壳寡糖的抗氧化及肝保护功能

Antioxidant and hepatoprotective activities of chitosan oligosaccharide

目的研究壳寡糖(COS)的抗氧化能力和对CCl4诱导的小鼠肝损伤的保护作用,并初步探讨其作用机制。方法雄性昆明种小鼠,腹腔注射CCl4(20 mg.kg-1)制造肝损伤模型,实验组提前连续12 d灌胃给予COS(1.5 g.kg-1)。小鼠经CCl4损伤24 h后,取血,分离得到血清,测定各组小鼠血清中丙氨酸转氨酶(ALT)和天门冬氨酸转氨酶(AST)的活性。脱颈处死小鼠,取部分肝组织,分别测定肝匀浆中总抗氧化能力(T-AOC)、总巯基(T-SH)和非蛋白结合巯基(NP-SH)含量、金属硫蛋白含量(MT)、丙二醛(MDA)含量和DNA损伤情况等指标。结果COS组与CCl4组相比,ALT、AST活性和MDA含量分别下降了62.2%、52.9%和34.3%。T-AOC和NP-SH含量分别提高了26.1%和16.3%。MT含量是空白对照组的2.15倍。但是没有抑制T-SH含量降低的作用。DNA电泳结果显示,COS组与CCl4组的DNA链都形成一系列1 kb大小左右的DNA片断。结论COS具有抗氧化能力,对CCl4诱导的小鼠肝损伤有较为明显的保护作用,但是不能减轻DNA的氧化性损伤。

Objective To investigate the protective effect of chitosan oligosaccharide（COS） on carbon tetrachloride（CCl4）-induced liver damage in male ICR mice and the possible mechanisms involved.Methods Liver damages of male ICR mice were produced by celiac injection with CCl4（20 mg·kg^-1）.Mice of experimental group were pretreated with COS（1.5 g·kg^-1） once daily for 12 consecutive days.Twenty-four hours after the administration of CCl4,blood was collected and serum was separated for determination of the activities of alanine aminotransferase（ALT） and aspartate aminotransferase（AST）.Then the animals were sacrificed by cervical decapitation,and their livers were dissected out.Total antioxidant capabilities（T-AOC）,sulfhydryl content,metallothionein（MT） and malondialdehyde（MDA） quantification in liver homogenate were measured and qualitative analysis of liver DNA fragmentation was carried out.Results Serum ALT and AST activities and MDA formation in COS pretreated group were decreased to 62.2%,52.9% and 34.3%,respectively,compared to those in CCl4 group.T-AOC and NP-SH contents were improved to 26.1% and 16.3%.Pretreatment with COS could significantly increase MT expression to 2.15 fold of the control.However,COS showed no effect on increasing the content of T-SH.DNA isolated from the COS group and the CCl4 group both showed the fragmentation about 1 kb via agarose gel electrophoresis.Conclusions The results indicate that pretreatment with COS could efficiently improve the antioxidant activity and protect mice against CCl4 induced liver damage,but genotoxicity could not be mitigated.