Synthesis and D(2)-like binding affinity of new derivatives of N-(1-ethyl-2-pyrrolidinylmethyl)-4,5-dihydro-1H-benzo[g]indole-3-carboxamide and related 4H-[1]benzothiopyrano[4,3-b]pyrrole and 5,6-dihydro-4H-benzo[6,7]cyclohepta[b]pyrrole-3-carboxamide analogues

Various new derivatives and structural analogues of N-(1-ethyl-2-pyrrolidinylmethyl)-4,5-dihydro-1H-benzo[g]indole-3-carboxamide (2a), a representative term of a series of 2-aminomethylpyrrolidinyl derived 4,5-dihydrobenzo[g]indolcarboxamides with good D(2)-like affinity, were synthesized and evaluated for their ability to bind to dopamine D(2)-like receptors in vitro. The structural contribution to D(2)-like receptor binding of the 4,5-dihydrobenzo[g]indole portion of the molecule was examined. From these studies, compound 2k, 2-chloro-N-(1-ethyl-2-pyrrolidinylmethyl)-5,6-dihydro-4H-benzo[6,7]cyclohepta[b]pyrrole-3-carboxamide, was found to possess a potent affinity for D(2)-like receptors. Behavioural tests in rats have shown that this compound reduces the hyperactivity induced by amphetamine, a property shared by all antipsychotic drugs, at a dose which failed to induce catalepsy, an effect which is predictive of extrapyramidal side effects in humans. The other compounds demonstrated moderate (2c, 2h, and 2j) or no affinity for D(2)-like receptors.     

Tricyclic pyrazoles. Part 2: Synthesis and biological evaluation of novel 4,5-dihydro-1H-benzo[g]indazole-based ligands for cannabinoid receptors

A series of 4,5-dihydro-1H-benzo[g]indazole-3-carboxamides (2a-k) as analogues of the previously reported CB(2) ligands 6-chloro- and 6-methyl-1-(2',4'-dichlorophenyl)-N-piperidin-1-yl-1,4-dihydroindeno[1,2-c]pyrazole-3-carboxamides (1a,b) was synthesized and their affinity and selectivity towards CB(1) and CB(2) receptors were evaluated. Several of the new compounds (2a,b,c,d and i) exhibited CB(1) affinity in the nanomolar range with moderate or negligible affinity towards CB(2) receptors. Compounds 2a and c increased intestinal propulsion in mouse. Their pro-kinetic effects were reversed by the reference CB agonist CP-55,940. Consequently, in vivo CB(1) antagonistic activity was highlighted for these compounds.     

Tricyclic pyrazoles. Part 1: synthesis and biological evaluation of novel 1,4-dihydroindeno[1,2-c]pyrazol-based ligands for CB1and CB2 cannabinoid receptors

Cannabinoids receptors, cellular elements of the endocannabinoid system, have been the focus of extensive studies because of their potential functional role in several important physiological and pathological processes. To further evaluate the properties of CB receptors, especially CB(1) and CB(2) subtypes, we have designed, using SR141716A as a benchmark, a new series of rigid 1-aryl-1,4-dihydroindeno[1,2-c]pyrazole-3-carboxamides. Compounds 1 were synthesized from substituted 1-aryl-1,4-dihydroindeno[1,2-c]pyrazole-3-carboxylic acids and requisite amines. The various analogues were assayed for binding both to the brain and peripheral cannabinoid receptors (CB(1) and CB(2)). Seven of the new compounds displayed very high in vitro CB(2) binding affinities, especially 1a, 1b, 1c, 1e, 1g, 1h and 1j which showed K(i) values of 0.34, 0.225, 0.27, 0.23, 0.385, 0.037 and 0.9 nM, respectively. Compounds 1a, 1b, 1c and 1h showed the highest selectivity for CB(2) receptor with K(i)(CB(1)) to K(i)(CB(2)) ratios of 6029, 5635, 5814 and 9810, respectively. Noticeably, 1h exhibited the highest affinity and selectivity for CB(2) receptors.     

N-3(9)-arylpropenyl-N-9(3)-propionyl-3,9-diazabicyclo[3.3.1]nonanes as mu-opioid receptor agonists. Effects on mu-affinity of arylalkenyl chain modifications

Two series of N-3-arylpropenyl-N-9-propionyl-3,9-diazabicyclo[3.3.1]nonanes (1b-j) and of the reverted N-3-propionyl-N-9-arylpropenyl isomers (2b-j) as analogues of the previously reported analgesic N-3(9)-cinnamyl-N-9(3)-propionyl-3,9-diazabicyclo[3.3.1]nonanes (DBN) (1a, 2a) were synthesised and their affinity and selectivity towards opioid mu-, delta- and kappa-receptors were evaluated. Several compounds (1e,i,j-2d,e,f,g,j) exhibited a mu-affinity in the low nanomolar range with moderate or negligible affinity towards delta- and kappa-receptors. The representative term N-9-(3,3-diphenylprop-2-enyl)-N-3-propionyl-DBN (2d) displayed in vivo (mouse) a potent analgesic effect (ED(50) 3.88 mg/kg ip) which favourably compared with that of morphine (ED(50) 5 mg/kg ip). In addition, 2d produced in mice tolerance after a period twice as long with morphine.