Inhibition on inducible nitric oxide synthase

The scientific community has witnessed an exponential growth curve in the number of nitric oxide (NO) related publications over the last ten years. This diatomic radical is remarkably entangled (directly and indirectly) in a multitude of physiological and pathophysiological processes, including blood pressure regulation, inflammation, apoptosis, platelet adhesion, neurotransmission and host-defense mechanisms. Of the three known isozymes responsible for catalyzing the production of NO from L-arginine (L-Arg), it is the inducible form of nitric oxide synthase (iNOS) that we wish to examine here due to its involvement in a collection of diseases, including septic- and cytokine-induced shock, immune-type diabetes, rheumatoid arthritis, tissue damage, inflammation, and inflammatory bowel disease. Controlling the unregulated overproduction of NO from iNOS has been a formidable task; therapeutic intervention strategies range from preventing iNOS mRNA expression (anticytokine antibodies/receptor antagonists) to impeding NO action (NO scavengers, guanylyl cyclase inhibitors). Within these extremes lies the most conventional tactic, prohibiting NO production from iNOS with L-arginine competitive antagonists or irreversible enzyme inhibitors. This review will cover the more recent accounts gauged toward the identification and development of novel inhibitors of iNOS.