Definition of a pharmacophore for partial agonists of serotonin 5-HT3 receptors

A definition of a partial agonists serotonin 5-HT3 pharmacophore was carrie d out by considering a three-dimensional model which correlates the chemica l structures of series of piperazinopyrrolothienopyrazines, piperazinopyrid opyrrolopyrazines, piperazinopyrroloquinolaxines, piperazinopyridopyrroloqu inoxalines, aminoalkyloximinopyrroloindoles, aminoalkyloximinothienopyrroli zines, and aminoalkyloxopyrrolizines with the biological affinities. The mo del is formed by five features corresponding to two hydrogen bond accepters , one aromatic ring, one hydrophobic group, and one positive ionizable site (quaternary ammonium ions). The nature of the features and the distances b etween them explain the partial agonist activities of these compounds.