Ascorbate-dependent formation of hydroxyl radicals in the presence of iron chelates.
The autoxidation of L-ascorbate on incubation in saline phosphate buffer (pH 7.4) is accompanied by hydroxyl radical (.OH) generation. The metal chelator EDTA showed significant inhibition of ascorbate autoxidation and ascorbate-dependent .OH release. On the other hand, Fe2+ (EDTA) greatly augmented both ascorbate autoxidation and ascorbate-dependent .OH production. The biological iron chelating compounds such as ATP, ADP, citrate and pyrophosphate suppressed both ascorbate autoxidation and ascorbate-mediated .OH production, thereby indicating that these compounds suppress the activating effect of iron. Ascorbate autoxidation and ascorbate-dependent .OH formation, stimulated by Fe2+ (EDTA) were significantly inhibited by .OH scavengers, namely mannitol, thiourea and sodium formate, as well as by catalase and to a lesser extent by bovine serum albumin, superoxide dismutase (native and heat denatured) and heat denatured catalase.
Prabhu
H R
HR
Department of Biochemistry, Kasturba Medical College, Mangalore.
Krishnamurthy
S
S
D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D001205:Ascorbic Acid / Q000737:chemistry*; D002374:Catalase / Q000378:metabolism; D004492:Edetic Acid; D005296:Ferrous Compounds; D005561:Formates; D016166:Free Radical Scavengers; D006639:Histidine; D017665:Hydroxyl Radical; D007502:Iron Chelating Agents; D007700:Kinetics; D008353:Mannitol; D010084:Oxidation-Reduction; D013482:Superoxide Dismutase / Q000378:metabolism; D013890:Thiourea
D005296:Ferrous Compounds; D005561:Formates; D016166:Free Radical Scavengers; D007502:Iron Chelating Agents; C055526:Fe(II)-EDTA; D017665:Hydroxyl Radical; D008353:Mannitol; D006639:Histidine; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D004492:Edetic Acid; D002374:Catalase; D013482:Superoxide Dismutase; D013890:Thiourea; D001205:Ascorbic Acid