Design and synthesis of aminothiazole based Hepatitis B Virus (HBV) capsid inhibitors

Thiazole-Based IL-17 Inhibitors Discovered by Scaffold Morphing

The pro-inflammatory cytokine interleukin-17A (IL-17) plays an important role in the body's defense against bacterial and fungal infections. However, overexpression of IL-17 has been associated with several diseases, including rheumatoid arthritis, asthma, psoriasis, and even cancer. The role of IL-17 in psoriasis has been confirmed by clinical use of IL-17 antibodies, e. g. secukinumab (Cosentyx®). Ongoing research is focused on discovering low molecular weight IL-17 inhibitors. In this publication, we present thiazole-based IL-17 inhibitors discovered through a scaffold-morphing strategy. This strategy involved ring-opening of a known scaffold and utilization of a chalcogen interaction between thiazole-sulfur and central amide-oxygen to maintain the coplanar conformation found in the parent compound. The new scaffold enabled the generation of highly potent compounds with good overall profile. The optimized compounds 11 and 15 demonstrated good exposure in rats after oral dosing. Importantly, compound 11 exhibited no adverse effects in a rat tolerability study after a four-day administration of up to 300 mg/kg/day.

Development of benzimidazole-based compounds as novel capsid assembly modulators for the treatment of HBV infection

Hepatitis B virus (HBV) capsid assembly modulators (CAMs) represent a promising therapeutic approach for the treatment of HBV infection. In this study, the hit compound CDI (IC50 = 2.46 ± 0.33 μM) was identified by screening of an in-house compound library. And then novel potent benzimidazole derivatives were designed and synthesized as core assembly modulators, and their antiviral effects were evaluated in vitro and in vivo biological experiments. The results indicated that compound 26f displayed the most optimized modulator of HBV capsid assembly (IC50 = 0.51 ± 0.20 μM, EC50 = 2.24 ± 0.43 μM, CC50 = 84.29 μM) and high selectivity index. Moreover, treatment with compound 26f for 14 days significantly decreased serum levels of HBV DNA levels in the Hydrodynamic-Injection (HDI) mouse model. Therefore, compound 26f could be considered as a promising candidate drug for further development of novel HBV CAMs with the desired potency and safety.

Targeting the Virus Capsid as a Tool to Fight RNA Viruses

Several strategies have been developed to fight viral infections, not only in humans but also in animals and plants. Some of them are based on the development of efficient vaccines, to target the virus by developed antibodies, others focus on finding antiviral compounds with activities that inhibit selected virus replication steps. Currently, there is an increasing number of antiviral drugs on the market; however, some have unpleasant side effects, are toxic to cells, or the viruses quickly develop resistance to them. As the current situation shows, the combination of multiple antiviral strategies or the combination of the use of various compounds within one strategy is very important. The most desirable are combinations of drugs that inhibit different steps in the virus life cycle. This is an important issue especially for RNA viruses, which replicate their genomes using error-prone RNA polymerases and rapidly develop mutants resistant to applied antiviral compounds. Here, we focus on compounds targeting viral structural capsid proteins, thereby inhibiting virus assembly or disassembly, virus binding to cellular receptors, or acting by inhibiting other virus replication mechanisms. This review is an update of existing papers on a similar topic, by focusing on the most recent advances in the rapidly evolving research of compounds targeting capsid proteins of RNA viruses.

Discovery of novel HBV capsid assembly modulators by structure-based virtual screening and bioassays

HBV capsid assembly has been regarded as an attractive potential target for anti-HBV therapy. In this study, we discovery the Novel HBV capsid assembly modulators (CAMs) through structure-based virtual screening and bioassays. A total of 16 structurally diverse compounds were purchased and assayed, including three compounds with inhibition rate > 50% at 20 μM. Further lead optimization based on the most potent compound II-1-7 (EC₅₀ = 5.6 ± 0.1 µM) were performed by using substructure searching strategy, resulting in compound II-2-9 with an EC₅₀ value of 1.8 ± 0.6 μM. In bimolecular fluorescence complementation (BiFC) assay, compound II-2-9 inhibited the HBV by disrupting the HBV capsid interactions. In summary, this study provides a highly efficient way to discover novel CAMs, and 2-aryl-4-quinolyl amide derivatives could serve as the starting point for development of novel anti-HBV drugs.

Synthesis of 4-oxotetrahydropyrimidine-1(2H)-carboxamides derivatives as capsid assembly modulators of hepatitis B virus

We report herein the synthesis and evaluation of phenyl ureas derived from 4-oxotetrahydropyrimidine as novel capsid assembly modulators of hepatitis B virus (HBV). Among the derivatives, compound 27 (58031) and several analogs showed an activity of submicromolar EC₅₀ against HBV and low cytotoxicities (>50 μM). Structure–activity relationship studies revealed a tolerance for an additional group at position 5 of 4-oxotetrahydropyrimidine. The mechanism study indicates that compound 27 (58031) is a type II core protein allosteric modulator (CpAMs), which induces core protein dimers to assemble empty capsids with fast electrophoresis mobility in native agarose gel. These compounds may thus serve as leads for future developments of novel antivirals against HBV.

Synthesis and evaluation of new phenyl acrylamide derivatives as potent non-nucleoside anti-HBV agents

As a continuation of our previous work, a series of new phenyl acrylamide derivatives (4Aa-g, 4Ba-t, 5 and 6a-c) were designed and synthesized as non-nucleoside anti-HBV agents. Among them, compound 4Bs could potently inhibit HBV DNA replication in wild-type and lamivudine (3TC)/entecavir resistant HBV mutant strains with IC₅₀ values of 0.19 and 0.18 μM, respectively. Notably, the selective index value of 4Bs was above 526, indicating the favorable safety profile. Interestingly, unlike nucleoside analogue 3TC, 4Bs could significantly inhibit 3.5 kb pgRNA expression. Molecular docking study revealed that 4Bs could fit well into the dimer-dimer interface of HBV core protein by hydrophobic, π-π and H-bond interactions. Considering the potent anti-HBV activity, low toxicity and diverse anti-HBV mechanism from that of nucleoside anti-HBV agent 3TC, compound 4Bs might be a promising lead to develop novel non-nucleoside anti-HBV therapeutic agents, and warranted further investigation.

Discovery of novel quinazolinone derivatives as potential anti-HBV and anti-HCC agents

As a continuation of earlier works, a series of novel quinazolinone derivatives (5a-s) were synthesized and evaluated for their in vitro anti-HBV and anti-hepatocellular carcinoma cell (HCC) activities. Among them, compounds 5j and 5k exhibited most potent inhibitory effect on HBV DNA replication in both drug sensitive and resistant (lamivudine and entecavir) HBV strains. Interestingly, besides the anti-HBV effect, compound 5k could significantly inhibit the proliferation of HepG2, HUH7 and SK- cells, with IC₅₀ values of 5.44, 6.42 and 6.75 μM, respectively, indicating its potential anti-HCC activity. Notably, the in vitro anti-HCC activity of 5k were more potent than that of positive control 5-fluorouracil and sorafenib. Further studies revealed that compound 5k could induce HepG2 cells apoptosis by dose-dependently upregulating Bad and Bax expression and decreasing Bcl-2 and Bcl-xl protein level. Considering the potent anti-HBV and anti-HCC effect, compound 5k might be a promising lead to develop novel therapeutic agents towards HBV infection and HBV-induced HCC.

Design, diversity-oriented synthesis and biological evaluation of novel heterocycle derivatives as non-nucleoside HBV capsid protein inhibitors

The capsid assembly is a significant phase for the hepatitis B virus (HBV) lifespan and is an essential target for anti-HBV drug discovery and development. Herein, we used scaffold hopping, bioisosterism, and pharmacophore hybrid-based strategies to design and synthesize six series of various heterocycle derivatives (pyrazole, thiazole, pyrazine, pyrimidine, and pyridine) and screened for in vitro anti-HBV non-nucleoside activity. Drug candidate NZ-4 and AT-130 were used as lead compounds. Several compounds exhibited prominent anti-HBV activity compared to lead compound NZ-4 and positive drug Lamivudine, especially compound II-8b, showed the most prominent anti-HBV DNA replication activity (IC₅₀ = 2.2 ± 1.1 μM). Also compounds IV-8e and VII-5b showed the best in vitro anti-HBsAg secretion (IC₅₀ = 3.8 ± 0.7 μM, CC₅₀ > 100 μM) and anti-HBeAg secretion (IC₅₀ = 9.7 ± 2.8 μM, CC₅₀ > 100 μM) respectively. Besides, II-8b can interact HBV capsid protein with good affinity constants (K_D = 60.0 μM), which is equivalent to lead compound NZ-4 ((K_D = 50.6 μM). The preliminary structure-activity relationships (SARs) of the newly synthesized compounds were summarized, which may help researchers to discover more potent anti-HBV agents.