ABSTRACT
In an effort to identify a new class of druglike HIV-1 protease inhibitors, four different stereopure ß-hydroxy γ-lactam-containing inhibitors have been synthesized, biologically evaluated, and cocrystallized. The impact of the tether length of the central spacer (two or three carbons) was also investigated. A compound with a shorter tether and (3R,4S) absolute configuration exhibited high activity with a K(i) of 2.1 nM and an EC(50) of 0.64 µM. Further optimization by decoration of the P1' side chain furnished an even more potent HIV-1 protease inhibitor (K(i) = 0.8 nM, EC(50) = 0.04 µM). According to X-ray analysis, the new class of inhibitors did not fully succeed in forming two symmetric hydrogen bonds to the catalytic aspartates. The crystal structures of the complexes further explain the difference in potency between the shorter inhibitors (two-carbon spacer) and the longer inhibitors (three-carbon spacer).
Subject(s)
HIV Protease Inhibitors/chemistry , HIV Protease/chemistry , Lactams/chemistry , Caco-2 Cells , Cell Membrane Permeability , Crystallography, X-Ray , HIV Protease/metabolism , HIV Protease Inhibitors/chemical synthesis , HIV Protease Inhibitors/pharmacology , HIV-1/drug effects , HIV-1/enzymology , Humans , Lactams/chemical synthesis , Lactams/pharmacology , Models, Molecular , Molecular Structure , Stereoisomerism , Structure-Activity RelationshipABSTRACT
MOE-Dock (Docking software) was used to predict the binding modes of 10 novel and potent 5-substituted amino-2,4-diamino-8-chloropyrimido-[4,5-b]quinolines (compounds I-X) as part of our antimalarial drug development programme. This was done by analyzing the interaction of these compounds with the active sites of 11 enzymes present in Plasmodium falciparum and based on this, effective binding was observed to enzyme P. falciparum glutathione reductase (PfGR). The binding scores for compounds I-X with PfGR were also congruent with their antimalarial activity. Three additional analogs were then designed and synthesized based on the above docking study and the pharmacophoric requirements for this class.
Subject(s)
Antimalarials/chemistry , Antimalarials/pharmacology , Quinolines/chemistry , Quinolines/pharmacology , Animals , Binding Sites , Glutathione Reductase/drug effects , Models, Molecular , Plasmodium falciparum/drug effects , Plasmodium falciparum/enzymologyABSTRACT
Novel 5-substituted amino-2,4-diamino-8-chloropyrimido-[4,5-b]quinolines were designed based on a pharmacophore developed for potent antimalarial activity using Chem-X and MOE softwares. The designed molecules were synthesized by following a novel route and were evaluated by Rane's test for blood schizonticidal activity in mice infected by Plasmodium berghei. Based on the Mean Survival Time (MST) data, of the nine compounds evaluated, three had curative potential when compared with chloroquine.
