重庆沱茶提取物对2型糖尿病小鼠的改善作用

Improvement effects of Chongqing Tuo tea extract on mice with type 2 diabetic

【目的】探究重庆沱茶提取物对2型糖尿病(T2DM)小鼠的降血糖效果及其作用机制,为重庆沱茶保健功能研究和T2DM防治提供理论依据。【方法】利用热水浸提、真空冷冻干燥制备获得重庆沱茶提取物,采用福林酚法、蒽酮比色法、茚三酮比色法、高效液相色谱法(HPLC)等检测其主要品质成分。选取24只4周龄无特定病原体(SPF)级雄性C57BL/6J小鼠,6只用基础饲料喂养,设为正常对照组(NC组);18只采用高脂饲料喂养联合链脲佐菌素(STZ)注射诱导构建T2DM小鼠模型,以低剂量(400 mg/kg,TTEL组,6只)和高剂量(800 mg/kg,TTEH组,6只)重庆沱茶提取物灌胃,T2DM模型对照组(MC组,6只)和NC组以等量生理盐水灌胃,干预周期为8周,每天灌胃1次。试验期间测量记录小鼠体质量、摄食量和空腹血糖,干预结束后,分析重庆沱茶提取物对小鼠组织病理形态、血糖、血脂和肝脏氧化应激的影响。【结果】重庆沱茶提取物的主要品质成分中,茶多酚含量最高(34.45%),茶多酚主体成分(儿茶素类)中,表没食子儿茶素没食子酸酯(EGCG)含量最高(18.22%)。重庆沱茶提取物干预可有效缓解T2DM小鼠的体质量减轻和肝脏、胰腺病理损伤;干预8周后,TTEL组和TTEH组小鼠空腹血糖均较MC组显著下降(P<0.05,下同),TTEL组降幅为23.95%,TTEH组降幅为48.94%。同时,重庆沱茶提取物能改善T2DM小鼠的葡萄糖耐受能力和胰岛素敏感性,其中高剂量重庆沱茶提取物的改善效果更佳;与MC组相比,TTEL组、TTEH组小鼠的血清甘油三酯(TG)、总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)含量均显著降低,高密度脂蛋白胆固醇(HDL-C)含量显著增加,表明重庆沱茶提取物干预可显著改善脂代谢紊乱;与MC组相比,TTEL组、TTEH组小鼠肝脏丙二醛(MDA)含量均显著降低,肝脏超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)活性均显著提高,表明重庆沱茶提取物干预能显著改善肝脏氧化应激损伤。【结论】重庆沱茶提取物具有降血糖效果,具备开发为降血糖功能食品的潜力。

【Objective】To explore the hypoglycemic effect and mechanism of Chongqing Tuo tea extract on mice with type 2 diabetic(T2DM),and to provide theoretical basis for the study of health care function of Chongqing Tuo tea and the prevention and treatment of T2DM.【Method】Chongqing Tuo tea extract was prepared by hot water extraction and vacuum freeze-drying.The main quality components were detected by Folin-Ciocalteu method,anthrone colorimetry method,ninhydrin colorimetry method and high performance liquid chromatography(HPLC).Twenty-four four-week-old specific pathogen-free(SPF)male C57BL/6J mice were selected as the research objects.Among them,6 mice were fed with basic diet as normal control group(NC group),18 mice were fed with high-fat diet,and then combined with streptozotocin(STZ)injection to induce T2DM mouse model.The low-dose(400 mg/kg,TTEL group,6 mice)and high-dose(800 mg/kg,TTEH group,6 mice)of Chongqing Tuo tea extract were given by gavage,and the T2DM model control group(MC group,6 mice)and NC group were given the same amount of normal saline by gavage.The intervention period was 8 weeks,once a day.During the experiment,the body weight,food intake and fasting blood glucose of the mice were measured and recorded.After the intervention,the effects on histopathological morphology,blood glucose,blood lipid and liver oxidative stress of the mice were analyzed.【Result】Among the main quality components of Chongqing Tuo tea extract,the content of tea polyphenols was the highest(34.45%).Among the main components of tea polyphenols(catechins),the content of epigallocatechin gallate(EGCG)was the highest(18.22%).The intervention of Chongqing Tuo tea extract could effectively alleviate the weight loss and pathological damage of liver and pancreas in T2DM mice.After 8 weeks of intervention,fasting blood glucose significantly decreased in the TTEL and TTEH groups compared with the MC group(P<0.05,the same below),the decreases were 23.95%in the TTEL group and 48.94%in the TTEH group.The extract of Chongqing Tuo tea could improve the glucose tolerance and insulin sensitivity of T2DM mice,among which the improvement effect of high dose of Chongqing Tuo tea extract was better.Compared with the MC group,the levels of serum triglyceride(TG),total cholesterol(TC),low density lipoprotein cholesterol(LDL-C)in TTEL group and TTEH group were significantly decreased,and the content of high density lipoprotein cholesterol(HDLC)was significantly increased,indicating that the intervention of Chongqing Tuo tea extract could significantly improve the disorder of lipid metabolism.Compared with the MC group,the content of malondialdehyde(MDA)in liver of mice in TTEL group and TTEH group was significantly decreased,and the activities of superoxide dismutase(SOD),catalase(CAT)and glutathione peroxidase(GSH-Px)in liver were significantly increased,indicating that the intervention of Chongqing Tuo tea extract could significantly improve liver oxidative stress injury.【Conclusion】Chongqing Tuo tea extract has hypoglycemic effect and has the potential to be developed as a hypoglycemic functional food.