ABSTRACT
Leishmaniasis is a tropical disease found in more than 90 countries. The drugs available to treat this disease have nonspecific action and high toxicity. In order to develop novel therapeutic alternatives to fight this ailment, pteridine reductase 1 (PTR1) and dihydrofolate reductase-thymidylate synthase (DHF-TS) have been targeted, once Leishmania is auxotrophic for folates. Although PTR1 and DHFR-TS from other protozoan parasites have been studied, their homologs in Leishmania chagasi have been poorly characterized. Hence, this work describes the optimal conditions to express the recombinant LcPTR1 and LcDHFR-TS enzymes, as well as balanced assay conditions for screening. Last but not the least, we show that 2,4 diaminopyrimidine derivatives are low-micromolar competitive inhibitors of both enzymes (LcPTR1 Ki = 1.50-2.30 µM and LcDHFR Ki = 0.28-3.00 µM) with poor selectivity index. On the other hand, compound 5 (2,4-diaminoquinazoline derivative) is a selective LcPTR1 inhibitor (Ki = 0.47 µM, selectivity index = 20).
Subject(s)
Enzyme Inhibitors/pharmacology , Leishmania infantum/enzymology , Multienzyme Complexes/antagonists & inhibitors , Oxidoreductases/antagonists & inhibitors , Thymidylate Synthase/antagonists & inhibitors , Catalysis , Chromatography, Affinity , Cloning, Molecular , Drug Evaluation, Preclinical , Electrophoresis, Polyacrylamide Gel , Escherichia coli/genetics , Inhibitory Concentration 50 , Multienzyme Complexes/genetics , Multienzyme Complexes/isolation & purification , Multienzyme Complexes/metabolism , Oxidoreductases/genetics , Oxidoreductases/isolation & purification , Oxidoreductases/metabolism , Tetrahydrofolate Dehydrogenase/genetics , Tetrahydrofolate Dehydrogenase/isolation & purification , Tetrahydrofolate Dehydrogenase/metabolism , Thymidylate Synthase/genetics , Thymidylate Synthase/isolation & purification , Thymidylate Synthase/metabolismABSTRACT
Adenosine receptors have been considered as potential targets for drug development, but one of the main obstacles to this goal is to selectively inhibit one receptor subtype over the others. This subject is particularly crucial for adenosine A2b receptor antagonists (AdoRA2B). The structureactivity relationships of xanthine derivatives which are AdoRA2B have been comprehensively investigated, but the steric and electronic requirements of deazaxanthine AdoRA2B have not been described from a quantitative standpoint of view. Herein we report our efforts to shorten this knowledge gap through 2D-QSAR (HQSAR) and 3D-QSAR (CoMFA) approaches. The good statistical quality (HQSAR--r(2) = 0.85, q(2)(LOO) = 0.77; CoMFA r(2) = 0.86, q(2) = 0.70) and predictive ability (r(2) = (pred1) = 0.78, r(2)(pred2) = 0.78 and r(2) = (pred1) = 0.70, r(2) = (pred2) = 0.70,respectively) of the models, along with the information provided by contribution and contour maps hints their usefulness to the design of more potent 9-deazaxanthine derivatives.
