NOpiates: Novel Dual Action Neuronal Nitric Oxide Synthase Inhibitors with μ-Opioid Agonist Activity

A novel series of benzimidazole designed multiple ligands (DMLs) with activity at the neuronal nitric oxide synthase (nNOS) enzyme and the mu-opioid receptor was developed. Targeting of the structurally dissimilar heme-containing enzyme and the mu-opioid GPCR was predicated on the modulatory role of nitric oxide on mu-opioid receptor function. Structure activity relationship studies yielded lead compound 24 with excellent nNOS inhibitory activity (IC50 = 0.44 mu M), selectivity over both endothelial nitric oxide synthase (10-fold) and inducible nitric oxide synthase (125-fold), and potent mu-opioid binding affinity, K-i = 5.4 nM. The functional activity as measured in the cyclic adenosine monosphospate secondary messenger assay resulted in full agonist activity (EC50 = 0.34 mu M). This work represents a novel approach in the development of new analgesics for the treatment of pain.