The Inhibitory Effect of Resveratrol from Reynoutria japonica on MNV-1, a Human Norovirus Surrogate

As a natural nonflavonoid polyphenol compound, resveratrol is the main functional component of Reynoutria japonica and has anti-inflammatory, antioxidant, antiviral, and other physiological activities. In this study, the effect of resveratrol on the viability of RAW264.7 cells was examined, and murine norovirus (MNV-1) was used as a surrogate for human norovirus to evaluate the inhibitory effect of resveratrol. The concentrations of resveratrol resulting in 50% cytotoxicity (CC₅₀) for RAW264.7 cells were 21.32 and 24.97 μg/mL after 24 and 48 h of incubation, respectively, and resveratrol at a concentration lower than the half-effective inhibitory concentration (EC₅₀) could not damage cell DNA. The EC₅₀ of resveratrol on MNV-1 in infected RAW264.7 cells was determined to equal 5.496 μg/mL. After RAW264.7 cells, virus, and a fresh mixture of virus and RAW264.7 cells were treated with resveratrol solution for 1 h (denoted cell pre-treatment, virus pre-treatment, and mixture coprocessing), the RAW264.7 cells obtained after cell pre-treatment exhibited lower virus infection, and MNV-1 obtained after virus pre-treatment and mixture coprocessing showed a decreased infectious capacity. The inhibition ratio of resveratrol on MNV-1 did not significantly differ between the treatments at 4 and 25 °C or among the various pH values except for the lower acidic condition (pH 2). TEM revealed significant changes in the morphology of MNV-1 after treatment with resveratrol, and molecular docking indicated that resveratrol strongly binds to the viral capsid protein of MNV-1. In addition, resveratrol regulated the expression of cytokine that protects against MNV-1 infection. Therefore, at a lower concentration, resveratrol, a natural component from Reynoutria japonica, exerts an inhibitory effect on MNV-1 growth and could be used as a safe additive in food products to improve the nutritional status and control norovirus.