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目的:研究荞麦壳黄酮提取物(buckwheat hull extracts,BHEs)对2型糖尿病大鼠血糖水平改善作用和机制。方法:体外实验中,测定了BHEs抑制α-葡萄糖苷酶和α-淀粉酶活性,并采用Lineweaver-Burk作图法确定其抑制反应的类型。体内实验中,高脂饮食与注射链脲佐菌素(streptozocin,STZ)复合诱导制备2型糖尿病大鼠模型,分为正常组(未诱导,蒸馏水),模型组(诱导,蒸馏水),阳性对照组(盐酸二甲双胍,100 mg/(kg·d))和BHEs低、中、高剂量组(50、100、200 mg/(kg·d),分别标记为LBHEs、MBHEs、HBHEs)。灌胃给药,每天1次,连续干预28 d,观察大鼠体质量、空腹血糖(fasting blood glucose,FBG)、空腹胰岛素(fasting serum insulin,FINS)和C肽水平变化,并进行口服糖耐量实验(oral glucose tolerance test,OGTT)。结果:BHEs在α-葡萄糖苷酶-麦芽糖体系中与其抑制活性成剂量依赖关系,当BHEs质量浓度为1 mg/m L时抑制率为41.12%,酶促动力学数据表明其为竞争型抑制。STZ诱导的2型糖尿病大鼠实验结果显示,与正常组相比,模型组大鼠体质量减少了33.1%,FBG升高到(17.85±2.25)mmol/L,而FINS、C肽水平分别降低了24.80%和12.77%(P<0.05);与模型组相比,BHEs实验组改善糖尿病大鼠体质量减少,且干预28 d后MBHEs组和HBHEs组大鼠FBG与干预前比较分别降低了39.4%和48.2%(P<0.05),OGTT曲线下面积降低了47.36%、59.47%(P<0.05),MBHEs组和HBHEs组同时改善大鼠血清FINS和C肽水平,与模型组相比分别提高了32.79%、34.44%和7.40%、13.08%(P<0.05)。结论:BHEs抑制α-葡萄糖苷酶活性和修复胰岛细胞功能的双重机制改善STZ诱导的2型糖尿病大鼠的血糖指标,并呈现一定的剂量-效应关系。
Objective: To investigate the effect and mechanism of buckwheat hull extracts (BHEs) on blood glucose level in type 2 diabetic rats. METHODS: BHEs were tested for their inhibitory activity on α-glucosidase and α-amylase in vitro. The type of inhibition was determined by Lineweaver-Burk mapping. In vivo, model of type 2 diabetes mellitus was induced by a combination of high fat diet and streptozocin injection (STZ). The rats were divided into normal group (untreated, distilled water), model group (induced, distilled water) (Metformin hydrochloride, 100 mg / (kg · d)) and BHEs low, medium and high dose groups (50, 100 and 200 mg / (kg · d), labeled as LBHEs, MBHEs and HBHEs). The rats were given intragastrically once a day for 28 days. The body weight, fasting blood glucose (FBG), fasting serum insulin (FINS) and C-peptide levels in rats were observed and their oral glucose tolerance Oral glucose tolerance test (OGTT). Results: The inhibitory activity of BHEs in a-glucosidase-maltose system was dose-dependent. The inhibitory rate of BHEs was 41.12% when the mass concentration of BHEs was 1 mg / ml, and the enzymatic kinetic data showed that BHEs were competitively inhibited. Compared with normal group, the body mass of model rats decreased by 33.1% and FBG increased to (17.85 ± 2.25) mmol / L, while the levels of FINS and C-peptide decreased in STZ-induced type 2 diabetic rats Compared with the model group, the BHEs experimental group reduced the body weight of diabetic rats, and the FBG of the MBHEs group and the HBHEs group decreased by 39.4 % And 48.2% (P <0.05). The area under the curve of OGTT decreased by 47.36% and 59.47% (P <0.05). The levels of FINS and C peptide in serum of MBHEs and HBHEs groups were also improved 32.79%, 34.44% and 7.40%, 13.08% respectively (P <0.05). CONCLUSION: The dual mechanism of BHEs inhibition of α-glucosidase activity and repair of islet cell function can improve the blood glucose level of STZ-induced type 2 diabetic rats and show a dose-response relationship.