Suplementação com ácido linoléico conjugado: Estabilidade oxidativa dos suplementos e correlações com conteúdo dos lípides totais hepáticos e indicadores da oxidação dos lípides biológicos de ratos Wistar

Abstract

Objective: The claimed action of conjugated linoleic acid as an antioxidant is unexpected and unclear, in view of its chemical structure - a conjugated diene, i.e., a fatty acid in its initial stage of autoxidation. Indeed, it can be speculated that it could act as a pro-oxidant, increasing oxidative stress in biological systems, nevertheless it has carbon-carbon bonds in the trans configuration. The objective of the present work was to evaluate the oxidative stability of commercial mixtures, and to investigate a possible correlation between conjugated linoleic acid supplementation and total hepatic lipid content, as well as some lipid oxidation indicators in rats. Methods: A biological assay was done with thirty rats divided into three groups (n=10) characterized as control and supplemented with the commercial mixtures AdvantEdge® and One®. The mixtures were administered in the concentration of 2% of the total diet consumption, and animals were supplemented for 42 days. The total liver lipid content was determined, and the morphology of the organ was examined by optical microscopy. Peroxide and malondialdehyde indexes were determined in vitro in order to evaluate the oxidative stability of the supplements. Peroxide, malondialdehyde and 8-iso-PGF2α isoprostane and catalase were determined as biological lipid oxidation indicators. Results: Results indicated a low in vitro oxidation stability of commercial mixtures. Associations between conjugated linoleic acid consumption and malondialdehyde (r=-0.7914, p<0.0001), and catalase (r=-0.5991, p=0.008) were moderate, negative and significant, demonstrating that conjugated linoleic acid reduced in vivo lipid oxidation. Total hepatic lipid content did not increase (22.42%, (SD=1.40%), and the organ remained morphologically undamaged. Conclusion: However, even though this CLA supplementation protocol did reduce lipid oxidation, a tendency was observed to an increase of 8-iso-PGF2 alpha isoprostane and peroxides induced by conjugated linoleic acid. Further research may be needed to verify its antioxidant effect. © 2009 Revista de Nutrição.