Junceellolide B, a novel inhibitor of Hepatitis B virus.

HBV infection is a common cause of liver disease with a high burden worldwide. Current therapeutic strategy relies on interferon and nucleos(t)ide-type drugs with the limitation of functional cure. In this study, a structure-based screening of marine natural products from an in-house library was performed to hit HBV inhibitors, and the gorgonian-derived briarane-type diterpenoids showed inhibitory effects against HBV DNA replication in HepAD38 cells. Preliminary analyses of structure-activity relationship demonstrated that a briarane-based scaffold with an 3E,5(16)-diene and a chlorine-substitution at C-6 is required for the anti-HBV activity. Junceellolide B is one of the potent HBV inhibitors exhibiting efficient reduction of HBsAg and HBeAg production in HBV infected HepG2-NTCP cells with a dose-dependent manner (p < 0.001). It also significantly reduced the secreted HBV DNA, HBV RNA, and HBeAg in HepAD38 cells with the EC values of 0.83, 2.87 and 7.75 μM, respectively. Mechanistically, junceellolide B potently inhibited HBV RNA transcription without promoting HBV RNA degradation. RNA-seq analysis indicated that junceellolide B significantly decreased HBV cccDNA-transcripted products accompanying stable down-regulation of the expression of RNA polymerase II related host transcription factors (ZBED6 and ZBTB7B). These findings suggest junceellolide B to be a transcription inhibitor of cccDNA and a promising lead for the development of new anti-HBV agent.