含脱氧葡萄糖结构的芳基C-葡萄糖苷类钠-葡萄糖共转运子2(SGLT2)抑制剂的构效关系研究

Type 2 diabetes is now the increasing concern throughout the world. Sodium-glucose co-transporter 2 (SGLT2) is a novel target for type 2 diabetes with completely different mechanism of action from the current targets. SGLT2 is located in the S3 segment of the renal proximal tubule,and is responsible for the re-absorption of the glucose that is filtered by the renal glomerulus back to the blood. Thus, SGLT2 inhibitors can inhibit the SGLT2 activity to decrease the re-absorption of the glucose, thus lowering the blood glucose. The most advanced SGLT2 inhibitor, dapagliflozin, was approved in 2012 in Europe Union. The SGLT2 inhibitors are characterized by lack of structural diversity, as justified by the fact that the structures of both the launched and the investigational SGLT2 inhibitors in later clinical trials are aryl C-glycosides, particularly C-glucosides. So it is extremely urgent and important to discover new SGLT2 inhibitors with novel structures. Based on our excellent earlier results in this field, we herein aim to study the structure-activity relationship (SAR) of the deoxyglucose-bearing aryl C-glucosides as SGLT2 inhibitors. In the earlier studies, we discovered that the 6-deoxylated dapagliflozin (D-6) is a more potent SGLT2 inhibitor, whose IC50 against SGLT2 is 0.67 nM as compared with dapagliflozin itself (1.1 nM) and could induce more urinary glucose in vivo in the animal model of urinary glucose excretion (UGE). D-6 is almost the most potent SGLT2 inhitors discovered so far. So it is very promising to systematically investigate the SAR of the deoxylated dapagliflozin at all the hydroxyl groups in the glucose moiety as well as all the other investigational SGLT2 inhibitors so that a general rule can be created. First, using dapagliflozin as the template, we will carry out the systematic deletion of each of the hydroxyl groups in the glucose moiety in dapagliflozin. The 4 deoxylated derivatives thus obtained will be subjected to both in vitro (IC50 against SGLT2 and SGLT1, and selectivity: IC50[SGLT1]/IC50[SGLT2]) and in vivo assay (UGE: Urinary Glucose Excretion and OGTT: Oral Glucose Tolerance Test). Subsequently, the deoxy pattern that is found to be promising as proved by the evaluations described above will be expanded to other SGLT2 inhibitors that are now studied in later clinical trials, such as canagliflzoin, ipragliflozin, empagliflozin, tofogliflozin, luseogliflozin and ertugliflozin, to test its generality. The main objective of this study is to discover and clarify the SAR of the deoxy aryl C-glucosides as SGLT2 inhibitors, as well as to discover a new SGLT2 inhibitor with novel structure which is of preliminary druggability.

钠-葡萄糖共转运体2(Sodium-Glucose Co-transporter 2, SGLT2)抑制剂通过抑制SGLT2的活性来减少原尿中葡萄糖被重吸收回血液中从而达到降低血糖的目的，其中dapagliflzoin已于2012年在欧盟上市。该类抑制剂的结构特征单一，现有上市和在研的全是芳基C-糖苷。破解这种结构的单一性成为该领域亟需解决的课题。本研究拟在良好的前期研究基础上，首先以dapagliflozin为模板，对芳基C-葡萄糖苷结构中葡萄糖片段内的羟基进行系统的脱氧研究，对所有的单脱氧衍生物进行靶点(IC50:SGLT2)、选择性(IC50:SGLT1/SGLT2)和在体药效(UGE和OGTT)研究，而后将由此发现的具有良好成药性的脱氧规律拓展到其他在研的SGLT2抑制剂来进一步验证这个规律。本研究的目标是发现葡萄糖脱氧对活性影响的普遍规律，力争发现一个具备良好成药前景的候选药物。

根据项目计划书的进度要求，本研究首先完成了dapagliflozin分子中葡萄糖环上四个OH单脱氧的系统研究，通过体外对人SGLT2/SGLT1的抑制和大鼠口服糖耐量(OGTT)实验以及尿糖排泄(UGE)排泄实验，获得了D-6和D-3两个活性优异的SGLT2抑制剂，并得到了四个OH的构效关系(SAR)：dapagliflozin分子中葡萄糖环上2-OH对于维持SGLT2抑制剂活性是必需的，4-OH也比较重要，而4-OH和6-OH则不是必需的，而且6-OH脱除后会使活性显著提高。而后通过3,6-二脱氧和3,6-脱水两条途径对3-OH和6-OH同时脱氧进行了进一步的研究，补充了上述SAR：葡萄糖环上至少需要3个OH对于维持dapagliflozin的SGLT2抑制剂的活性是必需的。将上述SAR中的3-OH和6-OH单脱氧在dapagliflozin、canagliflozin、ipragliflozin和empagliflozin等代表性SGLT2抑制剂上进行了验证，得到了较为完善的普遍性规律：“6-OH不是SGLT2抑制剂分子中维持SGLT2抑制活性的必需基团”的结论具有一定的普遍性；但是3-OH脱去后对活性的影响则与母体分子相关，有的没有影响(dapagliflozin)，而有的则会导致活性完全丧失(canagliflozin和empagliflozin)，似乎没有普遍规律。随后对dapagliflozin的3-OH位置进行了一系列的衍生化研究，发现将3-OH氧化为C=O的产物(即3-CO)的SGLT2抑制活性非常好。随后又完成了上述新发现的活性优异的SGLT2抑制剂的合成路线和晶型研究，为开发这些化合物打下了基础。在拓展研究中，本课题新发现的D-6 (泰格列净)完成了临床前评价，并获得了I期临床批件。综上，本课题顺利完成了项目计划书预设的研究任务；发表论文15篇，其中SCI收录7篇；申报专利4项；培养学生7人；泰格列净临床批件和专利成功以5500万转让。