太白楤木皂苷的抗氧化作用研究

The antioxidative activity of saponin from Aralia taibaiensis

目的:探讨太白楤木皂苷的抗氧化作用,为进一步利用其防治疾病提供基础数据。方法:采用体外化学法检测太白楤木皂苷的总抗氧化能力。在细胞实验中,采用氧化剂叔丁基过氧化氢(tert-butyl hydroperoxide,tBHP)诱导细胞氧化损伤。设立相应对照组和药物保护组,给予太白楤木皂苷(5μg/mL)预处理保护,收集样品,流式细胞仪荧光法检测细胞活性氧(reactive oxygen species,ROS)水平,Western blot方法检测抗氧化转录因子核呼吸因子2(nuclear respiratory factor 2,Nrf2)及其下游的血红素加氧酶1(heme oxygenase-1,HO-1)和谷氨酸半胱氨酸连接酶(γ-glutamate-cysteine ligase,GCL)的表达水平。结果:太白楤木皂苷体外实验检测总抗氧化能力表现出明显的剂量-效应关系。在细胞实验中,tBHP可以显著提高细胞ROS水平,引起细胞的氧化损伤,太白楤木皂苷预处理可以显著降低tBHP诱导的细胞ROS水平。同时发现太白楤木皂苷可以显著拮抗tBHP引起Nrf2及其下游的HO-1、GCL的催化亚基(GCLC)和调节亚基(GCLM)表达水平的升高。结论:太白楤木皂苷在化学反应体系及细胞水平,均显现出了抗氧化作用,具有抗氧化防治疾病的应用前景。

The total antioxidant capacity of saponin was determined by ferric-reducing ability of plasma（FRAP） method. In the cellular study, tert-butyl hydroperoxide（tBHP） was employed as an oxidant to induce oxidative stress, and saponin （5μg/mL） was pre-incubated with the ceils 12 h before challenged by tBHP in the protective group. Then cellular ROS was labeled with DCFH-DA and determined by flow cytometry. The protein levels of nuclear respiratory factor 2 （Nrf2）, heme oxygenase-1 （HO-1）, γ-glutamate-cysteine ligase （GCL） were evaluated by Western blot. RESULTS： The saponin showed marked antioxidative effect, tBHP induced massive reactive oxygen species （ROS） production, for which saponin pre-treatment showed significant inhibition. Saponin pre-treatment also significantly inhibited the tBHP-stimulated protein expressions of Nrf2, HO-1 and GCL. CONCLUSION： Saponin from Aralia taibaiensis has potent antioxidative activity, indicating its potential clinical application in oxidative stress-related diseases. [KEY WORDS] Aralia taibaiensis; antioxidative; reactive oxygen species ; saponin; nuclear respiratory factor 2