Synthesis of new piperazine-pyridazinone derivatives and their binding affinity toward alpha1-, alpha2-adrenergic and 5-HT1A serotoninergic receptors.

We report the design and synthesis of a new class of piperazine-pyridazinone analogs. The arylpiperazine moiety, the length of the spacer, and the terminal mol. fragment were varied to evaluate their influence in detg. the affinity of the new compds. toward the α1-adrenergic receptor (α1-AR), α2-adrenergic receptor (α2-AR), and the 5-HT1A serotoninergic receptor (5-HT1AR). Biol. data showed that most of the compds. have an α1-AR affinity in the nanomolar or subnanomolar range, while affinity toward the other two receptors was lower in most cases. However, several of the tested compds. also showed very good (in the nanomolar range) or moderate affinity toward the 5-HT1AR subtype.