A derivative of soyasapogenol, 22beta-methoxyolean-12-ene-3beta, 24(4beta)-diol (ME3738), ameliorates liver injury induced by Concanavalin A in mice. We examined whether ME3738 has independent antiviral effects against hepatitis C virus (HCV) using an established HCV replication model that expresses the full-length genotype 1a HCV complementary DNA plasmid (pT7-flHCV-Rz) under the control of a replication-defective adenoviral vector expressing T7 polymerase. Hepatocellular carcinoma (HepG2) cells, human hepatoma (Huh7) cells, or monkey kidney (CV-1) cells were transfected with pT7-flHCV-Rz, and infected with adenoviral vector expressing T7 polymerase. ME3738 or interferon-alpha (IFN-alpha) was added thereafter and then protein and RNA were harvested from the cells at 9 days after infection. HCV-positive and HCV-negative strands were measured by real-time reverse-transcription polymerase chain reaction and HCV core protein expression was measured using an enzyme-linked immunosorbent assay. The messenger RNA levels of innate antiviral response-related genes were assessed using real-time reverse-transcription polymerase chain reaction. ME3738 dose-dependently reduced HCV-RNA and core protein in hepatocyte-derived cell lines. The antiviral effect was more pronounced in HepG2 than in Huh7 cells. ME3738 increased messenger RNA levels of interferon-beta (IFN-beta) and of IFN-stimulated genes (2'-5' oligoadenylate synthetase, myxovirus resistance protein A [MxA]). Interferon-beta knockdown by small interfering RNA abrogated the anti-HCV effect of ME3738. Moreover, the anti-HCV effects were synergistic when ME3738 was combined with IFN-alpha.
Conclusion: ME3738 has antiviral effects against HCV. The enhancement of autocrine IFN-beta suggests that ME3738 exerts antiviral action along the type I IFN pathway. This anti-HCV action by ME3738 was synergistically enhanced when combined with IFN-alpha. ME3738 might be a useful anti-HCV drug either with or without IFN-alpha.