Scalable, One-Pot, Microwave-Accelerated Tandem Synthesis of Unsymmetrical Urea Derivatives

We report a facile, microwave-accelerated, one-pot tandem synthesis of unsymmetrical ureas via a Curtius rearrangement. In this method, one-pot microwave irradiation of commercially available (hetero)­aromatic acids and amines in the presence of diphenylphosphoryl azide enabled extremely rapid (1–5 min) construction of an array of unsymmetrical ureas in good to excellent yields. We demonstrate the utility of our method in the efficient, gram-scale synthesis of key biologically active compounds targeting the cannabinoid 1 and α7 nicotinic acetylcholine receptors

Expeditious Synthesis, Enantiomeric Resolution, and Enantiomer Functional Characterization of (4-(4-Bromophenyl)-3a,4,5,9b-tetrahydro‑3<i>H</i>‑cyclopenta[<i>c</i>]quinoline-8-sulfonamide (4BP-TQS): An Allosteric Agonist-Positive Allosteric Modulator of α7 Nicotinic Acetylcholine Receptors

An expeditious microwave-assisted synthesis of 4BP-TQS, its enantiomeric separation, and their functional evaluation is reported. Electrophysiological characterization in Xenopus oocytes revealed that activity exclusively resided in the (+)-enantiomer <b>1b</b> (GAT107) and (−)-enantiomer <b>1a</b> did not affect its activity when coapplied. X-ray crystallography studies revealed the absolute stereochemistry of <b>1b</b> to be 3a<i>R</i>,4<i>S</i>,9b<i>S</i>. <b>1b</b> represents the most potent ago-PAM of α7 nAChRs available to date and is considered for further in vivo evaluation

Protective effect of AM841 (0.1 mg/kg, i.p.) injected once daily for 3 days on TNBS-induced colitis in mice.

<p>Figure shows data for (A) macroscopic score, (B) MPO activity, (C) ulcer score and (D) body weight. $$$p<0.001, as compared with control animals. **p<0.01, ***p<0.001, as compared with TNBS-treated mice. Data represent means ± SEM, n = 6–8.</p

Protective effect of CB 13 after central (0.1 µg/animal, i.c.v, OD), but not peripheral (0.1 mg/kg, i.p., OD) administration for 3 days on TNBS-induced colitis in mice.

<p>Figure shows data for (A) macroscopic score, (B) MPO activity and (C) ulcer score. **p<0.01, as compared with TNBS-treated mice. Data represent means ± SEM, n = 6–8.</p

AM841 (0.1 mg/kg, i.p.) injected once daily for 7 days did not alter DSS-induced colitis in (A) CB1^-/-, (B) CB2^-/- (C) and CB1/CB2^-/- mice.

<p>Figure shows data for macroscopic score and MPO activity. $p<0.05,$$$p<0.001, as compared with control animals. Data represent means ± SEM, n = 6–8.</p

Protective effect of AM841 (0.01, 0.1 and 1 mg/kg, i.p.) injected once daily for 7 days on DSS-induced colitis in mice.

<p>Figure shows data for (A) macroscopic score, (B) MPO activity, (C) body weight, (D) representative micrographs for hematoxylin and eosin staining of colon wall sections (i, control; ii, DSS; iii, DSS+AM841 0.01 mg/kg; iv, DSS+AM841 0.1 mg/kg; v, DSS+AM841 1 mg/kg; scale bar = 100 µm) and (E) microscopic score. $$$p<0.001, as compared with control animals. *p<0.05, ***p<0.001, as compared with DSS-treated mice. Data represent means ± SEM, n = 6–8.</p

Therapeutic effect of AM841 (0.1 mg/kg, i.p.) injected once or twice daily from day 4 on DSS-induced colitis in mice.

<p>Figure shows data for (A) macroscopic score, (B) MPO activity and (C) body weight. $$p<0.01,$$$p<0.001, as compared with control animals. *p<0.05, **p<0.01, as compared with DSS-treated mice. Data represent means ± SEM, n = 6–8.</p

Chemotactic assay with murine neutrophils.

<p>AM841 (0.1–100 nM) inhibited neutrophil migration to 10 nM fMLP in a concentration-dependent manner. $p<0.05,$$$p<0.001, as compared with vehicle-treated controls. Data represent means ± SEM of 4 independent experiments performed in duplicate.</p

New Alpha9 nAChR Ligands Based on a 5‑(Quinuclidin-3-ylmethyl)-1,2,4-oxadiazole Scaffold

Several lines of evidence have indicated that nicotinic acetylcholine receptors (nAChR) that contain α9 subunits, probably in combination with α10 subunits, may be valuable targets for the management of pain associated with inflammatory diseases through a cholinergic anti-inflammatory system (CAS), which has also been associated with α7 nAChR. Both α7- and α9-containing neuronal nAChR can be pharmacologically distinguished from the high-affinity nicotinic receptors of the brain by their sensitivity to α-bungarotoxin, but in other ways, they have quite distinct pharmacological profiles. The early association of α7 with CAS led to the development of numerous new ligands, variously characterized as α7 agonists, partial agonists, or silent agonists that desensitized α7 receptors without activation. Subsequent reinvestigation of one such family of α7 ligands based on an N,N-diethyl-N′-phenylpiperazine scaffold led to the identification of potent agonists and antagonists for α9. In this paper, we characterize the α9/α10 activity of a series of compounds based on a 5-(quinuclidin-3-ylmethyl)-1,2,4-oxadiazole (QMO) scaffold and identify two new potent ligands of α9, QMO-28, an agonist, and QMO-17, an antagonist. We separated the stereoisomers of these compounds to identify the most potent agonist and discovered that only the 3R isomer of QMO-17 was an α9 antagonist, permitting an in silico model of α9 antagonism to be developed. The α9 activity of these compounds was confirmed to be potentially useful for CAS management of inflammatory pain in cell-based assays of cytokine release

Enantiospecific Allosteric Modulation of Cannabinoid 1 Receptor

The cannabinoid 1 receptor (CB1R) is one of the most widely expressed metabotropic G protein-coupled receptors in brain, and its participation in various (patho)­physiological processes has made CB1R activation a viable therapeutic modality. Adverse psychotropic effects limit the clinical utility of CB1R orthosteric agonists and have promoted the search for CB1R positive allosteric modulators (PAMs) with the promise of improved drug-like pharmacology and enhanced safety over typical CB1R agonists. In this study, we describe the synthesis and <i>in vitro</i> and <i>ex vivo</i> pharmacology of the novel allosteric CB1R modulator GAT211 (racemic) and its resolved enantiomers, GAT228 (<i>R</i>) and GAT229 (<i>S</i>). GAT211 engages CB1R allosteric site(s), enhances the binding of the orthosteric full agonist [³H]­CP55,490, and reduces the binding of the orthosteric antagonist/inverse agonist [³H]­SR141716A. GAT211 displayed both PAM and agonist activity in HEK293A and Neuro2a cells expressing human recombinant CB1R (hCB1R) and in mouse-brain membranes rich in native CB1R. GAT211 also exhibited a strong PAM effect in isolated vas deferens endogenously expressing CB1R. Each resolved and crystallized GAT211 enantiomer showed a markedly distinctive pharmacology as a CB1R allosteric modulator. In all biological systems examined, GAT211’s allosteric agonist activity resided with the <i>R-</i>(+)-enantiomer (GAT228), whereas its PAM activity resided with the <i>S</i>-(−)-enantiomer (GAT229), which lacked intrinsic activity. These results constitute the first demonstration of enantiomer-selective CB1R positive allosteric modulation and set a precedent whereby enantiomeric resolution can decisively define the molecular pharmacology of a CB1R allosteric ligand