Glucose: a role as a free radical scavenger in biological systems

Recent observations indicate that OH . may be important in the microbicidal capacity of phagocytic cells, in prostaglandin metabolism, and as a mediator of inflammation. Although glucose is a weak hydroxyl scavenger, it occurs in high concentrations in biological systems. We therefore studied the capacity of glucose to scavenge OH . in biological systems known to generate this reactive oxygen species. Our experiments used a specific assay for the detection of OH .. We measured 14CO2 released during the oxidation of 14C-benzoic acid. We have previously demonstrated that benzoic acid is oxidized as a consequence of OH . in the following systems: the enzyme system xanthine-xanthine oxidase, zymosan-stimulated granulocytes, and arachidonic acid-stimulated platelets as a consequence of the lipoxygenase pathway. In all three systems the oxidation of benzoic acid was inversely proportional to the concentration of glucose in the assays. Also, platelets incubated with arachidonic acid and a high concentration of glucose increased HETE production, an effect predicted by the capacity of glucose to act as an OH . scavenger. Our results indicate that glucose acts as a scavenger of OH . in physiological concentrations and therefore may serve an antioxidant role in biological systems. In addition, the capacity of glucose to act as an OH . scavenger may explain some of the defects seen in patients with diabetes mellitus.