Synthesis and SAR studies of novel benzodiazepinedione-based inhibitors of Clostridium difficile (C. difficile) toxin B (TcdB).

Synthesis and structure-activity relationships (SAR) of a novel series of benzodiazepinedione-based inhibitors of Clostridium difficile toxin B (TcdB) are described. Compounds demonstrating low nanomolar affinity for TcdB, and which possess improved stability in mouse plasma vs. earlier compounds from this series, have been identified. Optimized compound 11d demonstrates a good pharmacokinetic (PK) profile in mouse and hamster and is efficacious in a hamster survival model of Clostridium difficile infection.

Treatment of Clostridium difficile Infection with a Small-Molecule Inhibitor of Toxin UDP-Glucose Hydrolysis Activity.

Clostridium difficile infection (CDI) is the leading cause of hospital-acquired infectious diarrhea, with significant morbidity, mortality, and associated health care costs. The major risk factor for CDI is antimicrobial therapy, which disrupts the normal gut microbiota and allows C. difficile to flourish. Treatment of CDI with antimicrobials is generally effective in the short term, but recurrent infections are frequent and problematic, indicating that improved treatment options are necessary. Symptoms of disease are largely due to two homologous toxins, TcdA and TcdB, which are glucosyltransferases that inhibit host Rho GTPases. As the normal gut microbiota is an important component of resistance to CDI, our goal was to develop an effective nonantimicrobial therapy. Here, we report a highly potent small-molecule inhibitor (VB-82252) of TcdA and TcdB. This compound inhibits the UDP-glucose hydrolysis activity of TcdB and protects cells from intoxication after challenge with either toxin. Oral dosing of the inhibitor prevented inflammation in a murine intrarectal toxin challenge model. In a murine model of recurrent CDI, the inhibitor reduced weight loss and gut inflammation during acute disease and did not cause the recurrent disease that was observed with vancomycin treatment. Lastly, the inhibitor demonstrated efficacy similar to that of vancomycin in a hamster disease model. Overall, these results demonstrate that small-molecule inhibition of C. difficile toxin UDP-glucose hydrolysis activity is a promising nonantimicrobial approach to the treatment of CDI.

Identification and initial optimization of inhibitors of Clostridium difficile (C. difficile) toxin B (TcdB).

The discovery, synthesis and preliminary structure-activity relationship (SAR) of a novel class of inhibitors of Clostridium difficile (C. difficile) toxin B (TcdB) is described. A high throughput screening (HTS) campaign resulted in the identification of moderately active screening hits 1-5 the most potent of which was compound 1 (IC50 = 0.77 µM). In silico docking of an early analog offered suggestions for structural modification which resulted in the design and synthesis of highly potent analogs 13j(IC50 = 1 nM) and 13 l(IC50 = 7 nM) which were chosen as leads for further optimization.

Synthesis and structure-activity relationship of a novel series of heterocyclic sulfonamide gamma-secretase inhibitors.

gamma-Secretase inhibitors have been shown to reduce the production of beta-amyloid, a component of the plaques that are found in brains of patients with Alzheimer's disease. A novel series of heterocyclic sulfonamide gamma-secretase inhibitors that reduce beta-amyloid levels in cells is reported. Several examples of compounds within this series demonstrate a higher propensity to inhibit the processing of amyloid precursor protein compared to Notch, an alternative gamma-secretase substrate.

Identification and SAR of squarate inhibitors of mitogen activated protein kinase-activated protein kinase 2 (MK-2).

A novel series of inhibitors for mitogen activated protein kinase-activated protein kinase 2 (MK-2) are reported. These squarate based inhibitors were identified via a high-throughput screen. An MK2 co-structure with the starting ligand was obtained and a structure based approach was followed to optimize potency and selectivity.

Antiobesity-like effects of the 5-HT2C receptor agonist WAY-161503.

WAY-161503 ((4aR)-8,9-dichloro-2,3,4,4a-tetrahydro-1H-pyrazino[1,2-a]quinoxalin-5(6H)-one), a 5-HT(2B/C) receptor agonist, was characterized in vitro using stable Chinese hamster ovary cell lines expressing each of the human 5-HT2 receptors and in vivo in animal models of obesity. WAY-161503 displaced both agonist ([125I]2,5-dimethoxy-4-iodoamphetamine (DOI)) and antagonist ([3H]mesulergine) radioligand binding to the human 5-HT2C receptor with derived Ki values of 3.3 +/- 0.9 and 32 +/- 6 nM, respectively. Relative to 5-HT2C receptor binding, WAY-161503 was approximately 6-fold less potent at human 5-HT2A receptors ([125I]DOI) with a derived Ki value of 18 nM and 20-fold less potent at human 5-HT2B receptors ([3H]5-HT) with a derived Ki value of 60 nM. In functional studies, WAY-161503 was a full agonist in stimulating 5-HT2C-receptor-coupled [3H]inositol phosphate (IP) formation and calcium mobilization with EC50 values of 8.5 nM and 0.8 nM, respectively. WAY-161503 was also a 5-HT2B agonist (EC50s of 6.9 and 1.8 nM for IP and calcium, respectively). In IP studies, WAY-161503 was a weak 5-HT(2A) partial agonist (EC50, 802 nM) yet potently stimulated calcium mobilization (EC50, 7 nM) in 5-HT2A receptor-expressing cells. Functionally, WAY-161503 also stimulated the phospholipase A2-coupled arachidonic acid release in 5-HT2C receptor expressing cells albeit with lower potency (EC50, 38 nM) and efficacy (Emax, 77%) compared with activation of the PLC pathway. In vivo, WAY-161503 produced dose-dependent decreases in 2-h food intake in 24 h fasted normal Sprague-Dawley rats, diet-induced obese mice, and obese Zuker rats with ED50 values of 1.9 mg/kg, 6.8 mg/kg, and 0.73 mg/kg, respectively. The reduction in food intake in normal Sprague-Dawley rats was reversed by administration of the 5-HT2C receptor antagonist SB-242084. Following chronic administration (10 days) in growing Sprague-Dawley rats, WAY-161503 decreased food intake and attenuated body weight gain. Finally, following chronic administration (15 days) of WAY-161503 to obese Zuker rats, the rats maintained a 30% decrease in food intake over the 15-day period combined with a 25 g decrease in body weight relative to vehicle-treated controls demonstrating a lack of tolerance to its anorectic effects.

Cycloalkyl[b][1,4]benzodiazepinoindoles are agonists at the human 5-HT2C receptor.

Evaluation of selected compounds from our Corporate Compound Library in a human 5-HT(2C) receptor binding assay led to the discovery of WAY-629, a cyclohexyl[b][1,4]benzodiazepinoindole (K(i) 56 nM, E(max) 90%), which is selective for the 5-HT(2C) receptor versus other serotonin receptor subtypes, and dopamine, histamine, adrenergic, and muscarinic receptors. In addition, WAY-629 was active in vivo in a rat model of feeding behavior. An SAR study based on WAY-629 led to compound 11 (K(i) 13 nM, E(max) 102%).