Polyunsaturated chylomicrons

The major lipid-soluble antioxidant primarily associated with lipid membranes is a-tocopherol (vitamin E). Circulating a-tocopherol is carried by chylomicrons, LDL and HDL and also has extracellular antioxidant capacities. As a chain-breaking antioxidant, it short circuits the propagation phase of lipid peroxidation because the peroxyl radical will react with a-tocopherol more rapidly than a polyunsaturated ffitty acid (Burton and Traber, 1990). The resulting a-tocopheryl radical reacts with a second peroxyl radical to form an inactive, nonradical complex. In vitro, ascorbate regenerates the tocopheryl radical into its native non-radical form (Burton and Traber, 1990). 

Figure 5.22 Origins and metabolism of polyunsaturated fatty acids in the fetus. The numbers refer to the three alternatives outlined in the text. The sources of maternal plasma fatty acids could be dietary (as chylomicrons) or from the liver (as VLDL) or adipose tissue (as albumin-bound NEFA).

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