Enhancement of glutathione-dependent haemin degradation by ascorbic acid

• Published in: Biochemical pharmacology 2002-08, Vol.64 (4), p.565-572
• Main Authors: Zou, Cheng-Gang, Agar, Nihal S., Jones, Graham Lloyd
• Format: Article
• Language: English
• Subjects: Animals; Antioxidants - pharmacology; Ascorbic acid; Ascorbic Acid - pharmacology; Biological and medical sciences; Erythrocyte; Erythrocytes - drug effects; Erythrocytes - metabolism; General and cellular metabolism. Vitamins; Glutathione; Glutathione - metabolism; Haemin degradation; Hemin - metabolism; Humans; Hydrogen peroxide; Hydrogen Peroxide - metabolism; Hydrogen-Ion Concentration; In Vitro Techniques; Iron - metabolism; Medical sciences; Pharmacology. Drug treatments; Reactive Oxygen Species - metabolism; Sheep
• ISSN: 0006-2952; 1873-2968
• DOI: 10.1016/S0006-2952(02)01214-5

In the current work, we investigated the effect of ascorbic acid on GSH-mediated haemin degradation. GSH-mediated haemin degradation in the presence of ascorbic acid in phosphate-buffered saline and in erythrocyte ghosts was determined by recording absorbance at 365 and 399 nm, respectively. Generation of intracellular H 2O 2 was measured indirectly in terms of the inactivation of endogenous catalase in erythrocytes in the presence of 3-amino-1,2,4-triazole. Although ascorbic acid itself did not induce haemin degradation, it enhanced GSH-mediated haemin degradation. Experiments with catalase showed that H 2O 2 was essential in this process. The oxidation of ascorbic acid in the presence of haemin was stimulated by GSH, suggesting that ascorbic acid can alter the mechanism of H 2O 2 generation observed with GSH and haemin alone. These results suggest that enhancement of GSH-mediated haemin degradation by ascorbic acid may be due to an increase in the production of H 2O 2 generated by GSH and haemin in the absence of ascorbic acid.