Dataset Information

Pharmacological Validation of N-Myristoyltransferase as a Drug Target in Leishmania donovani.

ABSTRACT: Visceral leishmaniasis (VL), caused by the protozoan parasites Leishmania donovani and L. infantum, is responsible for ?30?000 deaths annually. Available treatments are inadequate, and there is a pressing need for new therapeutics. N-Myristoyltransferase (NMT) remains one of the few genetically validated drug targets in these parasites. Here, we sought to pharmacologically validate this enzyme in Leishmania. A focused set of 1600 pyrazolyl sulfonamide compounds was screened against L. major NMT in a robust high-throughput biochemical assay. Several potent inhibitors were identified with marginal selectivity over the human enzyme. There was little correlation between the enzyme potency of these inhibitors and their cellular activity against L. donovani axenic amastigotes, and this discrepancy could be due to poor cellular uptake due to the basicity of these compounds. Thus, a series of analogues were synthesized with less basic centers. Although most of these compounds continued to suffer from relatively poor antileishmanial activity, our most potent inhibitor of LmNMT (DDD100097, K _i of 0.34 nM) showed modest activity against L. donovani intracellular amastigotes (EC₅₀ of 2.4 ?M) and maintained a modest therapeutic window over the human enzyme. Two unbiased approaches, namely, screening against our cosmid-based overexpression library and thermal proteome profiling (TPP), confirm that DDD100097 (compound 2) acts on-target within parasites. Oral dosing with compound 2 resulted in a 52% reduction in parasite burden in our mouse model of VL. Thus, NMT is now a pharmacologically validated target in Leishmania. The challenge in finding drug candidates remains to identify alternative strategies to address the drop-off in activity between enzyme inhibition and in vitro activity while maintaining sufficient selectivity over the human enzyme, both issues that continue to plague studies in this area.

SUBMITTER: Corpas-Lopez V

PROVIDER: S-EPMC6332449 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Pharmacological Validation of N-Myristoyltransferase as a Drug Target in Leishmania donovani.

Corpas-Lopez Victoriano V Moniz Sonia S Thomas Michael M Wall Richard J RJ Torrie Leah S LS Zander-Dinse Dorothea D Tinti Michele M Brand Stephen S Stojanovski Laste L Manthri Sujatha S Hallyburton Irene I Zuccotto Fabio F Wyatt Paul G PG De Rycker Manu M Horn David D Ferguson Michael A J MAJ Clos Joachim J Read Kevin D KD Fairlamb Alan H AH Gilbert Ian H IH Wyllie Susan S

ACS infectious diseases 20181112 1

Visceral leishmaniasis (VL), caused by the protozoan parasites Leishmania donovani and L. infantum, is responsible for ∼30 000 deaths annually. Available treatments are inadequate, and there is a pressing need for new therapeutics. N-Myristoyltransferase (NMT) remains one of the few genetically validated drug targets in these parasites. Here, we sought to pharmacologically validate this enzyme in Leishmania. A focused set of 1600 pyrazolyl sulfonamide compounds was screened against L. major NMT ...[more]

PMID: 30380837

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Project description:AimsThe parasite, Leishmania donovani is responsible for lethal visceral leishmaniasis (VL) in humans. There is a need to investigate novel medicines as antileishmanial drugs, as medication currently introduced for leishmaniasis may cause resistance, serious side-effects, chemical instability and high cost. Therefore, this computational study was designed to explore potential phytochemical inhibitors against Leishmania donovani squalene synthase (LdSQS) enzyme, a drug target.Main methodsMultiple sequence alignment was carried to detect conserved regions across squalene synthases from different Leishmania spp. Their evolutionary relationships were studied by generating phylogenetic tree. Homology modeling method was used to build a three dimensional model of the protein. The validated model was explored by docking simulation with the phytochemicals of interest to identify the most potent inhibitors. Two reported inhibitors were used as references in the virtual screening. The top hit compounds (binding energy less than -9 kcal/mol) were further subjected to intermolecular interaction analysis, pharmacophore modeling, pharmacokinetic and toxicity prediction.Key findingsSeven phytochemicals displayed binding energies less than -9 kcal/mol hence demonstrating ability to be strongly bound to the active site of LdSQS to inhibit the enzymatic activity. Ancistrotanzanine B demonstrated the lowest binding affinity of -9.83 kcal/mol superior to reported inhibitors in literature. Conserved two aspartate rich regions and two signatory motifs were found in the L. donovani squalene synthase by multiple sequence alignment. In addition, study of pharmacophore modeling confirmed that top hit phytochemicals and the reported inhibitor (E5700) share common chemical features for their biochemical interaction with LdSQS. Among seven phytochemicals, 3-O-methyldiplacol showed admissible physicochemical, pharmacokinetic and toxicity predictions compared to the reported inhibitors. All seven phytochemicals satisfied in silico prediction criteria for oral bioavailability.SignificanceBased on the current study, these hits can be further structurally optimized and validated under laboratory conditions to develop antileishmanial drugs.

Dataset Information

Pharmacological Validation of N-Myristoyltransferase as a Drug Target in Leishmania donovani.

Publications

Pharmacological Validation of N-Myristoyltransferase as a Drug Target in Leishmania donovani.

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