The effect of fat compositions with the varying ratio of polyunsaturated fatty acids (PUFAs) of families ω-3 and ω-6 on oxidation process intensity in microsomal fraction of rat liver has been investigated. The aim of the study was to investigate the level of markers of oxidative modification of lipids and proteins in microsomal fraction of rat liver. Fat components in the experiment diets were presented by sunflower oil, soybean oil and fish oil. Rats were fed using one of the fillowing 5 diets for the period of 4 weeks: 1) AIN-93 diet with 7% sunflower oil and fish oil, with the inclusion of linoleic acid, eicosapentaenoic acid and docosahexaenoic acid in the ratio of ω-6:ω-3 – 7:1 (control diet); 2) AIN-93 diet with 7% soybean oil, with the inclusion of linoleic acid and α-linolenic acid in the ratio of 7:1; 3) the diet containing only ω-6 PUFAs; 4) the diet containing only ω-3 PUFAs; 5) the diet without PUFAs. The fatty acid compositions of the diets were analysed by gas chromatography. We measured the primary and secondary lipoperoxidation products, proteins carbonyl derivatives and SH-groups of proteins. It was shown that inclusion of linoleic acid and α-linolenic acid in the ratio of 7:1 or ω-6 PUFAs into the animal diet increased lipid peroxidation in microsomal fraction of the rat liver as compared with the control group. Only ω-6 PUFAs increased the oxidative modification of proteins in microsomal fraction of the rat liver as compared with the control rat group. High dose of ω-3 PUFAs – eicosapentaenoic acid and docosahexaenoic acid had no influence on free radical oxidation of lipids and proteins. Using the diet without PUFAs increased oxidation process intensity in microsomal fraction of rat liver. According to our study, ω-6 PUFAs increased the oxidative modification of lipids and proteins in microsomal fraction of the rat liver. ω-3 PUFAs, in particular, eicosapentaenoic acid and docosahexaenoic acid, increased lipid and protein resistance to oxidative modification in microsomal fraction of the rat liver.
Retroconversion is a minor contributor to increases in eicosapentaenoic acid following docosahexaenoic acid feeding as determined by compound specific isotope analysis in rat liver
