Synthesis and characterization of NESS 0327: a novel putative antagonist of the CB1 cannabinoid receptor.
The compound N-piperidinyl-[8-chloro-1-(2,4-dichlorophenyl)-1,4,5,6-tetrahydrobenzo [6,7]cyclohepta[1,2-c]pyrazole-3-carboxamide] (NESS 0327) was synthesized and evaluated for binding affinity toward cannabinoid CB1 and CB2 receptor. NESS 0327 exhibited a stronger selectivity for CB1 receptor compared with N-piperidinyl-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (SR 141716A), showing a much higher affinity for CB1 receptor (Ki = 350 +/- 5 fM and 1.8 +/- 0.075 nM, respectively) and a higher affinity for the CB2 receptor (Ki = 21 +/- 0.5 nM and 514 +/- 30 nM, respectively). Affinity ratios demonstrated that NESS 0327 was more than 60,000-fold selective for the CB1 receptor, whereas SR 141716A only 285-fold. NESS 0327 alone did not produce concentration-dependent stimulation of guanosine 5'-O-(3-[35S]thio)-triphosphate ([35S]GTPgammaS) binding in rat cerebella membranes. Conversely, NESS 0327 antagonized [R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrolol [1,2,3-de]-1,4-benzoxazin-yl]-(1-naphthalenyl)methanone mesylate] (WIN 55,212-2)-stimulated [35S]GTPgammaS binding. In functional assay, NESS 0327 antagonized the inhibitory effects of WIN 55,212-2 on electrically evoked contractions in mouse isolated vas deferens preparations with pA2 value of 12.46 +/- 0.23. In vivo studies indicated that NESS 0327 antagonized the antinociceptive effect produced by WIN 55,212-2 (2 mg/kg s.c.) in both tail-flick (ID50 = 0.042 +/- 0.01 mg/kg i.p.) and hot-plate test (ID50 = 0.018 +/- 0.006 mg/kg i.p.). These results indicated that NESS 0327 is a novel cannabinoid antagonist with high selectivity for the cannabinoid CB1 receptor.
Ruiu
Stefania
S
Institute of Neurogenetic and Neuropharmacology, Via Boccaccio 8, 09047 Selargius, Italy. l.pani@inn.cnr.it
Pinna
Gèrard A
GA
Marchese
Giorgio
G
Mussinu
Jean-Mario
JM
Saba
Pierluigi
P
Tambaro
Simone
S
Casti
Paola
P
Vargiu
Romina
R
Pani
Luca
L
D000818:Animals; D001667:Binding, Competitive; D002186:Cannabinoids / Q000737:chemistry; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D008297:Male; D051379:Mice; D010880:Piperidines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011720:Pyrazoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D043885:Receptor, Cannabinoid, CB2; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug / Q000037:antagonists & inhibitors* / Q000378:metabolism
D002186:Cannabinoids; C469526:Cnr2 protein, rat; C475771:N-piperidinyl-(8-chloro-1-(2,4-dichlorophenyl)-1,4,5,6-tetrahydrobenzo(6,7)cyclohepta(1,2-c)pyrazole-3-carboxamide); D010880:Piperidines; D011720:Pyrazoles; D043885:Receptor, Cannabinoid, CB2; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug; D016244:Guanosine 5'-O-(3-Thiotriphosphate)