新型抗痛风化合物3,5,2',4'-四羟基查尔酮对嘌呤代谢相关酶活性及尿酸转运体的影响

Gout occurs as a result of increased uric acid production, impaired renal uric acid excretion, or a combination of these mechanisms. The drugs for treatment of gout include xanthine oxidase inhibitors, of which allopurinol is the most often prescribed. Inhibitors of renal urate reabsorption such as benzbromarone are also employed as hypouricemic agents. However, these existing antihyperuricemic agents possess some undesirable effects such as hypersensitivity toward allopurinol. However, drugs available for treatment of gout patients with hyperuricemia are still limited. Therefore, there is an obvious need for novel agents or therapeutic strategies that could act on the physiological regulation of uric acid levels and prevention of uric acid-related diseases. .In our previous study, we found that 3,5,2',4'-tetrahydroxychalcone (P40) exhibited a significant inhibitory activity on xanthine oxidase with the mode of competiveness in vitro. In vivo, intragastric administration of P40 was able to significantly reduce serum urate levels in hyperuricemic mice, although the hypouricemic action was slightly less than that of allopurinol. Acute toxicity study showed that the maximum tolerated dose of P40 by intragastric administration in mice was more than 5.0 g/kg body weight. But the mechanisms of hypouricemic effects of P40 are still unclear. In present study, we will study the effects of P40 on PRPS、HGPRT、PRPPAT、XOD、URAT1 and GLUT9 in order to explore the possible mechanisms in molecular or cellular level and make a feasibility evaluation of novel drugs for the treatment of hyperuricemia and gout.

痛风是嘌呤代谢紊乱和（或）尿酸排泄减少所引起的一组代谢性、高发性疾病，但目前治疗药物非常有限。本课题组首次发现3,5,2',4'-四羟基查尔酮（P40）具有降低高尿酸血症小鼠尿酸水平的作用，其作用稍弱于等摩尔的别嘌醇，但毒性却远小于别嘌醇(LD50为0.7 g/kg)，P40小鼠灌胃给药的最大耐受量大于 5 g/kg，显示出高效低毒的特点(已获得国家发明专利)。但其降尿酸的作用机制尚不明确，前期研究发现对XOD有抑制作用，但是否与最新发现的肾脏尿酸转运体及嘌呤代谢的关键酶有关尚不清楚。该课题将研究P40降尿酸作用的药效、量效和时效关系以及对PRPS、HGPRT、PRPPAT、XOD和URAT1、GLUT9的影响，从动物、分子和细胞水平探讨其可能的作用机制，以期能够为将其研发成为治疗高尿酸血症和痛风的新型药物做出可行性评价。

高尿酸血症不仅是痛风最重要的生化基础，而且与代谢紊乱综合征密切相关，已成为威胁人类健康的严重的代谢性疾病。降低血尿酸水平是治疗痛风、预防痛风复发的重要措施，控制尿酸水平对于防治痛风的发生发展具有重要意义。然而，目前治疗药物却非常有限。本课题组首次发现3,5,2',4'-四羟基查尔酮（P40）具有降低高尿酸血症小鼠尿酸水平的作用，其作用稍弱于等摩尔的别嘌醇，但毒性却远小于别嘌醇(LD50为0.7 g/kg)，P40小鼠灌胃给药的最大耐受量大于 5 g/kg，显示出高效低毒的特点。该课题将以P40位研究对象，系统研究P40降尿酸作用的药效、量效和时效关系以及对PRPS、HGPRT、PRPPAT、XOD和URAT1、GLUT9的影响，探讨其可能的作用机制，以期能够为将其研发成为治疗高尿酸血症和痛风的新型药物做出可行性评价。   .本课题研究结果表明，（1）P40对正常小鼠的血尿酸水平和肝尿酸含量没有影响。（2）P40能显著降低氧嗪酸钾、次黄嘌呤、尿酸诱导的高尿酸血症小鼠尿酸水平，疗效与等摩尔的别嘌醇相当或略低，起效时间稍晚于别嘌醇。（3）P40能抑制尿酸生成关键酶XOD/XDH的活性，从而抑制尿酸的生成而降低尿酸。（4）体外研究表明，P40对嘌呤代谢中的其它关键酶---嘌呤核苷酸磷酸化酶（PNP）没有影响，也不影响PC12细胞的黄嘌呤-鸟嘌呤磷酸核糖转移酶（HGPRT）、磷酸核糖焦磷酸合成酶（PRPS）、磷酸核糖焦磷酸酰胺转移酶(PRPPAT) mRNA的表达。体内研究表明P40对氧嗪酸钾诱导的高尿酸血症小鼠脑的HGPRT、肝脏的PRPS和PRPPAT的mRNA的表达也没影响，但能降低次黄嘌呤诱导的高尿酸血症小鼠肝脏PRPS、PRPPAT的mRNA的表达和含量，其原因可能与造模剂不同有关，还有待进一步证实。（5）P40能降低尿酸诱导的高尿酸血症小鼠尿酸水平和提高大鼠尿酸排泄分数，初步表明有促进尿酸排泄的作用，其机制与下调GLUT9蛋白表达有关。