Design,Synthesis And Activity Evaluation Of Novel Fused Heterocycles As Urate Transporter 1(URAT1) Inhibitors

Gout is a metabolic disease caused by purine metabolism disorder,the most important biochemical basis of it is hyperuricemia.With the improvement of people’s living standards,the prevalence of hyperuricemia and gout in the world has been rising over the past few years.At present,the drugs used for the treatment of gout are very limited and mainly rely on xanthine oxidase inhibitors(XOI)and uricosuric drug.However,these drugs have some drawbacks,such as poor efficacy and side effects.Therefore,there is an urgent need to develop novel,efficient and safe anti-gout drugs.The main pathogenesis of hyperuricemia and gout is increased uric acid production or impaired renal excretion,and 90%of gout is caused by insufficient renal excretion.Many uric acid transporters have been reported for uric acid reabsorption and secretion with further research of chemical biology and proteomics.Urate transporter 1(URAT1)is the most significant transporter,which controls more than 90%of uric acid reabsorption after glomerular filtration.By inhibiting URAT1,the reabsorption of uric acid can be reduced,and the excretion of uric acid can be enhanced,which can lower the level of serum uric acid in the body and reduce the possibility of gout attacks.Since URAT1 contains 12 transmembrane domains,the molecular structure is highly complex,and the three-dimensional structure of its protein has not been resolved,so it is impossible to carry out rational target-based drug design.In this thesis,we analyzed the structures of URAT1 inhibitors reported in recent articles and patents and summarized the structure-activity relationships(SARs).Two series of novel URAT1 inhibitors were designed and synthesized using a ligand-based drug design strategy.Initially,we carried out preliminary studies and obtained the lead compound Ⅱ-3a.Further,we designed a novel series of acyl sulfonamide derivatives(Series Ⅰ)through modifying the thioacetic acid side chain using the bioisosterism strategy.Moreover,by combining the drug design strategies(molecular hybridization and scaffold hopping),we spliced the pyridine thioglycolic acid side chain containing anionic groups with the rigid skeleton of aromatic heterocycles containing carbonyl groups.Based on this,the second series of compounds with tetrahydroisoquinoline(Series ⅡA)and benzomorpholine(Series ⅡB)derivatives were synthesized.From the tested Series Ⅰ,most of the compounds displayed prominent in vitro URAT1 inhibitory activity,comparable to the positive drug(Lesinurad).Among all of the compounds,16(IC50=7.68±0.47 μM),110(IC50=7.56±0.52 μM),I14(IC50=7.31 ±0.62 μM)and I15(IC50=7.90±0.47μM)were found to be more active than Lesinurad(IC50=9.38±0.79 μM).From the target activity results of Series Ⅰ,it was noticed that it also has an inhibitory effect on another uric acid transporter,glucose transporter 9(GLUT9).Compound 110 exhibited potent activity with the IC50 value of 55.96±10.38 μM.Additionally,in vivo uric acid lowering experiments were performed for the most active four compounds and the results revealed that all the compounds could reduce the serum uric acid level in mice.The decrease rate of 110 was 73.29%,which is significantly higher than that of Lesinurad(26.89%),presumably due to its dual inhibitory activity of URAT1 and GLUT9.Subsequent tests showed that I10 has good physicochemical properties and low acute toxicity in mice.All the compounds from Series ⅡA and Series ⅡB displayed noticeable URAT1 inhibitory activity,and most of them were comparable to Lesinurad.ⅡA-s4(IC50=9.82±2.27 μM)and ⅡB-s2(IC50=0.09±1.97 μM)exhibited relatively good inhibitory activity(Lesinurad IC50=8.44±2.21 μM).In addition,we preferably selected 6 carboxylic acids and their corresponding esters(12 compounds in total)to evaluate the uric acid-lowering activity in mice.The results reveal that the compounds with acid or ester groups have similar activity,and ⅡA-s4(52.90%)and ⅡB-s4(40.93%)display better activity than Lesinurad(28.80%).In conclusion,two series of novel fused heterocycles as URAT1 inhibitors were designed and synthesized using ligand-based drug design method,bioisosterism,molecular hybridization and scaffold hopping strategies.Several lead compounds were identified with significant activity through in vitro URAT1-inhibitory activity screening and in vivo uric acid lowering test in mice.From both in vitro and in vivo experiments,110 is identified as the most potent lead compound,worthy of further research and development.