食药用真菌中羊毛甾烷型三萜抑制α-葡萄糖苷酶的构效关系及其降血糖药效研究

Diabetes endangers the public health severely. α-Glucosidase inhibitors (AGIs) are an important category of drugs for diabetes treatment. However, the clinical AGIs are all glucose analogs, and mostly they cause gastrointestinal adverse reaction to impede a long-term medication. Novel types of AGIs which are efficient and suitable for a long-term usage are in great need. Previously, the applicant found lanostane-type triterpenoids from Ganoderma lucidum showed significant inhibitory effect on α-glucosidase in vitro. Lanostane-type triterpenoids were also rich in Inonotus obliquus and Ganoderma applanatum by UPLC-DAD-Q/TOF-MS technology and they showed strong inhibition against α-glucosidase. It is indicated that lanostane-type triterpenoids are potent anti-hyperglycemic constituents in edible and medicinal fungi sources. In this project, the two medicinal fungi full of lanostane-type triterpenoids will be extracted in large scale. Lanostane-type triterpenoids will be systematically isolated and identified, and their inhibition against α-glucosidase will be evaluated. The anti-hyperglycemic effect of bioactive triterpenoids will also be studied in Caco-2 cells and in diabetic mice. This project will reveal the structure-activity relationship of anti-α-glucosidase lanostane-type triterpenoids. It is hoped that one or two anti-α-glucosidase lead compounds will be found from edible and medicinal fungi, which will provide scientific foundation for developing novel AGIs.

糖尿病严重危害人类健康，α-葡萄糖苷酶抑制剂是治疗糖尿病的一类重要药物，然而现有药物的化学结构均为葡萄糖类似物，且易引起胃肠道损伤等不良反应致使无法长期用药。因此寻找不同化学类型、高效且适合长期服用的α-葡萄糖苷酶抑制剂具有重要意义。申请人拟在前期发现食药用真菌赤芝中羊毛甾烷型三萜可抑制α-葡萄糖苷酶活性，降低糖尿病小鼠餐后血糖水平，以及采用UPLC-DAD-Q/TOF-MS检识和α-葡萄糖苷酶活性筛选策略发现桦褐孔菌和树舌灵芝两株食药用真菌中含有丰富的羊毛甾烷型三萜并显示抑制α-葡萄糖苷酶活性的基础上，扩大两株活性真菌的提取规模，对羊毛甾烷型三萜化合物进行系统分离、活性评价、作用机制和体内药效的研究。本项目将揭示羊毛甾烷型三萜抑制α-葡萄糖苷酶活性的构效关系，发现1-2个效果显著的抑制α-葡萄糖苷酶先导化合物，为新型高效可长期服用的α-葡萄糖苷酶抑制剂类药物开发奠定科学基础。

糖尿病严重危害人类健康，α-葡萄糖苷酶抑制剂是治疗糖尿病的一类重要药物，然而现有药物的化学结构均为葡萄糖类似物，且易引起胃肠道损伤等不良反应致使无法长期用药。因此寻找不同化学类型、高效且适合长期服用的α-葡萄糖苷酶抑制剂具有重要意义。申请人前期发现食药用真菌羊毛甾烷型三萜可抑制α-葡萄糖苷酶活性，降低糖尿病小鼠餐后血糖水平。基于前期基础，本项目完成了桦褐孔菌三萜富集活性部位的分离纯化和结构鉴定，所得三萜化合物的α-葡萄糖苷酶抑制活性评价、酶抑制动力学研究、分子对接、分子动力学模拟和体内对糖脂代谢的调节作用。从活性部位分离得到46个三萜类化合物，12个为新化合物，1个为新天然产物。Inonotusol F (24) 和betulic acid (27) 的活性最强，分别为11.5 ± 0.4和13.1 ± 0.7 M。3D-QSAR分析显示在 C-2、C-26、C-27、C-28 或 C-31 处引入取代基可其活性。Inonotusol F (24) 和betulic acid (27)是α-葡萄糖苷酶的非竞争抑制剂，与α-葡萄糖苷酶具有高亲和力。Inonotusol F (24) 和betulic acid (27)与 α-葡萄糖苷酶的结合主要是Van de Walls作用，活性口袋的PHE298、GLU302、PRO307、TRY311和ASP404是inonotusol F与α-葡萄糖苷酶结合区域的关键氨基酸残基，而PHE155、PHE175、HIE277、PHE298、GLU302、TRY311 和 ASP347则betulic acid与-葡萄糖苷酶结合的关键氨基酸残基。Betulic acid可降低正常小鼠餐后血糖水平的急剧波动，长期给药可通过改变肠道菌群的组成和丰度，调节db/db小鼠糖脂代谢紊乱的状态。研究成果丰富了对食药用菌三萜的化学认识，揭示羊毛甾烷型三萜抑制α-葡萄糖苷酶活性的构效关系，发现效果显著的抑制α-葡萄糖苷酶先导化合物，为新型高效可长期服用的α-葡萄糖苷酶抑制剂类药物开发奠定科学基础。