Synthesis and pharmacological evaluation of imidazoline sites I1 and I2 selective ligands Original Research Article

Several series of 2-aryl or heterocyclic-imidazoline compounds have been prepared and evaluated in vitro as imidazoline sites (I1 and I2) and α-adrenergic (α1 and α2) receptor ligands. Their pKi values indicate that linkage of the imidazoline moiety at the 2-position with an aromatic substituent dramatically decreases α-adrenergic affinity. I1 sites are more accessible by phenyl imidazolines substituted by a methyl or a methoxy group at the ortho or meta position. Indeed, 2-(2′-methoxyphenyl)-imidazoline (17) is one of the best I1 ligands ever reported (pKi=8.53 and I1/I2>3388). On the other hand, I2 selectivity increases in the presence of a methyl group in the para position. The original compound, 2-(3′-fluoro-4′-tolyl)-imidazoline (31) is a new potent ligand for the I2 sites with high selectivity (pKi=8.53 and I2/I1>3388).