Selective inhibition of heme oxygenase-2 activity by analogs of 1-(4-chlorobenzyl)-2-(pyrrolidin-1-ylmethyl)-1H-benzimidazole (clemizole): Exploration of the effects of substituents at the N-1 position.

Several analogs based on the lead structure of 1-(4-chlorobenzyl)-2-(pyrrolidin-1-ylmethyl)-1H-benzimidazole (clemizole) were synthesized and evaluated as novel inhibitors of heme oxygenase (HO). Many of the compounds were found to be potent and highly selective for the HO-2 isozyme (constitutive), and had substantially less inhibitory activity on the HO-1 isozyme (inducible). The compounds represent the first report of highly potent and selective inhibitors of HO-2 activity, and complement our suite of selective HO-1 inhibitors. The study has revealed many candidates based on the inhibition of heme oxygenases for potentially useful pharmacological and therapeutic applications.