(+)-Methyl (1<i>R</i>,2<i>S</i>)‑2-{[4-(4-Chlorophenyl)-4-hydroxypiperidin-1-yl]methyl}-1-phenylcyclopropanecarboxylate [(+)-MR200] Derivatives as Potent and Selective Sigma Receptor Ligands: Stereochemistry and Pharmacological Properties

Methoxycarbonyl-1-phenyl-2-cyclopropylmethyl based derivatives <i>cis</i>-(+)-<b>1a</b> [<i>cis</i>-(+)-MR200], <i>cis</i>-(−)-<b>1a [</b><i>cis</i>-(−)-MR201], and <i>trans</i>-(±)-<b>1a</b> [<i>trans</i>-(±)-MR204], have been identified as new potent sigma (σ) receptor ligands. In the present paper, novel enantiomerically pure analogues were synthesized and optimized for their σ receptor affinity and selectivity. Docking studies rationalized the results obtained in the radioligand binding assay. Absolute stereochemistry was unequivocally established by X-ray analysis of precursor <i>trans</i>-(+)-<b>5a</b> as camphorsulfonyl derivative <b>9</b>. The most promising compound, <i>trans</i>-(+)-<b>1d</b>, showed remarkable selectivity over a panel of more than 15 receptors as well as good chemical and enzymatic stability in human plasma. An in vivo evaluation evidenced that <i>trans</i>-(+)-<b>1d</b>, in contrast to <i>trans</i>-(−)-<b>1d</b>, <i>cis</i>-(+)-<b>1d</b>, or <i>cis</i>-(−)-<b>1d</b>, which behave as σ₁ antagonists, exhibited a σ₁ agonist profile. These data clearly demonstrated that compound <i>trans</i>-(+)-<b>1d</b>, due to its σ₁ agonist activity and favorable receptor selectivity and stability, provided an useful tool for the study of σ₁ receptors

Antitrypanosomal Lead Discovery: Identification of a Ligand-Efficient Inhibitor of Trypanosoma cruzi CYP51 and Parasite Growth

Chagas disease is caused by the intracellular protozoan parasite Trypanosomal cruzi, and current drugs are lacking in terms of desired safety and efficacy profiles. Following on a recently reported high-throughput screening campaign, we have explored initial structure–activity relationships around a class of imidazole-based compounds. This profiling has uncovered compounds <b>4c</b> (NEU321) and <b>4j</b> (NEU704), which are potent against in vitro cultures of T. cruzi and are greater than 160-fold selective over host cells. We report in vitro drug metabolism and properties profiling of <b>4c</b> and show that this chemotype inhibits the T. cruzi CYP51 enzyme, an observation confirmed by X-ray crystallographic analysis. We compare the binding orientation of <b>4c</b> to that of other, previously reported inhibitors. We show that <b>4c</b> displays a significantly better ligand efficiency and a shorter synthetic route over previously disclosed CYP51 inhibitors, and should therefore be considered a promising lead compound for further optimization

Protozoan Parasite Growth Inhibitors Discovered by Cross-Screening Yield Potent Scaffolds for Lead Discovery

Tropical protozoal infections are a significant cause of morbidity and mortality worldwide; four in particular (human African trypanosomiasis (HAT), Chagas disease, cutaneous leishmaniasis, and malaria) have an estimated combined burden of over 87 million disability-adjusted life years. New drugs are needed for each of these diseases. Building on the previous identification of NEU-617 (<b>1</b>) as a potent and nontoxic inhibitor of proliferation for the HAT pathogen (<i>Trypanosoma brucei</i>), we have now tested this class of analogs against other protozoal species: <i>T. cruzi</i> (Chagas disease), <i>Leishmania major</i> (cutaneous leishmaniasis), and <i>Plasmodium falciparum</i> (malaria). Based on hits identified in this screening campaign, we describe the preparation of several replacements for the quinazoline scaffold and report these inhibitors’ biological activities against these parasites. In doing this, we have identified several potent proliferation inhibitors for each pathogen, such as 4-((3-chloro-4-((3-fluorobenzyl)­oxy)­phenyl)­amino)-6-(4-((4-methyl-1,4-diazepan-1-yl)­sulfonyl)­phenyl)­quinoline-3-carbonitrile (NEU-924, <b>83</b>) for <i>T. cruzi</i> and <i>N</i>-(3-chloro-4-((3-fluorobenzyl)­oxy)­phenyl)-7-(4-((4-methyl-1,4-diazepan-1-yl)­sulfonyl)­phenyl)­cinnolin-4-amine (NEU-1017, <b>68</b>) for <i>L. major</i> and <i>P. falciparum</i>

Identification and Characterization of Hundreds of Potent and Selective Inhibitors of <i>Trypanosoma brucei</i> Growth from a Kinase-Targeted Library Screening Campaign

<div><p>In the interest of identification of new kinase-targeting chemotypes for target and pathway analysis and drug discovery in <i>Trypanosomal brucei,</i> a high-throughput screen of 42,444 focused inhibitors from the GlaxoSmithKline screening collection was performed against parasite cell cultures and counter-screened against human hepatocarcinoma (HepG2) cells. In this way, we have identified 797 sub-micromolar inhibitors of <i>T. brucei</i> growth that are at least 100-fold selective over HepG2 cells. Importantly, 242 of these hit compounds acted rapidly in inhibiting cellular growth, 137 showed rapid cidality. A variety of <i>in silico</i> and <i>in vitro</i> physicochemical and drug metabolism properties were assessed, and human kinase selectivity data were obtained, and, based on these data, we prioritized three compounds for pharmacokinetic assessment and demonstrated parasitological cure of a murine bloodstream infection of <i>T. brucei rhodesiense</i> with one of these compounds (NEU-1053). This work represents a successful implementation of a unique industrial-academic collaboration model aimed at identification of high quality inhibitors that will provide the parasitology community with chemical matter that can be utilized to develop kinase-targeting tool compounds. Furthermore these results are expected to provide rich starting points for discovery of kinase-targeting tool compounds for <i>T. brucei,</i> and new HAT therapeutics discovery programs.</p></div

Summary of average properties of the overall screening set and specific compounds.

<p>Summary of average properties of the overall screening set and specific compounds.</p

The project assay cascade.

<p>The project assay cascade.</p

Compound composite scoring schema.

a<p>“Fast” is defined as pEC₅₀≥6 at 18 h.</p>b<p>“Cidal” is defined as pEC₉₉≥6 in the reversibility experiments. Only compounds that were rapidly acting and/or had an MPO score ≥4 were tested in the cidality assay; compounds not tested in the cidal assay are assigned a score of 0.</p><p>Compound composite scoring schema.</p

Scatter plot showing the average pEC₅₀ at the 18 hour time point for the 242 compounds tested in the cidality assay.

<p>Compounds are colored on the basis of reversibility behavior (cidal = red; static = green).</p

Representation of 797 hit compounds.

<p>(a) Plot of LLE vs LE, color coded based on MPO score (min = 1.1, Red; max = 5.75, Green). (b) plot of molecular weight vs cLogP. Compounds with MPO score ≥4 are colored green.</p

Highest-ranking cluster representatives for clusters 1-24.

<p>Each compound's composite score is shown in parentheses.</p