复合全谷豆粗杂粮的活性成分及其对胆汁酸代谢的调控

目的分析比较复合全谷豆粗杂粮中膳食纤维(dietary fiber,DF)、抗性淀粉(resistant starch,RS)、总黄酮和总皂甙等活性成分,了解其对大鼠粪胆汁酸(fecalbile acid,FBA)排出的影响及其调控机制。方法按国家标准及文献方法测定复合全谷豆粗杂粮中DF、RS、总黄酮和总皂甙的含量。44只SPF级SD大鼠随机分为阴性对照组、高脂模型组、米面组和复合全谷豆粗杂粮组,分别给予相应饲料连续喂养8周。实验开始前和结束后,代谢笼收集大鼠粪便,磷钼酸法测定FBA。RT-PCR法测定大鼠肝脏组织中胆固醇7α-羟化酶(cholesterol 7α-hydroxylase,CYP7A1)mRNA和肝X受体α(Liver X receptorα,LXRα)mRNA的表达。结果复合全谷豆粗杂粮中每100g含DF 15.3g、RS 9.03g、总黄酮0.45g和总皂甙0.24g。复合全谷豆粗杂粮组大鼠FBA排出量显著升高(P<0.05);CYP7A1 mRNA和LXRαmRNA表达比其他3组显著增加(P<0.05)。结论复合全谷豆粗杂粮比面粉大米富含DF、RS、黄酮和皂甙等活性物质。可以促使胆汁酸合成经典途径中限速酶CYP7A1和其上游受体LXRαmRNA表达的上调,有效地增加大鼠FBA的排出量,起到改善脂代谢紊乱的作用。

Active constituents in compound whole grain and its regulation on bile acids metabolism

Objective To analyze and compare the contents of dietary fiber,resistant starch,flavonoid and total saponins in the compound whole grain,to observe the effects of compound whole grain on the excretion of bile acid and its regulation mechanisms.Methods The contents of dietary fiber,resistant starch,flavonoid and saponins in compound whole grain were determined according to the national standard methods and other methods in literatures.Forty-four SPF grade SD rats were allocated randomly into four groups:the negative control group,hyperlipemia model group,rice-flour group and compound whole grain group,and each group was provided with corresponding diet for 8 consecutive weeks.The excrements of rats were collected at the beginning and the ending of the experiment by using metabolic cages.The expression of CYP7A1 mRNA and LXRαmRNA were also observed.Results The composition of compound whole grain was dietary fiber 15.3g,resistant starch 9.03g,flavonoid 0.45g and saponins 0.24g per 100g.The excretion of bile acid was increased significantly(P<0.05),and the expression of CYP7A1 mRNA and LXRαmRNA was significantly higher in the compound whole grain group than the other three groups(P<0.05).Conclusion Compound whole grain is rich in DF,RS,flavonoid and saponins than common flour and rice.The expression of rate-limiting enzyme CYP7A1 mRNA in the classical pathway of bile acid synthesis and its upstream acceptor LXRα mRNA could be up-regulated by compound whole grain,thus effectively increasing bile acid excretions,and improving the disorders of lipid metabolism.