Dehydrojuncusol, a Natural Phenanthrene Compound Extracted from Juncus maritimus, Is a New Inhibitor of Hepatitis C Virus RNA Replication

Recent emergence of direct acting antivirals (DAAs) targeting hepatitis C virus (HCV) proteins has considerably enhanced the success of antiviral therapy. However, the appearance of DAA resistant-associated variants is a cause of treatment failure, and the high cost of DAAs renders the therapy not accessible in countries with inadequate medical infrastructures. Therefore, search for new inhibitors and with lower cost of production should be pursued. In this context, crude extract of Juncus maritimus Lam. was shown to exhibit high antiviral activity against HCV in cell culture. Bio-guided fractionation allowed isolating and identifying the active compound, dehydrojuncusol. A time-of-addition assay showed that dehydrojuncusol significantly inhibited HCV infection when added after virus inoculation of HCV genotype 2a (EC 50 = 1.35 µM). This antiviral activity was confirmed with a HCV subgenomic replicon and no effect on HCV pseudoparticle entry was observed. Antiviral activity of dehydrojuncusol was also demonstrated in primary human hepatocytes. No in vitro toxicity was observed at active concentrations. Dehydrojuncusol is also efficient on HCV genotype 3a and can be used in combination with sofosbuvir. Interestingly, dehydrojuncusol was able to inhibit replication of two frequent daclatasvir resistant mutants (L31M or Y93H in NS5A). Finally, resistant mutants to dehydrojuncusol were obtained and showed that HCV NS5A protein is the target of the molecule. In conclusion, dehydrojuncusol, a natural compound extracted from J. maritimus, inhibits infection of different HCV genotypes by targeting NS5A protein and is active against HCV resistant variants frequently found in patients with treatment failure.