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 oxidase and hypoxanthine (Fe-XO/HX) were directly detected by using spin trapping. It was found that not only superoxide anion (O(2)*-) and hydroxyl radical (OH*), but also alkyl or alkoxyl radicals (R*) were formed when saccharides such as glucose, fructose and sucrose were added into the Fe-XO/HX system. The generated amount of R* was dependent on the kind and concentration 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 between the saccharide molecules and the free radicals generated from the Fe-XO/HX system and saccharide molecules are essential for generating R* in the 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 be effectively scavenged by selenium containing abzyme (Se-abzyme), indicating Se-abzyme is a promising antioxidant.

Protection of myocardial mitochondria against oxidative damage by selenium-containing abzyme m4G3.

Selenium-containing abzyme (m4G3) was prepared and its protection of myocardial mitochondria against oxidative damage was studied using the swelling of mitochondria, quantity of lipid peroxidation products, and change in cytochrome-c oxidase activity as a measure of mitochondrial damage. The results showed that m4G3 could inhibit mitochondrial damage caused by the hypoxanthine-xanthine oxidase system in vitro. Electronic spin resonance (ESR) studies demonstrated that m4G3 could decrease the amount of free radicals generated in the damage system.