NOVEL 1-PHENYLPIPERAZINE AND 4-PHENYLPIPERIDINE DERIVATIVES AS HIGH-AFFINITY SIGMA LIGANDS

Sigma-receptors may represent an exciting new approach for the development of novel psychotherapeutic agents. Unfortunately, many of the commonly used sigma-ligands lack selectivity (e.g., many bind at phencyclidine or dopamine receptors) or suffer from other serious drawbacks. Recently, we described a series of 2-phenylaminoethanes that bind at sigma-receptors with high affinity and selectivity. Because there is evidence that 1-phenylpiperazines can structurally mimic the 2-phenylaminoethane moiety, we prepared a series of 1-phenylpiperazines and related analogues and incorporated structural features already shown to enhance the sigma-binding of the 2-phenylaminoethanes. Several of these derivatives bind at sigma-receptors with high affinity (K(i) = 1-10 nM) and lack appreciable affinity for phencyclidine and dopamine receptors. In as much as certain of these agents structurally resemble the high-affinity, but nonselective, sigma-ligand haloperidol, and because they bind with 10 times the affinity of haloperidol, we have apparently identified what appears to be the primary sigma-pharmacophore of that agent.