An evaluation of the inhibitory effects against rotavirus infection of edible plant extracts

Background: Rotaviruses are the single most important cause of severe diarrhea in young children worldwide. The developments of specific, potent and accessible antiviral treatments that restrain rotavirus infection remain important to control rotavirus disease. Methods: 150 plant extracts with nutritional applications were screened in vitro on MA-104 cells for their antiviral activity against rhesus rotavirus (RRV). One extract (Aspalathus linearis (Burm.f.) R.Dahlgren) was also tested for its effect on the loss of transepithelial resistance (TER) of Caco-2 cells caused by simian rotavirus (SA-11) infection. Results: Aqueous extracts of Nelumbo nucifera Gaertn. fruit, Urtica dioica L. root, Aspalathus linearis (Burm.f.) R. Dahlgren leaves, Glycyrrhiza glabra L. root and Olea europaea L. leaves were found to have strong significant antiviral activity with a 50% inhibitory concentration (IC50) < 300 mu g/ml. The pure compound 18 beta-glycyrrhetinic acid from Glycyrrhiza glabra was found to have the strongest antiviral activity (IC50 46 mu M), followed by luteolin and vitexin from Aspalathus linearis (IC50 respectively 116 mu M and 129 mu M) and apigenin-7-O-glucoside from Melissa officinalis (IC50 150 mu M). A combination of Glycyrrhiza glabra L. + Nelumbo nucifera Gaertn. and Urtica dioica L. + Nelumbo nucifera Gaertn. showed synergy in their anti-viral activities. Aspalathus linearis (Burm.f.) R. Dahlgren showed no positive effect on the maintenance of the TER. Conclusions: These results indicate that nutritional intervention with extracts of Nelumbo nucifera Gaertn., Aspalathus linearis (Burm.f.) R. Dahlgren, Urtica dioica L., Glycyrrhiza glabra L. and Olea europaea L. might be useful in the treatment of diarrhea caused by rotavirus infection.