玉竹水溶性成分分离及其糖苷酶抑制活性

Separation of Water-soluble Constitituents in Polygonati Odorati Rhizoma and Their Glucosidase Inhibitory Activity

目的：研究玉竹中具有降血糖作用的生物碱成分并进行分离鉴定。方法：组合运用多种离子交换树脂色谱对玉竹水提物进行分离纯化,采用NMR和MS等光谱技术鉴定化合物结构;采用PNPG法和DNS法对所分离生物碱成分进行抗α-葡萄糖苷酶和抗α-淀粉酶活性筛选。结果：从玉竹水提物中分离得到8个化合物,其中2个多羟基生物碱,2个酰胺类化合物,3个氨基酸以及甜菜碱。其结构分别鉴定为1-deoxynojirimycin（1）,fagomine（2）,L-azetidine-2-carboxylic acid（3）,1,2（S）-pyrrolidinedicarboxamide（4）,（2S）-citrullinamide（5）,丝氨酸（6）,γ-氨基丁酸（7）和甜菜碱（8）。对化合物1,2,4,5,8分别进行了α-葡萄糖苷酶和α-淀粉酶抑制活性筛选。其中化合物1和2有显著的α-葡萄糖苷酶抑制活性,半数抑制浓度（IC50）分别为0.098,0.272 mol·m L-1,作用效果优于阳性药阿卡波糖（IC500.493 mol·m L-1）。此外,化合物1对α-淀粉酶有抑制活性,IC50为0.681 mol·m L-1,但抑制活性较阿卡波糖（IC500.035 mol·m L-1）弱。结论：化合物1~8均为首次从玉竹中分离得到。化合物1和2有显著的抗α-葡萄糖苷酶活性。因此,多羟基生物碱类成分是玉竹发挥降血糖作用的药效物质基础。

Objective： To study the polyhydroxylated alkaloids of Polygonati Odorati Rhizoma with hypoglycemic effect. Method： The water extract of Polygonati Odorati Rhizoma was isolated and purified by various ion-exchange resins chromatography. The structures of isolated compounds were identified by using spectral analysis such as NMR and MS. The inhibitory activities on α-glucosidase and α-amylase of the isolated alkaloids were screened by PNPG and DNS methods. Result： Eight compounds were obtained from the water extract of Polygonati Odorati Rhizoma,including two polyhydroxy alkaloids,two acylamides,three amino acids and betaine. These isolates were identified as 1-deoxynojirimycin（ 1）,fagomine（ 2）,L-azetidine-2-carboxylic acid（ 3）,1,2（ S）-pyrrolidinedicarboxamide（ 4）,（ 2S）-citrullinamide（ 5）,serine（ 6）,-aminobutyric acid（ 7） and betaine（ 8）.Compounds 1,2,4,5 and 8 were evaluated for their inhibitory activity on α-glucosidase and α-amylase.Compounds 1 and 2 showed potent inhibitory effect on α-glucosidase,with IC50 of 0. 098,0. 272 mol·m L- 1,respectively,whose activities were superior to the positive control Acarbose（ IC50 of 0. 493 mol·m L- 1）.Furthermore,compound 1 showed inhibitory effect on α-amylase（ IC50 of 0. 681 mol·m L- 1）,but its inhibitoryactivity was inferior to Acarbose（ IC50 of 0. 035 mol·m L- 1）. Conclusion： Compounds 1-8 were isolated from this plant for the first time,and compounds 1 and 2 showed significant inhibitory effect on α-glucosidase. Therefore,polyhydroxylated alkaloids are the active components of Polygonati Odorati Rhizoma for exerting hypoglycemic effect.