In Vitro and In Vivo Antiamebic Activity of Iron-Targeting Polypyridine Compounds against Enteric Protozoan Parasite Entamoeba histolytica.

The infectious protozoan parasite Entamoeba histolytica is responsible for amebiasis causing colitis and liver abscesses, which is an epidemic in developing countries. To develop a drug discovery strategy targeting the iron source required for the proliferation of E. histolytica, an untapped chemical group consisting of low-molecular-weight compounds with metal-binding affinity was investigated. Electrochemically neutral polypyridine compounds, PHN-R2, that showed specific Fe(II)-binding affinity and growth inhibitory ability against E. histolytica were identified. Furthermore, the iron-dependent IC50 values of PHN-R2 and the spectrometric analytical data of their iron complexes clarified the relationship between the antiamebic activity and the iron-targeting specificity. Notably, when PHN-H2 was administrated to E. histolytica-infected hamsters as an animal model of amebiasis, it exhibited a prominent therapeutic efficacy to completely cure liver abscesses without serious side effects. Deciphering the antiamebic activity of iron-targeting compounds in vitro and in vivo provides valuable insights into the development of a next-generation drug against amebiasis.