Synthesis of 3-aryl-1-[(4-phenyl-1-piperazinyl)butyl]indazole derivatives and their affinity to 5-HT1A serotonin and dopamine D1 receptors.

Eight 3-arylindazole derivatives have been synthesized and their affinity to 5-HT1A serotonin and D1 dopamine receptors was investigated by radioligand analysis. Quantitative structure-activity relationships were studied using the Free-Wilson model. An increase in affinity to dopamine D1 receptors within substituents Br > Cl > CH3 at the 5-position of the 3-arylindazole molecule has been observed. Addition of a chlorine atom to the ortho-position the of phenyl ring let to even highest activity. Replacement of the hydrogen atom at the first position of the 3-arylindazole on the (phenylpiperazine)butyl substituent caused an increase of affinity and did not change the trends of affinity dependence on structure. An inverse dependence on the structure of the studied compounds was observed for the serotonin 5-HT1A receptors. Compounds containing a methyl group at the 5-position of molecule were more active than compounds containing halogens. A chlorine atom at the ortho-position of the phenyl ring decreased affinity. Replacement of the hydrogen atom at the first position of the molecule on the phenylpiperazine)butyl substituent led to an increase in affinity. Selectivity of the studied compounds varied within a wide range. Generally, the presence of the 3-aryl-indazole fragment in the new buspirone analogues increased their affinity to dopamine receptors and reduced their affinity to serotonin receptors. Compounds containing a bromine atom in the 3-arylindazole moiety may be promising ligands for D1 receptors.