5-(Sulfonyl)oxy-tryptamines and ethylamino side chain restricted derivatives. Structure-affinity relationships for h5-HT1B and h5-HT1D receptors

Systematic in vivo screening of a series of 1-propyl-4-arylpiperidines against dopaminergic and serotonergic properties in rat brain: a scaffold-jumping approach

A series of 1-propyl-4-arylpiperidines were synthesized and their effects on the dopaminergic and serotonergic systems tested in vivo and in vitro. Scaffold jumping among five- and six-membered bicyclic aryl rings attached to the piperidine ring had a marked impact on these effects. Potent and selective dopamine D(2) receptor antagonists were generated from 3-indoles, 3-benzoisoxazoles, 3-benzimidazol-2-one, and 3-benzothiophenes. In contrast, 3-benzofuran was a potent and selective inhibitor of monoamine oxidase (MAO) A. The effects of the synthesized compounds on 3,4-dihydroxyphenylacetic acid (DOPAC) levels correlated very well with their affinity for dopamine D(2) receptors and MAO A. In the 4-arylpiperidine series, the most promising compound for development was the 6-chloro-3-(1-propyl-4-piperidyl)-1H-benzimidazol-2-one (19), which displayed typical dopamine D(2) receptor antagonist properties in vivo but produced only a partial reduction on spontaneous locomotor activity. This indicates that the compound may have a lower propensity to induce parkinsonism in patients.

New (sulfonyloxy)piperazinyldibenzazepines as potential atypical antipsychotics: chemistry and pharmacological evaluation

A series of 2- or 8-trifluoromethylsulfonyloxy (TfO) and 2- or 8-methylsulfonyloxy (MsO) 11-piperazinyldibenzodiazepines, -oxazepines, and -thiazepines were synthesized and evaluated in pharmacological models for their potential clozapine-like properties. In receptor binding assays, the 2-TfO analogues (18a, GMC2-83; 24, GMC3-06; and previously reported GMC1-169, 9a) of the dibenzazepines have profiles comparable to that of clozapine, acting on a variety of CNS receptors except they lack M1 receptor affinity. Introduction of 2-TfO to clozapine leads to compound 9e (GMC61-39) which has a similar binding profile as that of clozapine including having M1 receptor affinity. Interestingly, the MsO analogues, as well as the 8-TfO analogues, have no or weak dopaminergic and serotonergic affinities, but all 8-sulfonyloxy analogues do have M1 affinities. In behavioral studies performed to indicate the potential antipsychotic efficacy and the propensity to induce EPS, 2-TfO analogues blocked effectively the apomorphine-induced climbing in mice in a dose-dependent manner with ED50 values (mg/kg) of 2.1 sc for 9a, 1.3 po for 18a, 2.6 sc for 24, and 8.2 sc for 9e. On the other hand, they showed a clear dose separation with regard to their ED50 values (mg/kg) for indicating catalepsy in rats (>44 sc for 9a, 28 po for 18a, 30 sc for 24, and >50 sc for 9e, respectively), thus implicating a more favorable therapeutic ratio (K/A, ED50 climbing/ED50 catalepsy) in comparison with typical neuroleptics such as haloperidol and isoclozapine. Furthermore, compound 18a was also demonstrated to be an orally potent DA antagonist with an ED50 value of 0.7 mg/kg po in the ex vivo L-DOPA accumulation model. The present study contributes to the SAR of 11-piperazinyldibenzazepines, and the 2-TfO analogues of 11-piperazinyldibenzazepines are promising candidates as clozapine-like atypical antipsychotics with low propensity to induce EPS.