p53、Caspase-9的表达，下调Bcl-2、Bcl-xl的表达诱导HepG2细胞凋亡；Caspase-9和Caspase-3抑制剂（Z-LEHD-FMK、Ac-DEVD-CHO）在一定程度上逆转了BPE的增殖抑制活性。BPE具有一定的自由基清除能力，对HepG2细胞具有明显增殖抑制作用，这些结果为香蕉皮的进一步开发利用提供了数据支撑。

Study on Antioxidant Activity and Inhibitory Effect of Banana Peel on HepG2 Cells

The invitro antioxidant and anticancer potential of banana peel extraction （BPE） against HepG2 cells was evaluated. Quantitative analysis for total phenolic and flavonoid content in BPE were determined by Folin-Ciocalteu and Al（NO₃）₃ colorimetric assay. The antioxidant activity of BPE in vitro was evaluated by measuring the scavenging capacity DPPH and O₂^- free radical. The anticancer effect of the BPE on HepG2 cells was investigated using Alamar Blue assay. The apoptosis of HepG2 cells was detected by fluorescence staining and flow cytometry. Western blot analysis was used to detect the changes of apoptotic proteins. Caspase activity kits were used to determine the activities of Caspase-3 and Caspase-9. The Caspase-9 and Caspase-3 specific inhibitors further validated the signal transduction pathway related to BPE anti-tumor. The total phenolic and flavonoid content in the BPE was 39.23±2.35 mg·L^-1 and 26.53±1.97 mg·L^-1， respectively. The BPE also demonstrated potent DPPH， O₂^- radical scavenging capacity （65.31%±3.82% and 51.29%±4.23%）. BPE significantly inhibited the proliferation of HepG2 cells with an IC₅₀ value of 54.32 mL·L^-1. BPE induced HepG2 apoptosis by up regulating the expression of Caspase-3， Bax， Bid， Apaf-1， Bak， p53 and Caspase-9， and down regulating the Bcl-2 and Bcl-xl. Furthermore， Caspase-9 and Caspase-3 specific inhibitor （Z-LEHD-FMK and Ac-DEVD-CHO） reverse the proliferation inhibitory activity of BPE in HepG2 cells. BPE has a certain free radical scavenging capacity， and has an obvious inhibitory effect on HepG2 cell proliferation， providing data support for further development and utilization of banana peel.