ABSTRACT
Screening of our chemical library to discover new molecules exhibiting in vitro activity against the invasion of host cells by Eimeria tenella revealed a lead compound with an IC50 of 15µM. Structure-activity relationship studies were conducted with 34 newly synthesized compounds to identify more active molecules and enhance in vitro activity against the parasite. Four compounds were more effective in inhibiting MDBK cell invasion in vitro than the lead compound.
Subject(s)
Coccidiosis/drug therapy , Coccidiostats/chemical synthesis , Coccidiostats/pharmacology , Eimeria tenella/drug effects , Pyridones/pharmacology , Pyrimidinones/pharmacology , Animals , Cattle , Cell Survival/drug effects , Coccidiostats/chemistry , Dose-Response Relationship, Drug , Molecular Structure , Parasitic Sensitivity Tests , Pyridones/chemical synthesis , Pyridones/chemistry , Pyrimidinones/chemical synthesis , Pyrimidinones/chemistry , Structure-Activity RelationshipABSTRACT
Toxoplasmosis is a disease of prominent health concern that is caused by the protozoan parasite Toxoplasma gondii. Proliferation of T. gondii is dependent on its ability to invade host cells, which is mediated in part by calcium-dependent protein kinase 1 (CDPK1). We have developed ATP competitive inhibitors of TgCDPK1 that block invasion of parasites into host cells, preventing their proliferation. The presence of a unique glycine gatekeeper residue in TgCDPK1 permits selective inhibition of the parasite enzyme over human kinases. These potent TgCDPK1 inhibitors do not inhibit the growth of human cell lines and represent promising candidates as toxoplasmosis therapeutics.
Subject(s)
Coccidiostats/chemical synthesis , Protein Kinase Inhibitors/chemical synthesis , Protein Kinases/metabolism , Protozoan Proteins/antagonists & inhibitors , Pyrazoles/chemical synthesis , Pyrimidines/chemical synthesis , Toxoplasma/drug effects , Cell Line , Cell Proliferation/drug effects , Coccidiostats/chemistry , Coccidiostats/pharmacology , Crystallography, X-Ray , Drug Resistance , Enzyme Assays , Humans , Models, Molecular , Molecular Structure , Naphthalenes/chemical synthesis , Naphthalenes/chemistry , Naphthalenes/pharmacology , Piperidines/chemical synthesis , Piperidines/chemistry , Piperidines/pharmacology , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Protozoan Proteins/metabolism , Pyrazoles/chemistry , Pyrazoles/pharmacology , Pyrimidines/chemistry , Pyrimidines/pharmacology , Structure-Activity Relationship , Toxoplasma/enzymologyABSTRACT
In poultry farming, anticoccidial drugs are widely used as feed additives for the prevention and treatment of coccidiosis. Because coccidiostats and veterinary medicines, in general, are often poorly absorbed, manure from treated animals may contain high concentrations of these compounds. Experimental studies have shown that the uptake of veterinary medicines by plants from soil containing contaminated manure may occur. This leads to several questions regarding the impact on the environment, resistance problems, and public health and allergy issues. This work describes the development of a quantification method for coccidiostats in vegetables. Vegetables were spiked at 100 µg kg(-1) (dry weight) with coccidiostats (monensin, narasin, lasalocid A, salinomycin, diclazuril, and nicarbazin) in order to optimize the extraction and clean-up. Possible critical factors (e.g., extraction solvent) were statistically examined by linear regression with the use of Plackett-Burman and full factorial designs. Final extracts were analyzed with ultra-performance liquid chromatography tandem mass spectrometry operating in multiple-reaction monitoring mode. Both the synthetic and ionophoric coccidiostats could be determined in a single run with an analysis time of 5 min. The developed method was validated taking into account the requirements of the Commission Decision 2002/657/EC as a guideline. The method is regarded as applicable for its intended purposes with quantification limits between 0.30 and 2.98 µg kg(-1). This method could be used to establish possible maximum residue limits for coccidiostats in vegetables, as already exist for eggs, meat, and milk.
Subject(s)
Chromatography, High Pressure Liquid/methods , Coccidiostats/analysis , Ionophores/analysis , Tandem Mass Spectrometry/methods , Vegetables/chemistry , Coccidiostats/chemical synthesis , Food Contamination/analysisABSTRACT
Toxoplasmosis causes significant morbidity and mortality, and yet available medicines are limited by toxicities and hypersensitivity. Because improved medicines are needed urgently, rational approaches were used to identify novel lead compounds effective against Toxoplasma gondii enoyl reductase (TgENR), a type II fatty acid synthase enzyme essential in parasites but not present in animals. Fifty-three compounds, including three classes that inhibit ENRs, were tested. Six compounds have antiparasite MIC(90)s < or = 6 microM without toxicity to host cells, three compounds have IC(90)s < 45 nM against recombinant TgENR, and two protect mice. To further understand the mode of inhibition, the cocrystal structure of one of the most promising candidate compounds in complex with TgENR has been determined to 2.7 A. The crystal structure reveals that the aliphatic side chain of compound 19 occupies, as predicted, space made available by replacement of a bulky hydrophobic residue in homologous bacterial ENRs by Ala in TgENR. This provides a paradigm, conceptual foundation, reagents, and lead compounds for future rational development and discovery of improved inhibitors of T. gondii.
Subject(s)
Coccidiostats/chemical synthesis , Enoyl-(Acyl-Carrier-Protein) Reductase (NADH)/antagonists & inhibitors , Nitriles/chemical synthesis , Phenyl Ethers/chemical synthesis , Pyridines/chemical synthesis , Toxoplasma/drug effects , Animals , Cells, Cultured , Coccidiostats/chemistry , Coccidiostats/pharmacology , Crystallography, X-Ray , Cytochrome P-450 Enzyme Inhibitors , Fibroblasts/drug effects , Fibroblasts/parasitology , Humans , In Vitro Techniques , Mice , Microbial Sensitivity Tests , Microsomes, Liver/metabolism , Models, Molecular , Molecular Structure , Nitriles/chemistry , Nitriles/pharmacology , Nitrobenzenes/chemical synthesis , Nitrobenzenes/chemistry , Nitrobenzenes/pharmacology , Phenyl Ethers/chemistry , Phenyl Ethers/pharmacology , Pyridines/chemistry , Pyridines/pharmacology , Structure-Activity Relationship , Toxoplasma/enzymology , Toxoplasmosis/drug therapyABSTRACT
Novel 2,3-diarylindoles bearing an amine substituent at the indole 5- and 6-positions have been synthesized and evaluated as anticoccidial agents in both in vitro and in vivo assays. Both subnanomolar in vitro activity and broad spectrum in vivo potency were detected for several compounds, particularly compound 27.
Subject(s)
Coccidiostats/chemical synthesis , Indoles/chemical synthesis , Animals , Coccidiosis/drug therapy , Coccidiosis/enzymology , Coccidiosis/parasitology , Coccidiostats/pharmacology , Cyclic GMP-Dependent Protein Kinases/antagonists & inhibitors , Eimeria tenella/drug effects , Eimeria tenella/enzymology , Eimeria tenella/growth & development , Indoles/pharmacology , Poultry/parasitology , Pyridines/chemical synthesisABSTRACT
A series of ethyl 6-arylmethoxy-7-alkoxy-4-hydroxy-3-quinolinecarboxylates was synthesized as anticoccidial medicine, and their structures were characterized by 1H NMR, MS, and IR spectra. Anticoccidial activities of these compounds were evaluated according to the anticoccidial index method. The results indicated that five of these compounds exhibited anticoccidial activities against Eimeria tenella in the chicken's diet with a dose of 27 mg/kg. In particular, the anticoccidial index of ethyl 6-(2,5-dimethylbenzyloxy)-7-methoxy-4-hydroxy-3-quinolinecarboxylate and ethyl 6-(2,5-dimethylbenzyloxy)-7-ethoxy-4-hydroxy-3-quinolinecarboxylate was 169.3 and 175.1, respectively, which indicated that the two compounds have high anticoccidial activity.
Subject(s)
Coccidiostats/chemical synthesis , Eimeria tenella/drug effects , Quinolines/chemical synthesis , Animals , Chickens , Coccidiostats/chemistry , Coccidiostats/therapeutic use , Food , Poultry Diseases/parasitology , Poultry Diseases/prevention & control , Protozoan Infections, Animal/parasitology , Protozoan Infections, Animal/prevention & control , Quinolines/chemistry , Quinolines/therapeutic useABSTRACT
Novel 5,6-diarylimidazo[2,1-b][1,3]thiazoles bearing an amine substituent at the imidazothiazole 2-position have been synthesized and evaluated as anticoccidial agents in both in vitro and in vivo assays. Both subnanomolar in vitro activity and broad spectrum in vivo potency were detected for several compounds, particularly compound 10.
Subject(s)
Coccidiostats/chemical synthesis , Coccidiostats/pharmacology , Imidazoles/chemical synthesis , Imidazoles/pharmacology , Thiazoles/chemical synthesis , Thiazoles/pharmacology , Animals , Coccidiostats/chemistry , Combinatorial Chemistry Techniques , Cyclic GMP-Dependent Protein Kinases/antagonists & inhibitors , Eimeria/drug effects , Imidazoles/chemistry , Molecular Structure , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Thiazoles/chemistryABSTRACT
Diaryl-(4-piperidinyl)-pyrrole derivatives bearing cyclic amine substituents have been synthesized and evaluated as anticoccidial agents. Improvements in potency of Et-PKG inhibition, such as azetidine derivative 3a, and broad spectrum anticoccidial activities in feed, such as morpholine derivative 8c, have been achieved.
Subject(s)
Coccidiosis/drug therapy , Coccidiostats/pharmacology , Eimeria/drug effects , Pyrroles/pharmacology , Animals , Chickens , Coccidiostats/chemical synthesis , Cyclic GMP-Dependent Protein Kinases/antagonists & inhibitors , Eimeria/enzymology , Female , Molecular Structure , Oocysts/drug effects , Oocysts/physiology , Protein Kinase Inhibitors/pharmacology , Pyrroles/chemical synthesis , Pyrroles/chemistry , Structure-Activity RelationshipABSTRACT
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
In this work we report a QSAR model that discriminates between chemically heterogeneous classes of anticoccidial and non-anticoccidial compounds. For this purpose we used the Markovian Chemicals in silico Design (MARCH-INSIDE) approach J. Mol. Mod.2002, 8, 237-245; J. Mol. Mod.2003, 9, 395-407]. Linear discriminant analysis allowed us to fit the discriminant function. This function correctly classifies 86.67% of anticoccidial compounds and 96.23% of inactive compounds in the training series. Overall classification is 94.12%. We validated the model by means of an external predicting series, with 86.96% of global predictability. Remarkably, the present model is based on topological as well as configuration-dependent molecular descriptors. Therefore, the model performs timely calculations and allows discrimination between Z/E and chiral isomers. Finally, to exemplify the use of the model in practice we report the prediction and experimental assay of trans-2-(2-nitrovinyl)furan. It is notable that lesion control was 72.86% at mg/kg of body weight with respect to 60% at 125 mg/kg for amprolium (control drug). The back-projection map for this compound predicts a high level of importance for the double bond and for the nitro group in the trans position. We conclude that the MARCH-INSIDE approach enables the accurate fast track identification of anticoccidial hits. Moreover, trans-2-(2-nitrovinyl)furan seems to be a promising drug for the treatment of coccidiosis.
Subject(s)
Coccidiostats/chemical synthesis , Coccidiostats/pharmacology , Furans/chemical synthesis , Furans/pharmacology , Vinyl Compounds/chemical synthesis , Vinyl Compounds/pharmacology , Animals , Body Weight/drug effects , Chickens , Eimeria tenella/drug effects , Female , Models, Molecular , Quantitative Structure-Activity Relationship , Reproducibility of ResultsABSTRACT
Compounds 10a-10d and 10i are very potent inhibitors of Eimeria tenella cGMP-dependent protein kinase (0.081-0.32 nM) and are very efficacious antiparasitic agents in vivo when administered to chickens at 12.5-25 ppm levels in the feed.
Subject(s)
Coccidiostats/chemical synthesis , Coccidiostats/pharmacology , Imidazoles/chemical synthesis , Imidazoles/pharmacology , Pyridines/chemistry , Pyridines/chemical synthesis , Pyridines/pharmacology , Animals , Coccidiostats/chemistry , Eimeria/drug effects , Imidazoles/chemistry , Molecular Structure , Structure-Activity RelationshipABSTRACT
2-(4-Fluorophenyl)-3-(4-pyridinyl)-5-substituted pyrroles were prepared and evaluated as anticoccidial agents in both in vitro and in vivo assays. Among the compounds evaluated, the dimethylamine-substituted pyrrole 19a is the most potent inhibitor of Eimeria tenella PKG (cGMP-dependent protein kinase). Further SAR studies on the side chain of the 2-pyrrolidine nitrogen did not enhance in vivo anticoccidial activity.
Subject(s)
Coccidiostats/chemical synthesis , Coccidiostats/pharmacology , Pyrroles/chemical synthesis , Pyrroles/pharmacology , Animals , Coccidiostats/chemistry , Cyclic GMP-Dependent Protein Kinases/antagonists & inhibitors , Eimeria tenella/drug effects , Eimeria tenella/enzymology , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Pyrroles/chemistry , Structure-Activity RelationshipABSTRACT
We report the preparation and antiparasitic activity in vitro and in vivo of a series of isoflavone derivatives related to genistein. These analogues retain the 5,7-dihydroxyisoflavone core of genistein: direct genistein analogues (2-H isoflavones), 2-carboethoxy isoflavones, and the precursor deoxybenzoins were all evaluated. Excellent in vitro activity against Cryptosporidium parvum was observed for both classes of isoflavones in cell cultures, and the lead compound 19, RM6427, shows high in vivo efficacy against an experimental infection.
Subject(s)
Coccidiostats/chemical synthesis , Cryptosporidium parvum/drug effects , Isoflavones/chemical synthesis , Animals , Cattle , Cell Line, Tumor , Coccidiostats/pharmacology , Cryptosporidiosis/drug therapy , Cryptosporidium parvum/isolation & purification , Female , Genistein/analogs & derivatives , Genistein/chemical synthesis , Genistein/pharmacology , Gerbillinae , Humans , Immunocompromised Host , Isoflavones/pharmacology , Male , Structure-Activity RelationshipABSTRACT
Several analogs of 2,3-diaryl pyrroles were synthesized and evaluated as inhibitors of Eimeria tenella cGMP-dependent protein kinase and in in vivo anticoccidial assays. A 4-fluorophenyl group enhances both in vitro and in vivo activities. The most potent analogs are the 5-(N-methyl, N-ethyl, and N-methylazetidine methyl) piperidyl derivatives 12, 23, and 34. These compounds have a broad spectrum of activity. Based on the in vivo efficacy and cost of synthesis, the N-ethyl analog 23 was chosen as a novel anticoccidial agent for a field trial.
Subject(s)
Coccidiostats/chemical synthesis , Cyclic GMP-Dependent Protein Kinases/antagonists & inhibitors , Protozoan Proteins/antagonists & inhibitors , Pyrroles/chemical synthesis , Animals , Biological Availability , Chickens , Coccidiosis/drug therapy , Coccidiostats/pharmacokinetics , Coccidiostats/pharmacology , Eimeria , Half-Life , Inhibitory Concentration 50 , Pyrroles/pharmacokinetics , Pyrroles/pharmacology , Structure-Activity RelationshipABSTRACT
Toxoplasma gondii is the most common cause of secondary CNS infections in immunocompromised persons such as AIDS patients. The major route of adenosine metabolism in T. gondii is direct phosphorylation to adenosine 5'-monophosphate (AMP) catalyzed by the enzyme adenosine kinase (EC 2.7.1.20). Adenosine kinase in T. gondii is significantly more active than any other purine salvage enzyme in this parasite and has been established as a potential chemotherapeutic target for the treatment of toxoplasmosis. Subversive substrates of T. gondii,but not the human, adenosine kinase are preferentially metabolized to their monophosphorylated forms and become selectively toxic to the parasites but not their host. 6-Benzylthioinosine (BTI) was identified as an excellent subversive substrate of T. gondii adenosine kinase. Herein, we report the synthesis of new analogues of BTI as subversive substrates for T. gondii adenosine kinase. These new subversive substrates were synthesized starting from tribenzoyl protected d-ribose. To accomplish the lead optimization process, a divergent and focused combinatorial library was synthesized using a polymer-supported trityl group at the 5'-position. The combinatorial library of 20 compounds gave several compounds more active than BTI. Structure-activity relationship studies showed that substitution at the para position plays a crucial role. To investigate the reasons for this discrimination, substrates with different substituents at the para position were studied by molecular modeling using Monte Carlo Conformational Search followed by energy minimization of the enzyme-ligand complex.
Subject(s)
Adenosine Kinase/metabolism , Thioinosine/chemical synthesis , Toxoplasma/enzymology , Adenosine Kinase/chemistry , Adenosine Kinase/deficiency , Animals , Cells, Cultured , Coccidiostats/chemical synthesis , Coccidiostats/chemistry , Coccidiostats/pharmacology , Combinatorial Chemistry Techniques , Humans , Models, Molecular , Structure-Activity Relationship , Thioinosine/analogs & derivatives , Thioinosine/chemistry , Thioinosine/pharmacology , Toxoplasma/drug effectsABSTRACT
The synthesis of several acridinic thioethers is described. Compounds prepared were tested in vitro as potential drugs against the opportunistic infection known as cryptosporidiosis. With a view to predict activity, the quantitative structure-activity relationships were investigated. Correlations between experimental data and either log P or pKa are discussed.
Subject(s)
Acridines/chemical synthesis , Coccidiostats/chemical synthesis , Cryptosporidium parvum/drug effects , Acridines/pharmacology , Acridines/therapeutic use , Animals , Animals, Newborn , Cattle , Cell Line , Coccidiostats/pharmacology , Coccidiostats/therapeutic use , Cryptosporidiosis/drug therapy , Cryptosporidiosis/parasitology , Cryptosporidium parvum/growth & development , Feces/parasitology , Hydrogen Bonding , Magnetic Resonance Spectroscopy , Structure-Activity RelationshipABSTRACT
Several quinazoline derivatives containing substituted thiosemicarbazido and S-methylisothiosemicarbazido groups at the 2-position and at both the 2- and 4-positions have been synthesized. Treatment of the S-methylthiosemicarbazides with morpholine or diethylamine did not give the corresponding guanidines. Instead, they underwent cyclodesulfurization into the condensed ring systems, [1,2,4]triazolo[4,3-a]quinazolinones and bis-[1,2,4]triazolo[4,3-a:4'.3'-c]quinazolines. Evaluation of the products for antitoxoplasmosis effect by studying the ultrastructure morphology of the organisms using scanning electron microscopy (SEM) indicated their efficacy in causing structural deformity of Toxoplasma gondii. Such a deformity plays an important role in obstructing the entry of the organisms into host cells.
Subject(s)
Coccidiostats/chemical synthesis , Quinazolines/chemical synthesis , Toxoplasma/drug effects , Triazoles/chemical synthesis , Animals , Anti-Infective Agents/pharmacology , Coccidiostats/pharmacology , Mice , Pyrimethamine/pharmacology , Quinazolines/pharmacology , Quinazolinones , Toxoplasma/ultrastructure , Toxoplasmosis, Animal/drug therapy , Toxoplasmosis, Animal/parasitology , Triazoles/pharmacologyABSTRACT
[formula: see text] The proposed structure of fudecalone (1), an anticoccidial drimane sesquiterpene, was synthesized as a racemate in six steps starting from a known phthalide (5). Interestingly, our synthetic 1 showed conformation 1b, while the natural one was reported as 1a, and the NMR spectral data were not identical.
Subject(s)
Coccidiostats/chemical synthesis , Naphthalenes/chemical synthesis , Coccidiostats/chemistry , Magnetic Resonance Spectroscopy , Molecular Structure , Naphthalenes/chemistryABSTRACT
The reactions of 3-alkyl(aryl)-4-phenylamino-4,5-dihydro-1H-1,2,4-triazol-5-ones with appropriate alkyl halides via sodio derivatives were studied and the corresponding 1-alkyl-3-alkyl(aryl)-4-phenylamino-4,5-dihydro-1H-1,2,4-traizol-5 -ones were synthesized. Next, the new compounds were tested for their in vitro antimicrobial activities.