In Vitro Chemotoxicity of Aspirin Metabolites on G6pd-Normal and G6pd-Deficient Human Erythrocytes

The effects of aspirin metabolites on reduced glutathione (GSH), methemoglobin (MHb) and MHb reduction were studied in erythrocytes from glucose-6-phosphate dehydrogenase-normal (G6PD-normal) and G6PD-deficient volunteers. The aspirin metabolites used in various concentrations were sodium salts of salicylic acid (Na-SA), salicyluric acid (Na-SU) and gentisic acid (Na-GA). While Na-GA decreased GSH level appreciably, only slight lowering of GSH level was observed with Na-SA and Na-SU. Similarly, Na-GA, even at low concentration of 0.03 mM, showed effect on MHb formation and the effect was increased significantly with increasing concentration. But, no effect on MHb formation was observed with Na-SA and Na-SU. However, Na-SA and Na-SU showed significant inhibitory effects on the reduction of MHb which was far more prominent with Na-GA. These findings led to the notion that neither SA nor SU can produce any appreciable oxidative damage to Hb, while GA is the main metabolite to effect oxidation of Hb. However, SA and SU showed their ability to inhibit MHb reduction and can interfere with the regeneration of Hb. These effects of aspirin metabolites were more pronounced in G6PD-deficient erythrocytes as compared to G6PD-normal erythrocytes implicating the importance of G6PD in aspirin toxicity. Thus, the present study indicates that aspirin metabolites act at different sites of GSH and Hb metabolic pathways, ultimately producing increased erythrocyte fragility with consequent hemolysis. However, the fragility of cellular plasma membrane is dependent on the integrity of the physiological antioxidant systems. Therefore, further studies are warranted in these areas to understand fully the mechanisms of toxicity of aspirin metabolites in human erythrocytes.