New thiourea derivatives that target the episomal silencing SMC5 protein to inhibit HBx-dependent viral DNA replication and gene transcription.

Antivirals such as nucleotide analogs (NAs) are potent inhibitors of hepatitis B virus (HBV) replication. However, NAs fail to diminish the signaling and mitogenic activities of the transactivator HBx protein. Earlier we have shown that thiourea derivative IR-415 (DSA-00) targeted HBx to down-regulate its target viral and host genes. However, the molecular mechanism of its antiviral action is poorly understood. Here we investigated the anti-HBV properties of DSA-00 and its new derivatives in cell culture models. DSA-00 and its derivatives DSA-02 and DSA-09 not only suppressed HBV DNA levels similar to well-known antiviral Entecavir but also diminished the expression of pgRNA and secretion of HBsAg and HBeAg. Apparently, the three DSA derivatives inhibited the viral pregenomic RNA expression by stabilizing the episomal DNA silencing protein SMC5, suppressed transcription from viral and host gene promoters, and normalized intracellular CDK2 activity. As none the compounds are reportedly cytotoxic, thiourea derivatives could be good candidates for developing future antivirals for a functional cure of hepatitis B infection. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13337-024-00895-6.