Hydroxynimesulide, the main metabolite of nimesulide, prevents hydroperoxide/hemoglobin-induced hemolysis of rat erythrocytes.
The protective effect of hydroxynimesulide, the main metabolite of the nonsteroidal antiinflammatory drug nimesulide, on red blood cells (RBCs, 0.2%; 3.5 x 10(7) cell/ml) hemolysis induced by cumene hydroperoxide (CuOOH; 50 microM) was evaluated by turbidimetric and morphological analyses. Hydroxynimesulide inhibits the CuOOH-induced hemolysis in a dose dependent fashion: the protective effect, calculated after 150 min incubation (100% hemolysis in the controls), starts at 1 micron (% hemolysis 85.2 +/- 3.4%) and increases at the higher concentrations (63.5 +/- 3.9% at 5 microM; 43.5 +/- 6.3% at 10 microM; and, 14.5 +/- 4.3% at 20 microM). In addition, in the samples protected with 10 microM and 20 microM, there is a significant delay (30 and 60 min) in the onset of the hemolytic response. Inhibition of hemolysis is the result of protection of RBC membrane integrity, both on lipid (cis-Parinaric acid fluorescence quenching was delayed by 53 +/- 10 sec vs. the controls at 1 micron, by 115 +/- 15 sec at 5 microM, with a lag phase of 240 +/C- 18 sec at 10 microM) and protein constituents, as determined by SDS-PAGE electrophoresis. In hemolysis experiments, the efficacy of hydroxynimesulide is comparable to that of alpha-tocopherol and a cooperative interaction between hydroxynimesulide and alpha-tocopherol (both at 10 microM) has been observed. These results indicate that hydroxynimesulide protects RBC membranes by directly quenching reactive oxygen species generated by hemoglobin/peroxide interaction. Evidence for a direct radical scavenging intervention of the metabolite comes from HPLC studies, which demonstrate a time-dependent consumption of hydroxynimesulide, with the concomitant formation of two main reaction (addition/oxidation) products.
Maffei Facino
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Istituto Chimico Farmaceutico Tossicologico, Milan, Italy. Roberto.MaffeiFacino@unimi.it
Carini
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Aldini
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Calloni
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D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism / Q000494:pharmacology*; D001555:Benzene Derivatives / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000633:toxicity*; D002851:Chromatography, High Pressure Liquid; D004347:Drug Interactions; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism; D004912:Erythrocytes / Q000187:drug effects*; D006454:Hemoglobins / Q000378:metabolism / Q000633:toxicity*; D006461:Hemolysis / Q000187:drug effects*; D008297:Male; D008565:Membrane Proteins / Q000097:blood; D010084:Oxidation-Reduction; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D013449:Sulfonamides / Q000378:metabolism* / Q000494:pharmacology*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D001555:Benzene Derivatives; D006454:Hemoglobins; D008565:Membrane Proteins; D017382:Reactive Oxygen Species; D013449:Sulfonamides; C055891:4-nitro-2-(4'-hydroxyphenoxy)methanesulfonanilide; C007164:cumene hydroperoxide; C012655:nimesulide