ESR studies on reaction of saccharide with the free radicals generated from the xanthine oxidase/hypoxanthine system containing iron

The free radicals generated from the iron containing system of xanthine oxi dase and hypoxanthine (Fe-XO/HX) were directly detected by using spin trapp ing. It was found that not only superoxide anion (O-2(.-)) and hydroxyl rad ical (OH.), but also alkyl or alkoxyl radicals (R-.) were formed when sacch arides such as glucose, fructose slid sucrose were added into the Fe-XO/HX system. The generated amount of R-. was dependent on the kind and concentra tion of saccharides added into the Fe-XO/HX system and no R-. were detected in the absence of saccharides, indicating that there is an interaction bet ween the saccharide molecules and the free radicals generated from the Fe-X O/HX system and saccharide molecules are essential for generating R-. in th e Fe-XO/HX system, It is expected that the toxicity of R-. would be greater than of hydrophilic O-2(.-) and OH. because they are liposoluble and their lives are longer and the active sites of biomolecules are closely related with lipophilic phase, thus they can damage cells more seriously than O-2(. -) and OH.. The R-. generated from the saccharide containing Fe-XO/HX can b e effectively scavenged by selenium containing abzyme (Se-abzyme), indicati ng Se-abzyme is a promising antioxidant. (C) 2001 Federation of European Bi ochemical Societies. Published by Elsevier Science B.V. All rights reserved .