芒果苷体内代谢及代谢产物结构与抑制PCSK9活性关系研究

Protein convertase subtilisin/kexin type 9 (PCSK9) has been one of the hottest targets on the hyperlipidemia and atherosclerosis treatment throughout the world, recently. However, the PCSK9 inhibitors on market are only monoclonal antibodies with quite localized treatment, and no listed small molecular of PCSK9 inhibitors could be obtained. . According to our previous discovery, some mangiferin metabolites, isolated from the urine in rats after oral administration of mangiferin, displayed significant inhibition on the key protein of atherosclerosis - PCSK9 and lipid synthesis transcription factor - SREBP-1c, but not for the parent drug - mangiferin. Furthermore, the synthetic derivatives on the basis of the structure templates of mangiferin metabolites exhibited more potential than that of mangiferin metabolites, indicating of the presence of structure - activity relationship. . Thus, our application would focus on the generated mechanism of mangiferin metabolites in vivo, the accumulation and synthesis of mangiferin metabolites, the synthetic derivatives of mangiferin metabolites, and the relationship between the structure of synthetic derivatives and PCSK9 inhibition, etc., in order to illustrate the structure-activity relationship between the mangiferin metabolites as well as its synthetic derivatives and PCSK9 inhibition. The above research would provide scientific basis for the further development of PCSK9 inhibitors.

前蛋白转换酶枯草溶菌素9(PCSK9)是近年国际上治疗高血脂和动脉粥样硬化的的热门靶点，但目前针对PCSK9靶点上市的药物均为单克隆抗体，治疗存在局限性，尚未见小分子药物上市。. 我们发现大鼠口服芒果苷后从尿中富集的部分代谢产物对动脉粥样硬化的关键蛋白PCSK9和脂质合成重要转录因子SREBP-1c有显著抑制作用，而芒果苷原形无该活性。同时，以芒果苷代谢物为结构模板，人工合成的部分代谢物衍生物的活性强于代谢产物，显示出一定的构效关系。. 本申请将对芒果苷的体内代谢产物生成机制 、代谢物的富集及合成制备、代谢物结构修饰衍生物的人工合成、代谢产物及衍生物结构与抑制PCSK9活性的关系等方面进行深入系统研究，阐明代谢物及结构修饰衍生物与活性的构效关系，为芒果苷结构类型的PCSK9蛋白抑制剂研发提供科学依据。

通过分析鉴定不同模型动物口服的芒果苷后生物样品的代谢物，发现芒果苷在的代谢途径为：去糖基化，甲基化，糖基化，去羟基化，葡萄糖醛酸化，硫酸酯化。相比与正常大鼠检测到23个代谢物，在糖尿病和肠道菌抑制大鼠体内分别检测到44和6个代谢物，这与疾病导致大鼠肠内转运体(MDR)和代谢酶(COMT, UGT, SULT)的mRNA水平改变有关。通过药动学实验，发现抑制CYP450酶、UGT酶、P-gp转运体和肠道菌并不能提高芒果苷生物利用度；芒果苷可在肠道菌的作用代谢生成芒果苷元，但暴露量极低。.从大鼠灌胃芒果苷后的尿液和粪中富集分离出5个代谢产物，人工合成制备出17个芒果苷代谢物衍生物。结合药效筛选，分别有11和5个化合物可分别抑制SREBP1-c 和PCSK9基因表达水平。归纳构效关系，发现口山酮骨架上羟基的数目和取代位置可以通过形成分子内氢键改变对PCSK9抑制活性。 .体外药效筛选表明，芒果苷元比芒果苷具有更强的降糖降脂活性。体内代谢和药动实验表明，芒果苷元发生葡萄糖醛酸化、硫酸酯化、甲基化及糖基化等广泛代谢，其生物利用度高达30.4%，远高于芒果苷（1.2%），这与芒果苷元良好的膜渗透性和非P-gp转运体的底物相关。因此，芒果苷元具有更好的药物先导化合物潜质。