慢性乙肝是肝硬化和肝细胞癌的高危因素，核cccDNA难以清除导致临床药物不可治愈。课题基于前期发现珊瑚来源briarane型二萜具有显著抑制HBV病毒和cccDNA等活性，设计以调控HBV感染周期和抑制HBV关键靶标为导向，通过briarane型生源相关萜类结构多样性与新颖性研究和多模型HBV感染细胞评价，建立活性分子的构-效关系。选择具有显著抑制HBV活性新型萜类分子，针对乙肝病毒复制各环节以及化合物的抗HBV特点，评价化合物对HBV复制模板cccDNA水平、HBV基因转录和转录后修饰、core蛋白表达、HBV逆转录过程，以及宿主细胞基因表达谱变化等分子机制。同时，制备briarane分子探针，以期发现抗病毒新靶标或信号通路，并以人肝嵌合HBV动物阐明抑制HBV病毒复制功效。通过挖掘抗慢性HBV新型海洋药源分子潜力研究，为海洋萜类分子的药用功能开拓新方向。

Hepatitis B virus (HBV) is a significant global pathogen, and still represents a major health threat with about 350 million chronically infected individuals worldwide. HBV infection leads to a wide spectrum of liver disease ranging from acute to chronic viral hepatitis, which is often associated with the development of liver cirrhosis and hepatocellular carcinoma. The ultimate goal of chronic hepatitis B virus therapy is full eradication of the virus from the liver. However, this is rarely achieved with the clinically available first-line agents due to the inability to eliminate covalently closed circular DNA (cccDNA), which persists in the nucleus of infected hepatocyte cells. Therefore, it is urgent to search structurally novel natural products which are able to target on cccDNA and finally to eliminate HBV infection. Our previous examination of anti-HBV compounds from marine benthic organisms revealed that marine gorgonian derived briarane-type diterpenoids exerted significant inhibition against HBV-DNA, HBV-RNA, and cccDNA in HepAD38 and Hepg2.2.15 cell lines. In this proposal, the bioassays for the regulation of HBV life-cycle and inhibition of cccDNA are oriented for the discovery of bioactive and structurally novel marine terpenoids which are potent for the inhibition of HBV. Two steps are involved in the chemical investigation: (1) to extend the chemical diversity and novelty of briarane-type diterpenoids, which are followed by the anti-HBV evaluation under multiple HBV-infected cell models. The structure-activity relationships are analyzed to uncover the functional groups within the briarane scaffold and to achieve the most active compounds; (2) to extend the biogenetically related terpenoids including cembranoids and biscembranoids/isobiscembranoids which are isolated from marine soft coral and gorgonian species. Comparison of the anti-HBV activities with the diverse terpenoid scaffolds will be discussed. Briarane-type analogues with the inhibition of cccDNA will be selected in priority for further mode of action investigation. The molecular pathways and mediated factors derived from host and virus which are able to regulate cccDNA will be clarified. In addition, briarane-probes are synthesized to uncover new targets for the regulation of cccDNA formation. Present project aims to discover structurally novel anti-HBV marine natural products, and to explore marine terpenoids for pharmaceutical usage.