青稞麸皮提取物抑制α-葡萄糖苷酶活性研究及成分分析

研究青稞麸皮的正己烷、乙酸乙酯和甲醇提取物对α-葡萄糖苷酶的抑制活性。结果表明,3种不同极性的提取物均显示抑制效果,其中正己烷提取物和乙酸乙酯提取物的抑制活性强于市售α-葡萄糖苷酶抑制剂——阿卡波糖。进一步采用气相色谱-质谱联用法对正己烷提取物中脂肪酸、不皂化物、甾醇进行定性定量分析。正己烷提取物中的脂肪酸主要为亚油酸、油酸、棕榈酸、α-亚麻酸,占总脂肪酸的96.5%,这几种脂肪酸被证实对α-葡萄糖苷酶具有混合型抑制的活性。从不皂化物中分离得65个质谱峰,鉴定出甾醇类、三萜类、高分子脂肪醇等生物活性成分。同时对已鉴定的几种主要游离甾醇进行含量分析,结果显示β-谷甾醇和菜油甾醇为主要甾醇,两者共占总游离甾醇的83%,提取物中的甾醇、三萜类对α-葡萄糖苷酶抑制活性可能有一定贡献。由此可见,青稞麸皮是筛选α-葡萄糖苷酶抑制剂的优质天然资源。

Anti-α-Glucosidase Activities and Bioactive Components of Tibetan Hull-Less Barley Bran Extracts

The hexane, ethyl acetate and methanol extracts of Tibetan hull-less barley (THB) bran displayed dose-dependent inhibitory activities on α-glucosidase in vitro. The hexane and ethyl acetate extracts had higher inhibitory activities than did acarbose, which is used in clinical treatment of type 2 diabetes. Gas chromatography-mass spectrometry (GC-MS) analysis showed that linoleic acid, oleic acid, palmitic acid and α-linoleic acid were the main fatty acids in the hexane extracts, accounting for 96.5% of the total fatty acids. All of these four fatty acids have been reported to be potent inhibitors of α-glucosidase. Moreover, 65 peaks were separated from the unsaponifiable fractions, with 17 of them identified as sterols, triterpenes and long chain fatty alcohols, respectively. The total free phtosterol content was 7 357.72 mg/kg, which presented β-sitosterol, campesterol, desmosterol, stigmasterol, and fucosterol as the primary phytosterols. In addition, β-sitosterol and campesterol accounted for 83% of the total phtosterols. These results show that THB can be a natural source of potent α-glucosidase inhibitors.