The increased generation of reactive oxygen species that occurs in the condition of obesity may be responsible for oxidative injury to erythrocyte membranes, which could lead to a decrease in tissue oxygenation. Therefore, we have looked into the effects of obesity on both indexes of oxidative damage and physical-chemical properties of erythrocyte membranes in 50 overweight or obese [25 Ͻ body mass index (BMI) Ͻ 33], normotensive, nondiabetic women and 50 age-matched lean healthy women (BMI Ͻ 25). In the obese group compared with the lean group, we found that a ) the onset of free radical-induced erythrocyte hemolysis and the ratio between reduced and oxidized glutathione were reduced, whereas the rate of free radicalinduced damage increased; b ) the n-3 fatty acid and the phospholipid contents decreased; c ) the ratio between cholesterol and phospholipids increased; and d ) the membrane fluidity decreased. These findings suggest an impairment of erythrocyte membrane physical-chemical properties in overweight and obese people as a consequence of oxidative injury that might be part of a pathogenetic mechanism responsible for obesity-related pathologies such as atherosclerosis and hypertension. -Cazzola, R., M. Rondanelli, S. Russo-Volpe, E. Ferrari, and B. Cestaro. Physiological oxidative metabolism and neutrophil activation occurring in the blood give rise to oxygen-reactive substances and other very active radical species that can irreversibly damage the surrounding macromolecules. In particular, these radicals can attack both the amino and thiol groups of proteins and the double bonds of polyunsaturated fatty acids in lipoproteins. Statistically significant correlations have been found between lipoprotein susceptibility to peroxidation, the degree of obesity, and the risk of developing cardiovascular disease (1). Because any increase in the rate of lipoprotein peroxidation not only diminishes their levels of polyunsaturated fatty acids but also consumes and reduces their antioxidant contents (vitamin E, ␤ -carotene, coenzyme Q, etc.), the consequence of these biochemical events in overweight and obese people is also a probable reduction of the "exchange rate" of both polyunsaturated fatty acids and lipophilic antioxidants that are normally transferred in the blood from the donor lipoproteins to the erythrocyte acceptor membranes. A decrease in both the degree of polyunsaturation of lipids and the antioxidant levels of the erythrocyte membrane could thus be expected, together with a decrease of both membrane fluidity and the activity of its membrane-bound enzymes. Because the erythrocyte membrane serves as a variable barrier to oxygen transport, the changes in its composition can induce cellular hypoxia in the tissue bed. Furthermore, because the size, shape, and diffusion capacity of a red blood cell depend on the structure of its membrane, alterations in membrane structure could lead to a decrease in tissue oxygenation (2). Such modifications of oxygen available in cardiovascular cells might be part ...

Athletes undergoing regular and adequate training show improved antioxidant status together with a more fluid membrane status, which could contribute to improving both peripheral resistance to insulin and all the functional metabolic interchanges in the cellular membrane.

The antioxidant properties of simple carbohydrates were studied in a chemical system. Hydroxyl radicals generated by a Fenton reaction induce damage on simple carbohydrates with a consequent free radical scavenging activity. Carbohydrate activities were measured by different methods as spin-trapping of hydroxyl radical and electron paramagnetic resonance detection and 1,1-diphenyl-2-picrylhydrazyl quenching. Carbohydrate damage was evaluated in a Fenton system by measuring the reactive substances to thiobarbituric acid, by their decreased detection with an HPLC test, and by a gas chromatographic determination of formic acid from sugar oxidation. Different intensities of damage and scavenging were found according to molecular structure, and some hyphotheses on the carbohydrate action against free radicals were attempted. The assayed disaccharides were shown to be more active toward and less damaged by hydroxyl radical than monosaccharides.