Evaluation of Natural Compounds of Plant Origin for Inactivation of Enteric Viruses.

Essential oils (EOs) and some of their main compounds have demonstrated extensive antimicrobial activity in a wide range of food spoilage or pathogenic fungi, yeast and bacteria. The aim of this study was to assess the antiviral activity of Zataria multiflora Boiss. (zataria) and Origanum vulgare (oregano) EOs on hepatitis A virus (HAV) and the effect of thymol, an active compound of Thymus vulgaris and oregano, on norovirus surrogates, feline calicivirus (FCV) and murine norovirus (MNV), and HAV. Initially, each virus at titers of ca. 6 log TCID/ml was exposed to different concentrations of natural compounds and incubated for 2 h at 37 °C. Treatment with oregano and zataria EOs resulted in slight reductions on HAV infectivity with a maximum reduction of less than 0.5 log TCID/ml at 0.1 % zataria EO. Thymol was effective in reducing the titers of norovirus surrogates in a dose-dependent manner. Concentrations of thymol at 0.5 and 1 % reduced FCV titers to undetectable levels, while for MNV, thymol at concentrations of 1 and 2 % resulted in reductions of 1.66 and 2.45 log TCID/ml, respectively. However, for HAV, no effect was observed at any of the concentrations tested. These results improve the knowledge about the antiviral activity of EO and their compounds and their potential in food sanitation.