新型双位点CETP抑制剂的设计、合成及生物活性研究

Cholesterol ester transfer protein (CETP) plays a crucial role in the generation and development of atherosclerosis (AS) so that it has been considered as a key target for the prevention and treatment of hyperlipidemia and atherosclerosis. The phase 3 clinical study of Anacetrapib progresses smoothly. We have found that the nature active substance oleanolic acid (OA), which belongs to pentacyclic triterpenoid (PT), got certain CETP inhibitory activity. Besides, it got similar structure with CE scaffold, which is the nature substrate of CETP. And they occupied the same binding site, nearby the current known CETP inhibitors. Accordingly, we have proposed to find and merge active fragments to the PT scaffolds to occupy the two sites with the purpose to improve the inhibitory activity for this type of CETP inhibitors. The obtained target compound 24 (IC50: 2.3 μM) got significantly improved CETP inhibitory activity and favored hypolipidemic effect. The target compound UA-6 was more potent (IC50: 0.28 μM), preliminarily confirmed the rationality of our idea. Based on these, this project will continue the discovery of novel dual-site inhibitors with potent CETP inhibitory activity by further structure optimization and finding the favored fragments against the key amino acid residues. Meanwhile, the binding mode and mechanism will be explored and the lipid-regulating effect of the target compounds will be evaluated. This project will be a solid foundation for the discovery of novel CETP targeted PT hypolipidemic drugs.

胆固醇酯转运蛋白（CETP）在动脉粥样硬化（AS）的发生发展过程中扮演着至关重要的角色，因而被认为是防治高脂血症及AS的关键靶标。其抑制剂Anacetrapib三期临床研究进展顺利。我们发现五环三萜（PT）类化合物齐墩果酸具有一定的CETP抑制活性，与CETP天然底物胆固醇酯骨架结构相似，结合位点相同，与现有抑制剂的结合位点邻近。据此，我们提出基于PT类骨架结构拼合活性片段从而占据这两个位点来达到提高该类化合物活性的目的。前期已获得的目标化合物24（IC50：2.3 μM）活性大幅提高，降血脂效果较好，化合物UA-6更具潜力（IC50: 0.28 μM），初步确证了设计思路的合理性。在此基础上，本项目拟针对关键氨基酸残基，进一步优化结构并筛选优势片段，以期获得高活性的全新双位点CETP抑制剂，探究其结合模式和作用机制，评价其血脂调节功效，为新型CETP靶向性PT类降血脂药物的发现提供基础。

高血脂症诱发的动脉粥样硬化（AS）是心血管疾病发生发展的重要病理基础。胆固醇酯转运蛋白（CETP）是胆固醇逆转运过程中的关键蛋白，被认为是防治高血脂症和AS的关键靶标，因而CETP抑制剂的发现成为研究热点之一。我们发现五环三萜（PT）类化合物齐墩果酸具有一定的CETP抑制活性，结构与CETP天然底物胆固醇酯的骨架相似，结合位点相同，与现有CETP抑制剂的结合位点邻近。据此，我们提出基于PT类骨架结构拼合活性片段从而占据这两个位点来达到提高该类化合物活性的目的。因此，本项目根据该思路进行目标化合物的设计，化学合成，体外CETP抑制活性评价，以及体内降血脂活性评价。实验结果证明占据双位点的目标化合物具有较好的CETP抑制活性和体内血脂调节作用，确证了化合物设计思路的合理性。我们采用分子对接、分子动力学模拟等方法，发现该类化合物通过占据双位点与CETP稳定结合，并阐明了代表性化合物活性差异的原因，揭示了对活性具有重要影响的关键性氨基酸残基和受体配体相互作用。本研究为新型CETP靶向血脂调节药物的发现提供了基础。然而，鉴于目前四个已知CETP抑制剂失败或不好的III期临床研究结果，其应用前景有待商榷。