Diazen-1-ium-1,2-diolated nitric oxide donor ester prodrugs of 1-(4-methanesulfonylphenyl)-5-aryl-1H-pyrazol-3-carboxylic acids: Synthesis, nitric oxide release studies and anti-inflammatory activities

A new group of hybrid nitric oxide-releasing anti-inflammatory drugs (NONO-coxibs) wherein an O2-acetoxymethyl-1-(N-ethyl-N-methylamino)diazen-1-ium-1,2-diolate (11a–c) NO-donor moiety is attached directly to the carboxylic acid group of 1-(4-methanesulfonylphenyl)-5-aryl-1H-pyrazol-3-carboxylic acids were synthesized. The diazen-1-ium-1,2-diolate compounds 11a–c all released a low amount of NO upon incubation with phosphate buffer (PBS) at pH 7.4 (7.7–9.3% range). In comparison, the percentage of NO released was significantly higher (67.5–73.6% of the theoretical maximal release of two molecules of NO/molecule of the parent hybrid ester prodrug) when the diazen-1-ium-1,2-diolate ester prodrugs were incubated in the presence of rat serum. These incubation studies suggest that both NO and the anti-inflammatory 1-(4-methanesulfonylphenyl)-5-(4-H, 4-F or 4-Me-phenyl)-1H-pyrazol-3-carboxylic acid (9a–c) would be released from the parent NONO-coxib upon in vivo cleavage by non-specific serum esterases. The 1-(4-methanesulfonylphenyl)-5-(4-H, 4-F or 4-Me-phenyl)-1H-pyrazol-3-carboxylic acids (9a–c) exhibited AI activities (ID50 = 85.2–104.4 mg/kg po range) between that exhibited by the reference drugs aspirin (ID50 = 128.7 mg/kg po) and celecoxib (ID50 = 10.8 mg/kg po). Hybrid ester anti-inflammatory/NO-donor prodrugs (NONO-coxibs) offers a potential drug design concept targeted toward the development of anti-inflammatory drugs that are devoid of adverse ulcerogenic and/or cardiovascular effects.

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