In Vitro Antiviral Activity of Tyrosinase from Mushroom Against Hepatitis C Virus

Tyrosinases from a commercial protein extract and directly isolated from white mushrooms were purified in order to obtaining the well-known tyrosinase from () of 45 kDa and a newly discovered 50 kDa tyrosinase isoform (), and tested showing high antiviral activity against the hepatitis C virus for the first time. Cell toxicity and antiviral activity of tyrosinases were determined in cultured Huh 5-2 liver tumor cells transfected with a replicon system (a plasmid that includes all non-structural hepatitis C virus proteins and replicates autonomously). was able to inhibit the replication of the hepatitis C virus without inducing toxicity in liver cells. In addition, the post-translational isoform showed higher antiviral capacity than the former (up to 10 times greater), also exhibiting 10 times higher activity than the commercial drug Ribavirin. This antiviral activity was directly proportional to the enzymatic activity of tyrosinases, as no antiviral capacity was observed in the inactive form of the enzymes. The tyrosinases approach could represent a new antiviral inhibition mechanism, through a plausible catalytic mechanism of selective hydroxylation of the key role of tyrosine residues in viral proteases.