Synthesis of arylpiperazines with a terminal naphthothiazole group and their evaluation on 5-HT, DA and a receptor

On the role of polarizability in QSAR

The polarizability of a molecule, an important physical property, is currently attracting our attention particularly in the area of QSAR for chemical-biological interactions. In this report, the polarizability effects on ligand-substrate interactions has been discussed in terms of NVE (number of valence electrons) using additive values for valence electrons and the formulation of a total number of 51 QSAR. The QSAR model can be illustrated by Eq. I. log 1/C = a(NVE) +/- constant

Synthesis and pharmacological evaluation of aryl/heteroaryl piperazinyl alkyl benzotriazoles as ligands for some serotonin and dopamine receptor subtypes

Thirteen [(aryl/heteroaryl-piperazinyl)alkyl]benzotriazoles were prepared as potential trazodone- and buspirone-like drugs. The synthesized compounds displayed from moderate to good affinity to the serotonin 5-HT1A receptor and only modest or poor affinity to the dopamine D2 receptor, similar to buspirone. The introduction of substituents on the benzotriazole ring did not improve the affinity to the 5-HT1A receptor, compared to the previously described unsubstituted derivatives. In a general pharmacological screening, which concerned only three of these compounds so far (5, 7 and 13), several in vitro and in vivo activities were observed. The guinea pig ileum contractions, induced either electrically or by several agonists, were strongly inhibited; at higher concentrations also the spontaneous tone of the guinea pig trachea was reduced. Compound 13 exhibited good analgesic activity in mice in the formalin-induced algesia and in the writhing test. The same at 30 mg kg(-1) p.o. also displayed antihypertensive activity probably related to calcium channel blockade and adrenergic alpha1 antagonism. In binding assays, 13 showed a IC50 = 580 nM for displacing [3H]prazosin from alpha1 receptor. Finally, compound 5 (and, to a minor extent, compound 13) protected mice against potassium cyanide induced hypoxia.

2-[4-[3-(4-aryl/heteroaryl-1-piperazinyl)propoxy]phenyl]-2H- benzotriazoles and their N-oxides as ligands for serotonin and dopamine receptors

A small set of 2-{4-[3-(4-aryl/heteroaryl-piperazinyl)propoxy]phenyl}-2H-benzo tri azoles and corresponding N-oxides were prepared. The synthesized compounds were able to bind on some serotonin (5-HT1A, 5-HT2A) and dopamine (D2, D3) receptors, while displaying poor or no affinity for 5-HT1B, 5-HT2C, 5-HT3, and 5-HT4 subtypes. The strong contribution of the N-oxide function for the binding on 5-HT1A, D2 and D3 receptors is noteworthy. For 2-{4-[3-[4-(2-methoxyphenyl)-1-piperazinyl]propoxy]phenyl}-2H-benzotr iazole- 1-oxide (4b), the binding constants (Ki) were 11.9 (5-HT1A) and 10.5 nM (D3). In a general pharmacological screening, the 2-{4-[3-(4-phenyl-1-piperazinyl)propoxy]phenyl}-2H-benzotriazole (3a) exhibited only very weak activities, with the exception of protecting mice from cyanide-induced hypoxia.

N-[2-[4-(4-Chlorophenyl)piperazin-1-yl]ethyl]-3-methoxybenzamide: a potent and selective dopamine D4 ligand

A series of new 1-aryl-4-alkylpiperazines containing a terminal benzamide fragment or a tetralin-1-yl nucleus on the alkyl chain were synthesized and tested for binding at cloned human dopamine D4 and D2 receptor subtypes. A SAFIR (structure-affinity relationship) study on this series is herein discussed. The most relevant D4 receptor affinities were displayed by N-[omega-[4-arylpiperazin-1-yl]alkyl]-methoxybenzamides (compounds 5, 16-20), their IC50 values ranging between 0.057 and 7.8 nM. Among these, N-[2-[4-(4-chlorophenyl)piperazin-1-yl]ethyl]-3-methoxybenzamide (17) emerged since it exhibited very high affinity for dopamine D4 receptor (IC50 = 0.057 nM) with selectivity of >10 000 for the D4 versus the D2 receptor; compound 17 was also selective versus serotonin 5-HT1A and adrenergic alpha1 receptors.