The Antiviral Effect of Ephedrine Alkaloids-Free Ephedra Herb Extract, EFE, on Murine Coronavirus Growth in the Lung and Liver of Infected Mice

Abstract

Ephedrine alkaloids-free Ephedra Herb extract (EFE) was developed to reduce the adverse effects of Ephedra Herb, a constituent drug in Kampo medicines. It is produced by decocting Ephedra Herb with hot water and excluding the ephedrine alkaloids. EFE has analgesic and anti-cancer effects and inhibits respiratory viruses in vitro. To assess the pharmacological action of EFE in vivo, we evaluated its effect on the replication of murine hepatitis virus (MHV), a coronavirus that causes hepatitis, pneumonia, and severe acute respiratory syndrome-like symptoms, within infected mice. On Day 0, MHV was inoculated intranasally into female BALB/C mice, and EFE was orally administered once/day at 350-700 mg/kg (n = 10/group) starting 1 h after inoculation until Day 5. Through a plaque assay, MHV was detected on Day 5 in the lung and liver in all inoculated mice, but the titer was significantly lower in the EFE groups as compared with untreated control mice. Although not statistically significant, the clinical score for respiratory irregularity tended to be lower in the EFE treatment groups. In conclusion, EFE inhibits MHV replication in an in vivo mouse model of human coronavirus infection and exerts pharmacological action in the lung and liver.

Keywords: hepatitis; murine hepatitis virus-infected mouse model; pneumonia; severe acute respiratory syndrome-like symptoms.

Figure 1

Viral titers recovered from the lung (a) and liver (b) and clinical score for the respiratory irregularity (c) of MHV-infected mice with or without EFE treatment. Viral titer (×10² plaque-forming unit (PFU)/g tissue) is presented as both individual scores and mean ± SD (n = 10 for NI and EFE groups; n = 9 for MI), and the clinical score is presented as both individual scores and the median with IQR (n = 10 for all groups). A p value of < 0.01 via the one-way ANOVA with Bonferroni’s multiple comparisons test is seen for (a) and (b), and p < 0.01 via the Kruskal–Wallis test with Dunn’s multiple comparison test is seen for (c). Different letters indicate a significant difference among groups.