Triacylglycerols (TAG) contain sites of unsaturation that are susceptible to oxidation when exposed to air, or when heated. These TAG form a variety of primary oxidation products that contain fatty acids with multiple functional groups, such as hydroperoxides, epoxides, ketones and alcohols. Fatty acid oxidation products have been shown to represent a significant atherosclerotic risk. Oxidation products have been shown to be incorporated into brush border cells, and then into low-density lipoprotein (LDL). New analytical methodologies that the P.I. is pioneering have allowed large, high molecular weight (MW) TAG oxidation products (TAGOX), made from the joining together of several oxidized TAG, to be directly identified for the first time. These large, oligomeric TAGOX deserve further study because they are routinely consumed as part of the typical American diet, yet they have never before been characterized. We propose to use liquid chromatography coupled with electrospray ionization-mass spectrometry (ESI-MS) for analysis of the large oxygen-containing oligomers produced by heated oils. We will characterize intact oligomers containing two (dimers), three (trimers) or four (tetramers) triacylglycerols covalently bonded together. These molecules contain oxygen functional groups that are reactive and could allow oxidized fatty acids to be incorporated into biological tissue, such as low-density lipoprotein (LDL). We will analyze oxidation products from triolein (the major component in olive and canola oils) heated for 0 hr., 1 hr., 3 hr., and 6 hr. to determine the onset and extent of degradation due to oxidation. We will examine heated oil samples treated with 0 ppm, 100 ppm, and 400 ppm alpha tocopherol (vitamin E) to demonstrate that oxidation can be significantly reduced by incorporation of antioxidants. This research will represent the first time that the specific molecular species of high molecular weight oxidation products have been directly identified. We propose to use LC/MS to study the products formed by model oils and also the products extracted from potato chips fried in the heated oils. The characterization of these high molecular weight oxidized oligomers will provide unprecedented insight into the mechanisms by which dietary oils are oxidized and made available for incorporation into biological tissue. ? ?
