摘要随着人们生活水平不断提高，大量污染物质无节制排放，水体富营养化事件频频发生。藻类在新陈代谢过程中会不断向周围环境释放有害藻毒素。节球藻毒素（nodularin; NOD）是其中的一类具有强烈肝毒性的新型环境生物毒素，大量研究表明NOD可以促进机体氧化应激作用。本实验采用模式生物ICR小鼠作为实验对象，采用10μg/kg的NOD进行体内暴露，以小鼠肝脏作为主要的研究对象。结果显示在暴露21d之后，NOD可诱导小鼠产生显著地氧化应激作用。结果显示各类抗氧化酶活性降低：（1）谷胱甘肽（GSH）含量降低了23%；（2）谷胱甘肽S-转移酶（GST）活力降为对照组的0。88倍；（3）谷胱甘肽还原酶（GR）的活性降为原来的0。56倍；（4）谷胱甘肽过氧化物酶（GPx）活力降低了29%；（5）与此同时，在NOD暴露后，小鼠肝脏内脂质过氧化产物丙二醛（MDA）与对照组相比增加了2。11倍，活性氧（ROS）也显著上升。上述变化充分表明：节球藻毒素可以对小鼠肝脏抗氧化系统产生威胁。71964

表没食子儿茶素没食子酸酯（EGCG）是中国绿茶中主要的茶多酚活性成分，目前的药用价值已得到了国内外研究人员的广泛认可。先前的大量研究表明EGCG具有显著的抗氧化功能。本研究采用50μg/kg、100μg/kg、200μg/kg的EGCG对小鼠肝脏进行预处理，研究EGCG在10μg/kg的NOD暴露下，对小鼠肝脏抗氧化系统的保护效用。本实验的EGCG未显示对小鼠肝脏抗氧化系统的毒性或其他明显的作用。结果显示：（1）与NOD暴露组相比，EGCG可有效提高小鼠肝脏细胞GSH含量，并呈现一定的浓度依赖关系；（2）200μg/kg的EGCG预处理组的GST活力上升为纯NOD处理组的1。15倍；（3）GR活力提高了21%；（4）高浓度保护组GPx含量为纯NOD暴露组的4。36倍；（5）200μg/kg的EGCG预处理组的脂质过氧化产物MDA含量显著降低（72%），ROS水平最终趋于与对照组一致。综上所述，EGCG可以有效抑制NOD引起的氧化应激作用，对小鼠肝脏抗氧化系统起到关键的保护作用。

Abstract As people's living standards continue to improve, a large number of uncontrolled emission of pollutants come into environment, accordingly, eutrophication occurs frequently。 During its metabolic process, algae will continue to release harmful algal toxins into the surrounding environment。 Nodularin (nodularin; NOD) is one of a new class of biological toxins with a strong liver toxicity, a large number of studies have shown that NOD promotes oxidative stress effect。 In this study, a model organism --ICR mice were used as experimental subjects。 We used 10μg / kg of NOD in vivo exposure, designing mouse liver as the main object of study。 The results showed that after exposure of 21d, NOD can induce significant oxidative stress in mice。 The results showed that all types of antioxidant enzyme activity decreased: (1) glutathione (GSH) decreased by 23%; (2) glutathione S- transferase (GST) viability dropped 0。88 times comparing with the control group; ( 3) glutathione reductase (GR) activity dropped to 0。56 times comparing with the original; (4) the activity of glutathione peroxidase (GPx) was reduced by 29%; (5) At the same time, after NOD exposure, mice hepatic lipid peroxidation product malondialdehyde (MDA) compared with the control group increased by 2。11 times, reactive oxygen species (ROS) also increased significantly。 These changes fully demonstrated the following result: nodularin can pose a threat to the antioxidant system in liver of mice。

Epigallocatechin gallate (EGCG) is a main active ingredient in Chinese green tea polyphenols, the current medicinal value has been widely recognized by domestic and foreign researchers。 Previous studies have shown that a large number of EGCG has significant antioxidant function。 In this study, 50μg / kg, 100μg / kg, 200μg / kg of EGCG pretreated the liver of mice。 We studied protection of EGCG to the utility system at 10μg / kg of NOD exposure on mouse liver anti-oxidation。 During this experiment, EGCG toxicity or other significant effects on liver antioxidant system are not shown。 The results showed that: (1) compared with exposure group of NOD, EGCG can effectively improve the GSH content of liver cells in mice, and it also showed a certain concentration dependent manner; (2)  GST viability with 200μg / kg of EGCG pretreated rose to 1。15 times comparing with the group of pure NOD treatment; (3) GR activity increased by 21%; (4) GPx content with a high concentration of protected groups was 4。36 times as that in the  group of pure NOD exposed; (5) a significant reduction of lipid peroxidation products MDA content (72% ) with 200μg / kg of EGCG pretreated , ROS levels eventually become consistent。as the control group。  In summary, EGCG can inhibit oxidative stress-induced of NOD, playing a key protective role antioxidant system of mouse liver。