5-HT3 AND 5-HT4 RECEPTOR AFFINITIES OF NAPHTHO[1,2-D]THIAZOLE DERIVATIVES WITH VARIOUS BASIC SIDE-CHAINS

Several 2-piperidinyl- and 2-(piperazinyl)alkyl-substituted derivative s of 8,9-dihydronaphtho[1,2-d]thiazole and some related compounds were prepared and studied in serotonin 5-HT3 and 5-HT4 and dopamine D-2 re ceptor binding assays. The naphthothiazole group linked to N-methylpip erazine as for compound 1 led to a good 5-HT3 affinity (IC50 = 11 nM) and high selectivity versus 5-HT4 and D-2 receptors (IC50 = 1360 nM an d IC50 > 10000 nM, respectively). Replacement of the piperarine ring w ith other heterocycles lowered the 5-HT3 receptor affinity to a 310-36 00 nM range and the selectivity versus 5-HT4 receptors disappeared.