Screening of NOS activity and selectivity of newly synthesized acetamidines using RP-HPLC

Nitric Oxide Synthase (NOS) inhibitors could play a powerful role in inflammatory and neurodegenerative diseases. In this work, novel acetamidine derivatives of NOS were synthesized and the inhibitor activity was evalued. To screen the activity and selectivity, the l-citrulline residue, after the enzymatic NOS assay, was derivatized with o-phthaldialdehyde/N-acetyl cysteine (OPA/NAC) and then evaluated by RP-HPLC method with fluorescence detection. All compounds did not affect the activity of endothelial and neuronal isoforms, while nine of them possessed a percentage of iNOS activity at 10μM lower than 50%, and were selected for IC50 evaluation. Among them, a compound emerged as a very potent (IC50 of 53nM) and selective iNOS inhibitor.