Effects of Rubiadin isolated from Prismatomeris connata on anti‐hepatitis B virus activity in vitro

Prismatomeris connata was a kind of Rubiaceae plant for treatment of hepatitis, hepatic fibrosis and silicosis. Whereas, the effective components of Prismatomeris connata remains unexplored. The aim of this study was to investigate the inhibitory effects and mechanisms of Rubiadin isolated from Prismatomeris connata against HBV using HepG2.2.15 cells. The levels of hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and hepatitis B core antigen (HBcAg) in the supernatants or cytoplasm were examined using by enzyme‐linked immunosorbent assay. HBV DNA was qualified q‐PCR. Rubiadin was isolated by silica gel column. The structure of the compound was elucidated by HPLC, FT‐IR, ¹H‐NMR, ¹³C‐NMR and identified as 1,3‐Dihydroxy‐2‐methyl‐9, 10‐anthraquinone. Rubiadin significantly decreased HBeAg,HBcAg secretion level and inhibit HBV DNA replication. Rubiadin inhibits the proliferation of the cells and HBx protein expression in a dose‐dependent manner. The intracellular calcium concentration was significantly reduced. These results demonstrated that Rubiadin could inhibit HepG2.2.15 cells proliferation, reduce the level of HBx expression, and intracellular free calcium, which might become a novel anti‐HBV drug candidate.