Small Molecule Compounds Based On The Two Keto Acid Structure In The Design, Synthesis And Anti Hcv Active Research

The RNA-dependent RNA polymerase (RdRp) of Hepatitis C Virus, also known as protein NS5B, is a key enzyme for the replication of virus and has been recognized as a promising and validated target for HCV therapies.The recent progress in development of NS5B inhibitors was reviewed in chapter1. Phenyl diketoacids (DKA) are the inhibitors which bind to the active sites of NS5B, and have the potential advantages to decrease the side effects and drug resistance induced by viral mutations. However, due to their poor physicochemical properties, many DKA analogues or mimics with NS5B inhibitory activities have been designed and prepared to improve the druggabilities and cell-based antiviral activities, which are significant for the studies of structure-activity-relationship and mechanism of this class of inhibitors and for the discovery of new anti-HCV chemical therapies.In chapter2, a common feature-based pharmacophore model, established by DKA analogues or mimics with NS5B inhibitory activities reported in the literatures, was used as a filtrating tool to screening our in-house natural product database, followed by further screening via NS5B structural-based docking. A total of31hits identified in silico were screened cell-based anti-HCV assay. Finally, two naturally occurring flavones luteolin and apigenin were indentified with potent anti-HCV activities, and three compounds, classified as isoflavone, chalcone and anthraquinone, were also demonstrated moderate potencies. Moreover, luteolin was also showed good NS5B inhibition effect in the enzyme-based assay.In chapter3, the leading compound luteolin was modified and optimized based on the SARs of the flavonoid derivatives.46Derivatives of luteolin, which modified at3-position,7-position and B ring, were designed, synthesized and their anti-HCV activities and cytotoxicity were evaluated. Among the newly synthesized congeners, some compounds possess the similar antiviral activities with the leading compound luteolin, and the preliminary SARs of this series derivatives were also summarized, which could guide the subsequent work of structural modification in the future. In chapter4, with the aim of expanding the structural diversity of this class of anti-HCV agents,39compounds, which classified as aryl diketo tetrazole, aryl diketo triazole,4-quinolone-3-carboxylic acid and coumarin, were designed by the application of bioisosteres and scaffold hopping strategies from the leading compounds phenyl diketoacid and flavonoids derivatives. These compounds were then synthesized and their anti-HCV activities and cytotoxicity were evaluated. Among these newly synthesized congeners, pyridin-2-yl diketotetrazole was proved to possess similar anti-HCV activities with luteolin, and its lower molecular weight leads to higher ligand efficiency. So this compound could act as excellent leading compound in the future structural modification work.In chapter5, the NS5B protein was expressed and purified in E. coli system. It’s RdRp activity was detected by gel-based assay, in which radio-labeled RNAs are visualized following gel electrophoresis. This work could support the establishment of NS5B inhibitors assay system.