Studies on the Discovery of Novel Pyrimidine-Based Capsid Assembly Modulators as Potent Anti-HBV Agents

Abstract

To treat the chronic hepatitis B virus infection, the core assembly inhibitors have been developed. In this study, I synthesized the novel potent pyrimidine derivatives as core assembly inhibitors and their anti-viral effect was evaluated through the in-vitro and -vivo biological experiments. Structure and activity and property relationship of the 2,4,6-substituted pyrimidine derivatives were studied through the R1, R2, and R3 modifications. The results of modification at R1 position indicated that oxidation of the methylthio moiety enhanced the anti-HBV effect and in-vitro liver microsomal metabolic stability and aliphatic amino heterocycles (piperazine, N-piperidin-4-amine, and 1-piperidin-4-amine) at R2 position were improved the physicochemical properties such as solubility and cell permeability. Additionally, di-substitution with halides at the para- and meta-positions of the aniline group at R3 position dramatically improved metabolic stability. Interestingly, optimized derivatives presented a dramatic increase in the inhibitory effects (23a–23i), and efficacy of these compounds was comparable to positive compound GLS4. Among the synthesized derivatives, compound 23h (R1 = MeSO2, R2 = 1-piperidin-4-amine, R3 = 3-Cl-4-F-aniline) displayed potent inhibitory effects in the both in-vitro assays (52% inhibition in immunoblot analysis of HBV capsid assembly at 100 nM level and 181 nM of IC50 level in serum HBV DNA quantification by qPCR). The molecular docking study of compound 23h was carried out to predict the reasons for potent anti-HBV effects. Moreover, treatment with compound 23h for 5 weeks showed significantly decreased serum levels of HBV DNA levels (3.35 log reduction) in a human liver chimeric uPA/SCID mouse model and these effects were significantly increased when it was combined with traditional reverse transcriptase inhibitor, tenofovir, for HBV treatments.