Oxidized Cyclic Fatty Acid Monomers From Polyunsaturated Oils: Formation, Structures and Potential Biological Activities

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Cyclic fatty acid monomers (CFAM) are part of the human diet. They are formed at low levels in edible oils during thermal processing operations such as frying, and refining. Despite documented negative biological acvitivies and their presence in processed foods, CFAMs remain underinvestigated and it is imperative to address this situation. The long term goals of the research program are 1) to gain a good understanding of reaction mechanisms involved in the transformation of lipid molecules at frying temperatures and develop methods for their control; 2) to assess their potential bioactivities; and 3) to explore their value-addition in different applications. Moving towards our long term goals, we have, in the past 5 years, studied the formation kinetics of CFAMs; synthesized a labeled (2H) CFAM, and demonstrated that the most abundant CFAMs in foods cause an accumulation of triglycerides in the liver (fatty liver), alter the activities of liver enzymes, and, most importantly, are much more potent proatherogenic agents than industrial trans fats which have been banned in Canada! We also conducted two preliminary studies: 1) since low levels of CFAM disrupt the liver enzyme metabolism, we hypothesized that heated PUFA oils containing CFAM may affect enzymatic activities of microbes and have antimicrobial effects: we observed a growth inhibition on four bacteria; 2) we hypothesized that polyunsaturated CFAM can oxidize readily into CFAM-Ox: we found that isomers of CFAMs oxidize faster than linoleic acid, supporting that levels of CFAM in oils are underestimated as they exclude CFAM-Ox. These results from our work constitute a very significant progress towards our long term goal and have now paved the way to undertake studies on the production, characterization and biological activities of CFAM-Ox. We hypothesize that this potent unknown new class of products, the CFAM-Ox, whose structures may be similar to those of essential signal molecules prostanoids, phytoprostans and phytofurans, could, at trace levels, interfere with critical reactions and signal transduction in biological systems. The specific objectives for the next 5 years are: 1) To conclude our studies on the mechanisms by which CFAMs are formed at frying temperatures; 2) To determine the level of the putative CFAM-Ox in heated/frying oils and carry out their chemical characterization; and 3) To initiate the evaluation of bioactivities of CFAM-Ox such as their antimicrobial potential. Knowledge gained from this research will lead to a better understanding of the chemical mechanisms and the kinetics involved in the formation of CFAM and CFAM-Ox during the frying of foods; to the development of strategies to control or retard those degradative reactions; and to the evaluation of their potential biological activities. This program will contribute to the training for 4-5 graduate students, in Chemistry of Fats and Oils and Lipidomics, an area of strategic importance to Canada.