Finally, cells were washed and incubated in complete culture medium at 37°C for 45 hours. Infections were scored by measuring luciferase activity. Huh-7 cells were infected Pifithrin-�� in vitro with purified

HCVcc in 24-well plates for 1 hour at 4°C in the presence of either DMSO, or 50 μM of EGCG, or 500 μg/mL of porcine intestinal heparin. Cells were washed with PBS, and total RNA was extracted using the NucleoSpin RNA II kit (Macherey-Nagel, Düren, Germany), according to the manufacturer’s instructions. HCV RNA was quantified by quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR) assay as described previously. 27 Before analyzing the potential antiviral effect of EGCG on HCV, we first determined the toxicity of EGCG EPZ-6438 cost on Huh-7 cells (Fig. 1A). Although some toxicity began to be observed at 100 μM, a concentration of 50 μM was shown to have no toxic effect, even after 72

hours. The half lethal dose was between 150 and 175 μM in Huh-7 cells, depending on the exposition time. To test the effect of EGCG on the HCV life cycle, the molecule was added to the medium during HCVcc infection. Interestingly, more than 1 log10 decrease of HCVcc infectious titers was observed in cells treated with 50 μM of EGCG (Fig. 1B). To confirm our results on HCV, we used a recombinant HCV expressing the Renilla luciferase (i.e., JFH1-Luc) to infect cells in the presence of increasing concentrations of EGCG. A dose-dependent decrease of JFH1-Luc infection was observed (Fig. 1C). The half-maximal inhibitory concentration (IC50) was estimated to approximately 5 μM, and the 90% inhibitory concentration (IC90) was close to 50 μM. Thus, the therapeutic index of EGCG is approximately 30. Together, these results show that EGCG has an antiviral activity against HCV. Other catechins extracted from green tea include (+)-catechin, EC, ECG, and EGC (Fig. 1D). The toxicity

of each catechin was determined individually (Supporting Fig. 1). Then, each catechin was tested for its antiviral activity. (+)-Catechin and EC did not display any anti-HCV activity (Fig. 1E). In contrast, both ECG and EGC exhibited an inhibition of HCV infection of approximately 40% and 80%, respectively. Furthermore, we confirmed the antiviral medchemexpress activity of EGCG by using EGCG provided by another manufacturer. To test whether EGCG would be a general viral inhibitor, experiments were performed with two other members of the Flaviviridae family (BVDV and YFV) and another unrelated virus (SINV) (Fig. 2A). HSV-1 was used as a positive control, because EGCG has an antiviral activity against this virus 12 (Fig. 2B). In contrast to HCV and HSV-1, EGCG treatment at 50 μM has no antiviral effect on BVDV, YFV, and SINV, indicating that the effect of EGCG could not be generalized to the Flaviviridae family in our experimental conditions.