Relative importance of the saponified and unsaponified fractions of dietary olive oil on mitochondrial lipid peroxidation in rabbit heart

The effects of four edible oils on lipid peroxidation have been investigate d in rabbit heart mitochondrial membranes. The experimental oils (olive oil from the variety "picual", washed olive oil from the variety "picual": oli ve oil from the variety "arbequina" and high-oleic sunflower oil) had a sim ilar fatty-acid composition, but differed in their unsaponified fraction (p olyphenols, tocopherols, and others). The lowest hydroperoxide levels were found with picual and washed picual No differences in mitochondrial membran e thiobarbituric acid reactive substance (TBARS), alpha-tocopherol concentr ations and cytosolic antioxidant enzymes (superoxide dismutase, glutathione peroxidase, glutathione reductase and catalase) were found, whereas the Co Q(10) content correlated inversely with hydroperoxide levels in all groups. These results suggest that mitochondrial membranes with high levels of mon ounsaturated fatty acids generate low levels of lipid peroxidation. Moreove r the saponified fraction of the experimental diets proved more important i n preventing lipid peroxidation than the unsaponified fraction. Lastly, coe nzyme Q may help to prevent peroxidative stress damage in rabbit heart mito chondria. (C) 1999, Medikal Press.