Discovery of Sulfonamidebenzamides as Selective Apoptotic CHOP Pathway Activators of the Unfolded Protein Response

Cellular proteins that fail to fold properly result in inactive or disfunctional proteins that can have toxic functions. The unfolded protein response (UPR) is a two-tiered cellular mechanism initiated by eukaryotic cells that have accumulated misfolded proteins within the endoplasmic reticulum (ER). An adaptive pathway facilitates the clearance of the undesired proteins; however, if overwhelmed, cells trigger apoptosis by upregulating transcription factors such as C/EBP-homologous protein (CHOP). A high throughput screen was performed directed at identifying compounds that selectively upregulate the apoptotic CHOP pathway while avoiding adaptive signaling cascades, resulting in a sulfonamidebenzamide chemotype that was optimized. These efforts produced a potent and selective CHOP inducer (AC₅₀ = 0.8 μM; XBP1 > 80 μM), which was efficacious in both mouse embryonic fibroblast cells and a human oral squamous cell cancer cell line, and demonstrated antiproliferative effects for multiple cancer cell lines in the NCI-60 panel

Discovery of a Plasmodium falciparum Glucose-6-phosphate Dehydrogenase 6‑phosphogluconolactonase Inhibitor (<i>R</i>,<i>Z</i>)‑<i>N</i>‑((1-Ethylpyrrolidin-2-yl)methyl)-2-(2-fluorobenzylidene)-3-oxo-3,4-dihydro‑2<i>H</i>‑benzo[<i>b</i>][1,4]thiazine-6-carboxamide (ML276) That Reduces Parasite Growth in Vitro

A high-throughput screen of the NIH’s MLSMR collection of ∼340000 compounds was undertaken to identify compounds that inhibit Plasmodium falciparum glucose-6-phosphate dehydrogenase (<i>Pf</i>G6PD). <i>Pf</i>G6PD is important for proliferating and propagating P. falciparum and differs structurally and mechanistically from the human orthologue. The reaction catalyzed by glucose-6-phosphate dehydrogenase (G6PD) is the first, rate-limiting step in the pentose phosphate pathway (PPP), a key metabolic pathway sustaining anabolic needs in reductive equivalents and synthetic materials in fast-growing cells. In P. falciparum, the bifunctional enzyme glucose-6-phosphate dehydrogenase-6-phosphogluconolactonase (<i>Pf</i>GluPho) catalyzes the first two steps of the PPP. Because P. falciparum and infected host red blood cells rely on accelerated glucose flux, they depend on the G6PD activity of <i>Pf</i>GluPho. The lead compound identified from this effort, (<i>R</i>,<i>Z</i>)-<i>N</i>-((1-ethylpyrrolidin-2-yl)­methyl)-2-(2-fluorobenzylidene)-3-oxo-3,4-dihydro-2<i>H</i>-benzo­[<i>b</i>]­[1,4]­thiazine-6-carboxamide, <b>11</b> (ML276), is a submicromolar inhibitor of <i>Pf</i>G6PD (IC₅₀ = 889 nM). It is completely selective for the enzyme’s human isoform, displays micromolar potency (IC₅₀ = 2.6 μM) against P. falciparum in culture, and has good drug-like properties, including high solubility and moderate microsomal stability. Studies testing the potential advantage of inhibiting <i>Pf</i>G6PD in vivo are in progress

Maximizing Lipophilic Efficiency: The Use of Free-Wilson Analysis in the Design of Inhibitors of Acetyl-CoA Carboxylase

This paper describes the design and synthesis of a novel series of dual inhibitors of acetyl-CoA carboxylase 1 and 2 (ACC1 and ACC2). Key findings include the discovery of an initial lead that was modestly potent and subsequent medicinal chemistry optimization with a focus on lipophilic efficiency (LipE) to balance overall druglike properties. Free-Wilson methodology provided a clear breakdown of the contributions of specific structural elements to the overall LipE, a rationale for prioritization of virtual compounds for synthesis, and a highly successful prediction of the LipE of the resulting analogues. Further preclinical assays, including in vivo malonyl-CoA reduction in both rat liver (ACC1) and rat muscle (ACC2), identified an advanced analogue that progressed to regulatory toxicity studies

Discovery of ML314, a Brain Penetrant Nonpeptidic β‑Arrestin Biased Agonist of the Neurotensin NTR1 Receptor

The neurotensin 1 receptor (NTR1) is an important therapeutic target for a range of disease states including addiction. A high-throughput screening campaign, followed by medicinal chemistry optimization, led to the discovery of a nonpeptidic β-arrestin biased agonist for NTR1. The lead compound, 2-cyclopropyl-6,7-dimethoxy-4-(4-(2-methoxyphenyl)-piperazin-1-yl)­quinazoline, <b>32</b> (ML314), exhibits full agonist behavior against NTR1 (EC₅₀ = 2.0 μM) in the primary assay and selectivity against NTR2. The effect of <b>32</b> is blocked by the NTR1 antagonist SR142948A in a dose-dependent manner. Unlike peptide-based NTR1 agonists, compound <b>32</b> has no significant response in a Ca²⁺ mobilization assay and is thus a biased agonist that activates the β-arrestin pathway rather than the traditional G_<i>q</i> coupled pathway. This bias has distinct biochemical and functional consequences that may lead to physiological advantages. Compound <b>32</b> displays good brain penetration in rodents, and studies examining its in vivo properties are underway