CONICET | Buscador de Institutos y Recursos Humanos

Oxidative damage to lipids depends on the nature of the oxidant, the type of lipid, and the severity of the oxidation. Since a variety of stable products are formed, several assays have been developed over the years to assess these products in order to evaluate lipid peroxidation. The most currently used assay is the determination of malondialdehyde (MDA) formation with the thiobarbituric acid reactive substances test (TBARS). However, this compound is one of the many end products of lipid oxidation and its reaction with thiobarbituric acid can be reproduced by other biological compounds. Electron paramagnetic resonance (EPR) spectroscopy has shown the capacity of detecting, in the presence of exogenous traps, the presence of the lipid radical formed during peroxidation, by yielding unique and stable products. Thus, even though EPR detection of lipid radicals could be considered a finger-print of radical presence, spin trapping studies cannot really distinguish among peroxyl (ROO?), alcohoxyl (RO?) and alkyl (R?) adducts owing to the similarity of the corresponding coupling constants. We used EPR technology to detect lipid radicals in in vitro systems to characterize the antioxidant capacity of plant extracts, and the oxidative damage to lipids in different photosynthetic systems, such as green algae undergoing oxidative stress conditions. Among stress situations, lipid peroxidation was evaluated by EPR in wheat leaves subjected to drought and watering, soybean cotyledons during natural senescence, and sorghum embryonic axes during imbibition. Also, the effect of NO donors on lipid radical content in sorghum embryonic axes, and on soybean chloroplasts membranes was assessed. Thus, this reliable method can be successfully adapted to study biological implications of oxidative damage to lipids in different types of biological materials, and specially in photosynthetic tissues.