Jeffrey C. Pelletier

Gonadotropin releasing hormone receptor antagonists

Corticotropin-releasing hormone (CRH), CRH-related peptides, and CRH receptors play major roles in coordinating the behavioral, endocrine, autonomic, and immune responses to stress. The wide influence of the CRH system on physiological processes in both brain and periphery implicates the respective peptides in the pathophysiology of numerous disorders characterized by dysregulated stress responses. The potential use of CRH antagonists is presently under intense investigation. Selective antagonists have been used experimentally to elucidate the role of CRH-related peptides in disease processes, such as anxiety and depression, sleep disorders, addictive behavior, inflammatory disorders, acute and chronic neurodegeneration, and preterm labor.

Mitsunobu reaction modifications allowing product isolation without chromatography: application to a small parallel library

Readily available reagents, triphenylphosphine resin and di-t-butylazodicarboxylate, were used in Mitsunobu reactions and the byproducts were removed without chromatography. The new modification was utilized to prepare a small, parallel, solution phase library.

(1-(4-(Naphthalen-2-yl)pyrimidin-2-yl)piperidin-4-yl)methanamine: A Wingless β-Catenin Agonist That Increases Bone Formation Rate

A high-throughput screening campaign to discover small molecule leads for the treatment of bone disorders concluded with the discovery of a compound with a 2-aminopyrimidine template that targeted the Wnt beta-catenin cellular messaging system. Hit-to-lead in vitro optimization for target activity and molecular properties led to the discovery of (1-(4-(naphthalen-2-yl)pyrimidin-2-yl)piperidin-4-yl)methanamine (5, WAY-262611). Compound 5 has excellent pharmacokinetic properties and showed a dose dependent increase in the trabecular bone formation rate in ovariectomized rats following oral administration.

2-phenyl-4-piperazinylbenzimidazoles: orally active inhibitors of the gonadotropin releasing hormone (GnRH) receptor.

Antagonism of the gonadotropin releasing hormone (GnRH) receptor has shown positive clinical results in numerous reproductive tissue disorders such as endometriosis, prostate cancer and others. Traditional therapy has been limited to peptide agonists and antagonists. Recently, small molecule GnRH antagonists have emerged as potentially new treatments. This article describes the discovery of 2-phenyl-4-piperazinylbenzimidazoles as small molecule GnRH antagonists with nanomolar potency in in vitro binding and functional assays, excellent bioavailability (rat %F>70) and demonstrated oral activity in a rat model having shown significant serum leuteinizing hormone (LH) suppression.

Novel (4-Piperidin-1-yl)-phenyl Sulfonamides as Potent and Selective Human β3 Agonists

A series of novel (4-piperidin-1-yl)-phenyl sulfonamides was prepared and evaluated for their biological activity on the human beta(3)-adrenergic receptor (AR). Replacement of the 3,4-dihydroxyl group of the catechol moiety with 4-hydroxyl-3-methyl sulfonamide on the left-hand side of the compounds resulted in a number of potent full agonists at the beta(3) receptor. Modification of the right-hand side of the compounds by incorporation of a free carboxylic acid resulted in a few potent human beta(3) agonists with low affinities for beta(1)- and beta(2)-ARs. N-Alkyl substitution on the 4-piperidin-1-yl-phenylamine further increased the beta(3) potency while maintaining the selectivity. For example, sulfonamide 48 is a potent full beta(3) agonist (EC(50)=0.004 microM, IA=1.0) with > 500-fold selectivity over beta(1)- and beta(2)-ARs.

Preparation of amides from acids and resin bound azides: Suppression of intramolecular lactam formation

Abstract A new method for the formation of amides on solid phase has been developed. The procedure involves the reaction between activated acids in solution and resin bound iminophosphoranes generated from the corresponding azides and tributylphosphine. The method is particularly attractive when starting from δ azido acids since amides can form without internal cyclization to the lactam.

Riluzole prodrugs for melanoma and ALS: Design, synthesis, and in vitro metabolic profiling

Riluzole (1) is an approved therapeutic for the treatment of ALS and has also demonstrated anti-melanoma activity in metabotropic glutamate GRM1 positive cell lines, a mouse xenograft assay and human clinical trials. Highly variable drug exposure following oral administration among patients, likely due to variable first pass effects from heterogeneous CYP1A2 expression, hinders its clinical use. In an effort to mitigate effects of this clearance pathway and uniformly administer riluzole at efficacious exposure levels, several classes of prodrugs of riluzole were designed, synthesized, and evaluated in multiple in vitro stability assays to predict in vivo drug levels. The optimal prodrug would possess the following profile: stability while transiting the digestive system, stability towards first pass metabolism, and metabolic lability in the plasma releasing riluzole. (S)-O-Benzyl serine derivative 9 was identified as the most promising therapeutically acceptable prodrug.

Identification of Clinically Viable Quinolinol Inhibitors of Botulinum Neurotoxin A Light Chain

Botulinum neurotoxins (BoNT) are the most potent toxins known and a significant bioterrorist threat. Few small molecule compounds have been identified that are active in cell-based or animal models, potentially due to toxin enzyme plasticity. Here we screened commercially available quinolinols, as well as synthesized hydroxyquinolines. Seventy-two compounds had IC50 values below 10 μM, with the best compound exhibiting submicromolar inhibition (IC50 = 0.8 μM). Structure–activity relationship trends showed that the enzyme tolerates various substitutions at R1 but has a clear preference for bulky aryl amide groups at R2, while methylation at R3 increased inhibitor potency. Evaluation of the most potent compounds in an ADME panel showed that these compounds possess poor solubility at pH 6.8, but display excellent solubility at low pH, suggesting that oral dosing may be possible. Our data show the potential of quinolinol compounds as BoNT therapeutics due to their good in vitro potencies and favorable ADME properties.

Discovery of 6-({4-[2-(4-tert-Butylphenyl)-1H-benzimidazol-4-yl]piperazin-1-yl}methyl)quinoxaline (WAY-207024) : An Orally Active Antagonist of the Gonadotropin Releasing Hormone Receptor (GnRH-R)

A potent, highly insoluble, GnRH antagonist with a 2-phenyl-4-piperazinylbenzimidazole template and a quinoxaline-2,3-dione pharmacophore was modified to maintain GnRH antagonist activity and improve in vitro pharmaceutical properties. Structural changes to the quinoxaline-2,3-dione portion of the molecule resulted in several structures with improved properties and culminated in the discovery of 6-([4-[2-(4-tert-butylphenyl)-1H-benzimidazol-4-yl]piperazin-1-yl] methyl)quinoxaline (WAY-207024). The compound was shown to have excellent pharmacokinetic parameters and lowered rat plasma LH levels after oral administration.

Small molecule antagonists of the gonadotropin-releasing hormone (GnRH) receptor: Structure–activity relationships of small heterocyclic groups appended to the 2-phenyl-4-piperazinyl-benzimidazole template

A previous report described the serum LH suppression pharmacology of the 2-phenyl-4-piperazinyl-benzimidazole N-ethyluracil GnRH receptor antagonist 1 following oral administration in rats. A series of small heterocycles were appended to the 2-(4-tert-butylphenyl)-4-piperazinyl-benzimidazole template in place of the N-ethyluracil. Two imidazole analogues, 32 and 41, were shown to possess substantial in vitro potency at the target receptor (hGnRH IC(50) = 7 and 18 nM, respectively) and aqueous solubility (55 and 100 microg/mL at pH 7.4, respectively). Both compounds had high oral bioavailability in rats and 32 was further examined in an orchidectomized rat model for serum LH suppression based on increased volume of distribution over 41. Serum LH levels trended lower in orchidectomized rats following oral administration of 32.