Design,Synthesis And Biological Evaluation Of Novel Pyrido[3,2-d]Imidazole Derivatives As Hepatitis B Virus Inhibitors

Hepatitis B virus (HBV), the prototype of the Hepadnaviridae family, is different from the general retroviral. HBV replicates through an RNA intermediate, and then integrate into the host genome. HBV is the most common cause of viral hepatitis B and other liver disease, which can be transmitted parenterally, sexually and perinatally. As World Health Organization (WHO) reported, there are2billion people infected with hepatitis B virus all around the world, and about4million people were chronically infected. Hepatitis B virus infection can cause acute hepatitis, fulminant hepatitis, chronic hepatitis, cirrhosis, liver decompensation, and carcinoma (HCC), and so on, which cause one million people died around the world every year. Therefore, the hepatitis B virus infection is still a severe world health problem.In scientist’s efforts from various countries, the effective first-generation and second-generation HBV vaccine have been developed (the third-generation HBV vaccine are being developed in the domestic), to prevent HBV infection effectively, but the HBV vaccines has no effect on the infected people and has some inadequacies. In addition, the current anti-HBV drugs, approved for marketing by FDA, are immunomodulatory agents (interferon-α and pegylated interferon-α-2α) and antiviral therapy (lamivudine, adefovir dipivoxil, entecavir, telbivudine, tenofovir, clevudine, and NOV-205), but interferon-α and pegylated interferon-α-2α has many disadvantages, such as poor tolerance, frequent subcutaneous administration, side effects, the high cost, and so on. Except NOV-205(listed in Russia) the small molecule non-nucleoside antiviral drug, the other six antiviral drugs with drug resistance and side effects (such as renal toxicity and myopathy) are all the nucleoside/nucleotide analogues which affect hepatitis B virus reverse transcriptase (RT). In addition, the current antiviral therapy can not completely remove covalently closed circular DNA (cccDNA), and can not completely clear the hepatitis B virus. In summary, it is crucial to research and develop safe, effective, low toxicity and anti-resistance non-nucleoside inhibitors.Years of research found that the benzimidazole ring is an aromatic heterocyclic nucleus with important biological activity, and its derivatives possess a variety of anti-viral activity. So far, many benzimidazole derivatives can effectively inhibit replication of HBV, and anti-HBV activity of benzimidazole derivatives provided us an important study direction of the non-nucleoside hepatitis B virus inhibitors.According to the bioisosterism and the benzimidazole derivatives as lead compounds with anti-HBV activity, the structures of benzimidazole ring were modified by introducting N atoms at different positions in the benzene ring, and finally designed a series of pyrido[3,2-d]imidazole derivatives as HBV inhibitors. The purpose of this modification is expected to retain the compound’s good anti-HBV activity and increase the oral bioavailability and water solubility of target compounds, and ultimately improve the efficacy of the treatment of HBV infection of the target compounds. A series of pyrido[3,2-d]imidazole derivatives that its substituents selected from the substituents of benzimidazole HBV inhibitors with a good anti-HBV activity were designed though the design ideas and synthesized, and evaluated as HBV inhibitors.First,2-chloro-3-nitro pyridine, the raw material, reacted with the substituted amines the electrophilic substitution reaction in reflux. Second, the nitro of generated intermediate was reduced to amino-group by H2in the Pd/C as catalyst, and then, the received product and substituted carboxylic acid which are synthesized by ourselves reacted condenssed reaction to get amide compounds under DCC. Finally, the amide compounds generate the pyrido[3,2-d]imidazole derivatives in the acetic acid as catalyst. The final new20target compounds were synthesized and their structures were identified by IR,1H NMR and MS.ELISA and MTT methods were used to detect the inhibition of HBsAg, HBeAg, and cytotoxicity in HepG2.2.15cells which is human hepatitis B virus transgenic hepatocellular carcinoma cells, respectively. The anti-HBV activity of the20non-nucleoside pyrido[3,2-d]imidazole derivatives were evaluated in vitro. Most of the compounds showed good activity of inhibition of HBsAg and HBeAg secretion which were better than the control drug (lamivudine and adefovir dipivoxi), but cytotoxicity were also higher than the control drug. The compounds QQ1-10, QQ1-11, QQ1-12and QQ1-15inhibit HBeAg secretion with an IC50below10uM; compounds QQ1-16, QQ1-17, QQ1-18, and QQ1-20inhibit HBeAg secretion with an IC50in the range of40to800μM; the anti-HBeAg activity of the compounds QQ1-1, QQ1-5, QQ1-10, QQ1-11, QQ1-12, QQ1-17, QQ1-19, and QQ1-20were in the range of10-20μM; the anti-HBsAg activity of the compounds QQ1-2, QQ1-3, QQ1-7, QQ1-13, QQ1-15, QQ1-16, and QQ1-18were in the range of20-40μM. Especially, the compounds QQ1-10, QQ1-11, QQ1-12all showed wonderful activity of inhibition of HBsAg and HBeAg secretion. The same time, the SAR of the compounds were analyzed in this paper, and had some significance for further research in the future.In this article, we take the bioisosterism and the benzimidazole derivatives as lead compounds which have anti-HBV activity, and a series of20new pyrido[3,2-d]imidazole compounds were designed, synthesized and evaluated as HBV inhibitors. The results showed that some compounds had good anti-HBV activity, which are of great important significance for non-nucleoside anti-HBV drug development in the future.