ABSTRACT
Coccidiosis is the major cause of morbidity and mortality in the poultry industry. Protozoan parasites of the genus Eimeria invade the intestinal lining of the avian host causing tissue pathology, poor weight gain, and in some cases mortality. Resistance to current anticoccidials has prompted the search for new therapeutic agents with potent in vitro and in vivo activity against Eimeria. Recently, we reported the synthesis and biological activity of potent imidazo[1,2-a]pyridine anticoccidial agents. Antiparasitic activity is due to inhibition of a parasite specific cGMP-dependent protein kinase (PKG). In this study, we report the synthesis and anticoccidial activity of a second set of such compounds, focusing on derivatization of the amine side chain at the imidazopyridine 7-position. From this series, several compounds showed subnanomolar in vitro activity and commercial levels of in vivo activity. However, the potential genotoxicity of these compounds precludes them from further development.
Subject(s)
Coccidiostats/chemical synthesis , Coccidiostats/pharmacology , Pyridines/chemical synthesis , Pyridines/pharmacology , Animals , Cyclic GMP-Dependent Protein Kinases/antagonists & inhibitors , Eimeria/drug effects , Magnetic Resonance Spectroscopy , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacology , Spectrometry, Mass, Electrospray IonizationABSTRACT
Coccidiosis is the major cause of morbidity and mortality in the poultry industry. Protozoan parasites of the genus Eimeria invade the intestinal lining of the avian host causing tissue pathology, poor weight gain, and in some cases mortality. Resistance to current anticoccidials has prompted the search for new therapeutic agents with potent in vitro and in vivo activity against Eimeria. Antiparasitic activity is due to inhibition of a parasite specific cGMP-dependent protein kinase (PKG). In this study, we present the synthesis and biological activity of imidazo[1,2-a]pyridine anticoccidial agents. From this series, several compounds showed subnanomolar in vitro activity and commercial levels of in vivo activity. However, the potential genotoxicity of these compounds precludes them from further development.
Subject(s)
Coccidiostats/chemical synthesis , Coccidiostats/pharmacology , Eimeria/drug effects , Imidazoles/chemical synthesis , Imidazoles/pharmacology , Pyridines/chemical synthesis , Pyridines/pharmacology , Animals , Biological Availability , Coccidiostats/chemistry , Cyclic GMP-Dependent Protein Kinases/antagonists & inhibitors , Cyclic GMP-Dependent Protein Kinases/metabolism , Eimeria/physiology , Imidazoles/chemistry , Inhibitory Concentration 50 , Pyridines/chemistryABSTRACT
Compounds 10a (IC50 110 pM) and 21 (IC50 40 pM) are the most potent inhibitors of Eimeria tenella cGMP-dependent protein kinase activity reported to date and are efficacious in the in vivo antiparasitic assay when administered to chickens at 12.5 and 6.25 ppm levels in the feed. However, both compounds are positive in the Ames microbial mutagenesis assay which precludes them from further development as antiprotozoal agents in the absence of negative lifetime rodent carcinogenicity studies.
