Antiviral effect of persimmon (Diospyros kaki Thunb. cv. Cheongdo-Bansi) extracts on murine norovirus

Norovirus infections are one of the most significant causes of foodborne outbreaks worldwide. This study aimed to investigate the antiviral effects of persimmon (Diospyros kaki Thunb. cv. Cheongdo-Bansi) extracts on murine norovirus (MNV). Persimmon extracts obtained by solvent extraction and squeezing, prior to freeze-drying were evaluated by determining the yield and tannin contents. The cytotoxicity and antiviral effect of persimmon extracts were determined using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and a time-of-addition assay, respectively. The yield and tannin content were in following order: methanol > water > ethanol > acetone > juice extracts and juice > acetone > water > ethanol > methanol extracts, respectively. The concentrations of methanol, ethanol, acetone, water, and juice extracts were determined to be 800, 800, 600, 200, and 400 μg/mL, respectively. The MNV titer was significantly reduced by 1.65 log plaque forming unit (PFU)/mL with 18% reduction in plaque formation in group pre-treated with water extract. Furthermore, the significant reductions in MNV titer by 2.14, 1.69, and 2.96 log PFU/mL were observed in groups co-treated with acetone, water, and juice extracts, respectively with plaque formation inhibition of 22-40%. However, there were no significant antiviral effects in the post-treated groups. This study suggests the potential use of persimmon extracts as anti-noroviral agents.