Conformationally Constrained Analogues of N-(Piperidinyl)-5-(4-Chlorophenyl)-1-(2,4- Dichlorophenyl)-4-Methyl-1H-Pyrazole-3-Carboxamide (SR141716): Design, Synthesis, Computational Analysis, And Biological Evaluations

Abstract

Structure-activity relationships (SARs) of 1 (SR141716) have been extensively documented, however, the conformational properties of this class have received less attention. In an attempt to better understand ligand conformations optimal for receptor recognition, we have designed and synthesized a number of derivatives of 1, including a four-carbon-bridged molecule (11), to constrain rotation of the diaryl rings. Computational analysis of 11 indicates approximately 20 kcal/mol energy barrier for rotation of the two aryl rings. NMR studies have determined the energy barrier to be approximately 18 kcal/mol and suggested atropisomers could exist. Receptor binding and functional studies with these compounds displayed reduced affinity and potency when compared to 1. This indicates that our structural modifications either constrain the ring systems in a suboptimal orientation for receptor interaction or the introduction of steric bulk leads to disfavored steric interactions with the receptor, and/or the relatively modest alterations in the molecular electrostatic potentials results in disfavored Coulombic interactions.

A synthetic cannabinoid, CP55940, inhibits lipopolysaccharide-induced cytokine mRNA expression in a cannabinoid receptor-independent mechanism in rat cerebellar granule cells

“…Next, we examined whether the inhibitory effect of CP55940 on LPS‐induced cytokine expression in CGCs was mediated by the CB 1 receptor. For this purpose, cells were treated with NESS0327, a potent CB 1 and CB 2 receptor antagonist [33,34] . NESS0327 (3 µ m ) did not reverse the inhibition of cytokine mRNA expression induced by CP55940 (Figure 5a–c), suggesting that CP55940 inhibited LPS‐induced cytokine mRNA expression in a manner independent of CB 1 and CB 2 .…”

Endocannabinoid tone versus constitutive activity of cannabinoid receptors

“…Support for the former conclusion was provided by the finding that rimonabant inhibited basal [ 35 S]GTPγS binding in brain membranes from CB 1 knock‐out mice (Breivogel et al ., 2001). Similar differences in potencies of novel CB 1 antagonists as neutral antagonists versus inverse agonists have also been reported in more recent studies (Thomas et al ., 2005; Zhang et al ., 2008). Moreover, rimonabant displays a similarly low potency in producing inverse agonist effects on cAMP production in brain membranes (Mato et al ., 2002).…”

Synthesis and Biological Evaluation of Bivalent Ligands for the Cannabinoid 1 Receptor

“…The methods used for performing binding assays in transfected cells expressing human CB1 or CB2 receptors were similar to those previously described for rat brain membrane preparations. 25, 35 Binding was initiated with the addition of 40 μg of cell membrane proteins to assay tubes containing [ 3 H]CP-55,940 (ca. 130 Ci/mmol) or [ 3 H]- 1 (ca.…”