Anti-hepatitis C virus activity of a crude extract from longan (Dimocarpus longan Lour.) leaves

抄録

Hepatitis C is a disease caused by hepatitis C virus (HCV) that causes chronic infection, cirrhosis, and hepatocellular carcinoma. The current standard therapy is a combination of pegylated interferon-α plus ribavirin with NS3 protease inhibitors. Addition of NS3 protease inhibitors increases response rates; however, this addition is associated with significant side effects and an increase in the overall cost of the treatment. Therefore, there remains a need to develop safe and inexpensive drugs for the treatment of HCV infections. In this study, we examined the antiviral activity of a crude extract from Dimocarpus longan leaves against HCV (genotype 2a strain JFH1). The D. longan crude extract exhibited anti-HCV activity with a 50% effective concentration (EC₅₀) of 19.4 μg/ml without cytotoxicity. A time-of-addition study demonstrated that the crude extract exerts anti-HCV activity at both the entry and post-entry steps. The crude extract markedly blocked viral entry step through a direct virucidal effect with a marginal inhibition of virion assembly. The co-treatment of the crude extract with cyclosporine A or telaprevir, an NS3 protease inhibitor, had additive and synergistic antiviral effects, respectively. Our findings suggest that the D. longan crude extract may be a candidate of the add-on therapy for HCV infection.