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目的从青钱柳Cyclocarya paliurus叶中提取分离多糖,对其结构进行表征,并评价其α-葡萄糖苷酶抑制活性。方法采用水提醇沉法制备粗多糖,经732阳离子交换树脂脱蛋白,50%乙醇沉淀,得青钱柳叶多糖CP50。利用高效凝胶渗透色谱-十八角度激光光散射联用法(HPGPC-MALLS)测定CP50的相对分子质量,采用PMP柱前衍生-高效液相色谱法(HPLC)测定单糖组成。采用甲基化分析、傅里叶变换红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)对CP50的结构进行表征。采用PNPG法对CP50抑制α-葡萄糖苷酶活性进行评价。结果 CP50的相对分子质量为59 000,由半乳糖醛酸(GalA)、葡萄糖(Glc)、半乳糖(Gal)、阿拉伯糖(Ara)、甘露糖(Man)、木糖(Xyl)、鼠李糖(Rha)和葡萄糖醛酸(Glc A)8种单糖组成,摩尔比为29.1∶25.6∶16.5∶9.3∶6.7∶6.1∶4.1∶2.6,分子中主要含有→4)GalA(1→、→4)Glc(1→和→4)Gal(1→糖苷键,在半乳糖的C6位存在分支结构。CP50能显著抑制α-葡萄糖苷酶活性,半数抑制浓度(IC50)为3.3μg/m L,远小于抗2型糖尿病药物阿卡波糖(193.6μg/m L),属于混合非竞争性抑制。结论 CP50单糖种类多、结构复杂,属于果胶类酸性多糖,且具有较好的α-葡萄糖苷酶抑制活性,具有潜在的开发应用价值。
OBJECTIVE: To isolate polysaccharides from the leaves of Cyclocarya paliurus, characterize its structure and evaluate its α-glucosidase inhibitory activity. Methods Crude polysaccharides were prepared by water extraction and alcohol precipitation. The polysaccharides were deproteinized by 732 cation exchange resin and precipitated with 50% ethanol to obtain CP50. The relative molecular mass of CP50 was determined by high performance gel permeation chromatography (HPGPC-MALLS) and PMP pre-column derivatization-high performance liquid chromatography (HPLC). The structure of CP50 was characterized by methylation analysis, Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (1H-NMR). The inhibition of α-glucosidase activity by CP50 was evaluated by PNPG. Results The relative molecular mass of CP50 was 59 000. The relative molecular mass of CP50 was determined by the following method: GalA, Glc, Gal, Ara, Xyl, (Rha) and glucuronic acid (Glc A), the molar ratio is 29.1: 25.6: 16.5: 9.3: 6.7: 6.1: 4.1: 2.6, 4) Glc (1 → and → 4) Gal (1 → glycosidic bond, branched at the C6 position of galactose.CP50 can significantly inhibit the α-glucosidase activity, the IC50 was 3.3μg / m L , Which was far less than that of acarbose, an anti-type 2 diabetes drug (193.6 μg / mL), which was mixed and non-competitively inhibited.Conclusion CP50 monosaccharides have many types and complicated structures and belong to pectic acid polysaccharides with good α - glucosidase inhibitory activity, with potential development and application value.