Hepatitis B virus infection affects over 250 million chronic carriers, causing more than 800,000 deaths annually, although a safe and effective vaccine is available. Currently used antiviral agents, pegylated interferon and nucleos(t)ide analogues, have major drawbacks and fail to completely eradicate the virus from infected cells. Thus, achieving a “functional cure” of the infection remains a real challenge. Recent findings concerning the viral replication cycle have led to development of novel therapeutic approaches including viral entry inhibitors, epigenetic control of cccDNA, immune modulators, RNA interference techniques, ribonuclease H inhibitors, and capsid assembly modulators. Promising preclinical results have been obtained, and the leading molecules under development have entered clinical evaluation. This review summarizes the key steps of the HBV life cycle, examines the currently approved anti-HBV drugs, and analyzes novel HBV treatment regimens.

Metalloenzymes are central to the regulation of a wide range of essential viral and parasitic functions, including protein degradation, nucleic acid modification, and many others. Given the impact of infectious diseases on human health, inhibiting metalloenzymes offers an attractive approach to disease therapy. Metal-chelating agents have been expansively studied as antivirals and antiparasitics, resulting in important classes of metal-dependent enzyme inhibitors. This review provides the recent advances in targeting the metalloenzymes of viruses and parasites that impose a significant burden on global public health, including influenza A and B, hepatitis B and C, and human immunodeficiency viruses as well as Trypanosoma brucei and Trypanosoma cruzi.

Hepatitis B virus (HBV) remains a global health threat. Ribonuclease H (RNase H), part of the virus polymerase protein, cleaves the pgRNA template during viral genome replication. Inhibition of RNase H activity prevents (+) DNA strand synthesis and results in the accumulation of non-functional genomes, terminating the viral replication cycle. RNase H, though promising, remains an under-explored drug target against HBV. We previously reported the identification of a series of N-hydroxypyridinedione (HPD) imines that effectively inhibit the HBV RNase H. In our effort to further explore the HPD scaffold, we designed, synthesized, and evaluated 18 novel HPD oximes, as well as 4 structurally related minoxidil derivatives and 2 barbituric acid counterparts. The new analogs were docked on the RNase H active site and all proved able to coordinate the two Mg²⁺ ions in the catalytic site. All of the new HPDs effectively inhibited the viral replication in cell assays exhibiting EC₅₀ values in the low μM range (1.1–7.7 μM) with low cytotoxicity, resulting in selectivity indexes (SI) of up to 92, one of the highest reported to date among HBV RNase H inhibitors. Our findings expand the structure–activity relationships on the HPD scaffold, facilitating the development of even more potent anti-HBV agents.

Hepatitis B Virus (HBV) continues to pose a significant global health challenge, with over 254 million chronic infections and current therapies being non-curative, necessitating lifelong treatment. The HBV ribonuclease H (RNase H) is essential during HBV reverse transcription by cleaving the viral pregenomic RNA after it has been copied into the (−) polarity DNA strand, enabling the viral polymerase to synthesize the (+) DNA strand. Although RNase H inhibition terminates viral replication and thus viral infectiveness, its targeting as an HBV treatment is unexploited. Its catalytic site contains four carboxylates that bind to two Mg²⁺ ions essential for RNA hydrolysis. As part of our ongoing research on RNase H inhibitors, we developed 23 novel N-hydroxypyridinedione (HPD) analogues. Specifically, 17 HPD imines, 4 HPD oximes, 1 2,6-diamino-4-((substituted)oxy)pyrimidine 1-oxide derivative, and 1 barbituric acid analogue were designed, synthesized, and tested for their anti-HBV activity. The HPD derivatives could be docked in the RNase H active site to coordinate the two Mg²⁺ ions and effectively inhibited viral replication in cellular assays. The 50% effective concentration (EC₅₀) values of these HPD compounds ranged from 0.5 to 73 μM, while the 50% cytotoxic concentration (CC₅₀) values ranged from 15 to 100 μM, resulting in selectivity indexes (SIs) up to 112. Furthermore, the novel HPD derivatives exhibited favourable pharmacokinetic-relevant characteristics, including high cellular permeability, good aqueous solubility, and overall drug-like properties. These findings indicate that HPD imines and oximes possess substantial antiviral potency and selectivity against HBV, underscoring the potential of the HPD scaffold as a promising framework for the development of next-generation anti-HBV agents.