桑叶降糖有效部位活性成分研究

Active constituents of hypoglycemic part from Morus alba L.

目的对桑叶中降糖活性部位进行化学成分研究。方法利用体外α-糖苷酶活性测定和小鼠高血糖模型筛选降糖活性部位。氨基酸分析仪分析氨基酸组成及含量,利用纤维素、离子交换等色谱柱进行分离纯化,通过NMR、MS等波谱分析手段鉴定化合物结构。结果桑叶中降糖活性成分主要集中在总碱部位,从中鉴定出15种氨基酸并测定了各种氨基酸含量;此外还分离得到8个化合物,除了以前报道过的DNJ(6)、fagomine(7)、1,4-dideoxy-1,4-imino-D-arabinitol(8)外,其余的分别鉴定为2-methyl-hydrazinecarboxylic acid(1)、zarzissine(2)、N-脒基脯氨酸(3)、去甲莨菪碱(1α,2β,3α,4β-tetrahydroxy-nor-tropane)(4)、grateloupinamide(5)。结论桑叶总碱部位为主要降糖活性成分,并且首次通过氨基酸分析鉴定桑叶总碱中氨基酸的种类和含量,分离出5个生物碱类成分,其中化合物1、2、3为首次从该属植物中分离得到,化合物3为新的天然产物。

Objective To determine the active chemical constituents of hypoglycemic parts from Morus alba L.. Methods The active hyperglycemic parts were screened by α-glycosidase enzyme activity in vitro and hypoglyeemic mouse model. Compositions and contents of amino acid were determined by amino acid analysis, separated and purified on cellulose and ion exchange. The structures were elucidated by NMR and MS. Results The active hypoglycemic parts were confirmed as alkaloids. A total of 15 amino acids were identified and determined from Morus alba L.. Eight compounds were isolated from alkaloids and deduced as 2-methyl-hydrazinecarboxylic acid （1）, zarzissine （2）, N-amidinoproline （3）, 1α, 2β, 3α, 4β-tetrahydroxy-nor-tropane （4） and grateloupinamide （5）, in addition to DNJ （6）, fagomine （7） and 1, 4-dideoxy-1, 4-imino-D-arabinitol （8）. Conclusion The active constituents from Morus alba L. are mainly alkaloids. The compositions and contents of amino acids in Morus alba L. have been identified for the first time by amino acid analysis, among which compound 3 is a brand new natural product and compound 1, 2 and 3 are firstly isolated from the same genus.