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（GlcA）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3.3 μg/mL，远小于抗2型糖尿病药物阿卡波糖（193.6 μg/mL），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 extract and isolate polysaccharide from Cyclocarya paliurus leaves, characterize its structural features and study its α-glucosidase inhibitory effect. Methods C. paliurus polysaccharide (CP50) was isolated and purified by water extraction and ethanol precipitation, deproteinization with 732 cation exchange resin and 50% ethanol precipitation. Molecular weight of CP50 was determined by high performance gel permeation chromatography-multiple angle laser light scattering (HPGPC-MALLS), and monosaccharide composition was analyzed by HPLC with PMP (1-phenyl-3-methyl-5-pyrazolone) pre-column derivatization. The structure of CP50 was characterized by methylation, Fourier transform infrared spectroscopy (FT-IR), and proton nuclear magnetic resonance spectrum (¹H-NMR), respectively. The α-glucosidase inhibitory effect of CP50 was investigated by PNPG method. Results The molecular weight of CP50 was 59 000. It contained eight kinds of monosaccharides including galacturonic acid, glucose, galactose, arabinose, mannose, xylose, rhamnose, and glucuronic acid with molar ratio of 29.1:25.6:16.5:9.3:6.7:6.1:4.1:2.6. CP50 was mainly composed of →4) GalA (1→, →4) Glc (1→ and →4) Gal (1→ with branches at C-6 position of galactose. Furthermore, our results showed that CP50 exhibited a potent inhibitory effect on α-glucosidase, and the value of IC₅₀ was determined to be 3.3 μg/mL which was much lower than the anti-type 2 diabetes drug acarbose (193.6 μg/mL). The inhibitory mode belongs to the mixed noncompetitive inhibition. Conclusion CP50 is a pectin-like acidic polysaccharide with complex structure. Moreover, CP50 possesses better α-glucosidase inhibitory effect and potential value for the drug development and utilization.

国家自然科学基金资助项目（31670811）；山东省科技重大专项（2015ZDJS04002）；山东省泰山学者工程专项；山东省重点实验室联盟项目资助