Suppression of norovirus by natural phytochemicals from Aloe vera and Eriobotryae Folium

Abstract

Human norovirus (HuNoV) is the major cause of viral foodborne diseases, but no effective medication is currently available. This study reported the anti-norovirus activity of the natural extracts of Aloe vera (AV) and Eriobotryae Folium (EF). Murine norovirus 1 (MNV-1), a surrogate virus of HuNoV, was preincubated with AV or EF extracts and then subjected to plaque assays in RAW 264.7 cells. Pretreatment of AV and EF extracts effectively suppressed the infectivity of MNV-1 with an estimated half-maximal inhibitory concentration (IC50) of 0.778 and 1.196 mg/mL, respectively. Cytotoxicity of AV and EF was not observed in RAW 264.7 cells. Anthraquinone compounds found in AV, aloin and aloe-emodin showed moderate antiviral effects. When fresh cabbage was inoculated with MNV-1 on the surface, AV and EF treatments as well as aloin and aloe-emodin at 25 °C for 30 min suppressed the MNV-1 infectivity on cabbage surface as effectively as in solution, suggesting the antiviral activity of AV and EF can be applied on food surface. These results showed AV and EF may serve as potentially effective and safe norovirus inhibitors due to their relatively low cytotoxicity, which allows them to be prepared as food-safe formulations.