Effects of Thai piperaceae plant extracts on Neospora caninum infection

Neosporosis has a worldwide distribution and causes economic losses in farming, particularly by increasing the risk of abortion in cattle. This study investigated the effects of Thai piperaceae (Piper betle, P. nigrum, and P. sarmentosum) extracts on Neospora caninum infections in vitro and in vivo. In an in vitro parasite growth assay based on the green fluorescent protein (GFP) signal, P. betle was the most effective extract at inhibiting parasite growth in human foreskin fibroblast cells (IC50 of GFP-expressing N. caninum parasites, 22.1 mu g/ml). The P. betle extract, at 25 mu g per ml, inhibited parasite invasion into host cells. Furthermore, in two independent experiments, treating N. caninum-infected mice with the P. betle extract for 7 days post-infection increased their survival. In trial one, the anti-N. caninum effects of the P. betle extract reduced the mouse clinical scores for 30 days post-infection (dpi). The survival rate of the mice treated with 400 mg/kg was 100% compared with 66.6% for those treated with 100 mg/kg and the non-treated controls. In trial two, treating the infected mice with the P. betle extract increased their survival at 50 dpi. All mice in the non-treatment group died; however, the survival rates of the 400 mg/kg-treated and 100 mg/kg-treated mice were 83.3% and 33.3%, respectively. Also, a trend towards a reduced parasite burden was noted in the brains of the P. betle extract-treated mice, compared with the control mice. Therefore P. betle extract has potential as a medicinal plant for treating neosporosis. (C) 2017 Elsevier B.V. All rights reserved.