Treatment with 100 µM linoleic acid resulted in 1303 regulated probes (2.78% of all probes). The scatterplots show log base 2 fluorescence intensity after a six-hour incubation period with 100 µM linoleic acid, 100 µM 13-HpODE or 100 µM hexanal in HGT-1 cells ( Figure 1). The impact of linoleic acid, 13-HpODE, and hexanal at the genomic level of HGT-1 cells was analyzed using a customized cDNA microarray. Moreover, it has been shown that the primary peroxidation product of linoleic acid, 13-hydroperoxy-9 Z,11 E-octadecadienoic acid (13-HpODE), is mainly decomposed in the stomach into secondary peroxidation products such as its corresponding alcohols, epoxyketones and aldehydes, which were demonstrated to be partially incorporated into the intestinal lumen and further absorbed by enterocytes. However, studies on the effects of structurally-characterized primary and secondary peroxidation products of linoleic acid are lacking. On the other hand, animal feeding studies have also shown that dietary oxidized fats lead to a decrease in triacylglycerols and cholesterol in liver and plasma, and to the regulation of genes involved in lipid metabolism. On the one hand, oxidized fats and oils have been hypothesized to be harmful to health and associated with, e.g., the development of atherosclerosis. In several animal feeding studies, highly oxidized fats with peroxide values >10 meq/kg oil have been administered. Other prominent sources of linoleic acid, and therefore prone to oxidation, are walnuts, pine nuts, and pecans. Linoleic acid can be found in vegetable oils commonly used for deep-frying, such as rice bran, safflower, sunflower, soybean, corn, and canola oil.
INJECTOR CRANKING PRIMER ENRICHMENT EVOM FREE
The free fatty acid, linoleic acid, is an essential unsaturated fatty acid and the predominant omega-6 polyunsaturated fatty acid in the Western diet. Under thermal treatment, free fatty acids undergo faster oxidation processes than under non-heated conditions. Here, primary and secondary lipid peroxidation products are formed through autoxidation or photo-oxidation reactions of unsaturated fatty acids, resulting in the generation of lipid hydroperoxides and further decomposition products, such as aldehydes, carboxylic acids, alcohols, or hydrocarbons. One of the major determinants of the quality of a frying oil are lipid peroxidation products. During the deep-frying process, the frying oils are severely heated, resulting in multiple chemical reactions of the oils’ constituents. Among them, the popularity of deep-fried products is based on convenience, their crispy texture, and pleasant mouth feel compared to non-fried foods. In industrialized countries, the habitual diet is characterized by a high intake in dietary fats, mainly originating in heat-treated foods.
An integrated genomic and metabolomic pathway analysis revealed an impact of the linoleic acid peroxidation products, 13-HpODE and hexanal, primarily on pathways related to amino acid biosynthesis ( p < 0.05), indicating that peroxidation of linoleic acid plays an important role in the regulation of intracellular amino acid biosynthesis. Exposure of HGT-1 cells to either 100 µM linoleic acid or 100 µM 13-HpODE resulted in the formation of approximately 1 µM of the corresponding hydroxy fatty acid, 13-HODE, in the basolateral compartment, whereas a mean concentration of 0.20 ± 0.13 µM hexanal was quantitated after an equivalent application of 100 µM hexanal. The genomic and metabolomic approach was preceded by an up-to-six-hour exposure study applying 100 µM of each test compound to the apical compartment in order to quantitate the compounds’ recovery at the basolateral side.
This study investigates the impact of linoleic acid, one of the most abundant polyunsaturated fatty acids in vegetable oils, and its primary and secondary peroxidation products, 13-HpODE and hexanal, on genomic and metabolomic pathways in human gastric cells (HGT-1) in culture. Dietary intake of oxidized vegetable oils has been associated with various biological effects, whereas knowledge about the effects of structurally-characterized lipid peroxidation products and their possible absorption into the body is scarce. During deep-frying processes, vegetable oils are subjected to high temperatures which result in the formation of lipid peroxidation products. The Western diet is characterized by a high consumption of heat-treated fats and oils.
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