O-2-Acetoxymethyl-protected diazeniumdiolate-based NSAIDs (NONO-NSAIDs): Synthesis, nitric oxide release, and biological evaluation studies

A novel group of O-2-acetoxymethyl-protected diazeniumdiolate-based non-steroidal anti-inflammatory prodrugs (NONO-NSAIDs) were synthesized by esterifying the carboxylate group of aspirin, ibuprofen, or indomethacin with O-2-acetoxymethyl 1-[N-(2-hydroxyethyl)-N-methylamino]diazeniumdiolate. The resulting nitric oxide ((NO)-N-center dot)-releasing prodrugs (7-9) did not exhibit in vitro cyclooxygenase (COX) inhibitory activity against the COX-1 and COX-2 isozymes (IC50S > 100 mu M), In contrast, prodrugs 7 and 8 significantly decreased carrageenan-induced rat paw edema showing enhanced in vivo anti-inflammatory activities (ID50's = 552 and 174 mu mol/kg, respectively) relative to those of the parent NSAIDs aspirin (ID50 = 714 mu mol/kg) and ibuprofen (ID50 = 326 mu mol/kg). The rate of porcine liver esterase-mediated (NO)-N-center dot release from prodrugs 7-9 (2 mol of (NO)-N-center dot/mol of test compound in 0.6-6.5 min) was substantially higher compared to that observed without enzymatic catalysis (about 1 mol of (NO)-N-center dot/mol of test compound in 40-48 h). These incubation studies suggest that both (NO)-N-center dot and the parent NSAID would be released upon in vivo activation (hydrolysis) by esterases. Data acquired in an in vivo ulcer index (UI) assay showed that NONO-aspirin (UI = 0.8), NONO-indomethacin (UI = 1.3), and particularly NONO-ibuprofen (UI = 0) were significantly less ulcerogenic compared to the parent drugs aspirin (UI = 57), ibuprofen (UI = 46) or indomethacin (UI = 34) at equimolar doses. The release of aspirin and (NO)-N-center dot from the NONO-aspirin (7) prodrug constitutes a potentially beneficial property for the prophylactic prevention of thrombus formation and adverse cardiovascular events such as stroke and myocardial infarction. Published by Elsevier Ltd.

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