Evaluation of the anticoccidial activity of secondary metabolites in alpine plants using a mouse Eimeria model, Eimeria krijgsmanni.

Coccidiosis is a highly pathogenic disease caused by a protozoan parasite, severely impacting the global livestock economy. Due to the emergence of drug resistance to current anticoccidial agents, developing novel anticoccidial compounds, such as plant secondary metabolites, is necessary, as previously studied. The objective of the present study is to deepen the understanding of the anticoccidial activity of these natural compounds and to investigate their potential as anticoccidial drugs. Here, we examined the anticoccidial activity of 27 natural compounds, containing 28 secondary metabolites, derived from 8 alpine plants, using the mouse Eimeria species, Eimeria krijgsmanni. E. krijgsmanni sporozoites were exposed to the compounds at a final concentration of 100 μM. After incubation for 24 h, the viability of sporozoites was assessed using trypan blue staining. Twelve compounds, containing 14 secondary metabolites, reduced the sporozoite viability by 4.5%-69.5% and seven compounds were newly recognized to have anticoccidial activity against E. krijgsmanni. The compounds containing β-sitosterol showed the most potent effect. Although further studies are needed to analyze the in vivo efficacy, these anticoccidial compounds have potential as effective anticoccidial drugs.