2-parinarolyllecithin and parinaric-acid

cis-Parinaric acid is increasingly being used in eukaryotic cells as a very sensitive marker for the initial stages of lipid peroxidation. Despite the increased application of this probe, no extensive validation, especially in cellular systems, has been performed. cis-Parinaric acid can either be inserted freely into biomembranes or incorporated (bio)synthetically into lipids (parinaroyl-lipid). Therefore, a direct comparison was made between the peroxidative behaviour of the two parinaroyl probes and the endogenous polyunsaturated fatty acids arachidonic and linoleic acid, in both an artificial lipidic system and in cultured neonatal rat heart cells. Three different radical generating systems were used, i.e., hydrogen peroxide, cumene hydroperoxide and the thermo-labile 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH). The data demonstrate that the peroxidation rate of cis-parinaric acid is higher than that of the parinaroyl, arachidonoyl and linoleoyl lipids. The latter three displayed comparable peroxidation rates, showing that the peroxidative decay of parinaroyl-lipid is a good marker for the degradation of endogenous polyunsaturated fatty acids. Experimental results using the freely inserted cis-parinaric acid could potentially lead to an overestimation of the inflicted damage and should be interpreted with care. In addition, a comparison was made with the measurement of conjugated dienes and malon dialdehyde as thiobarbituric acid reactive substances. The results demonstrate that measurement of conjugated dienes and malon dialdehyde only provide information on peroxidative processes in vitro, but are not suitable for in-depth studies in cultured cells. In contrast, the use of the parinaroyl probes is a suitable, straightforward, sensitive and reproducible method for detecting the initial stages of lipid peroxidation in living cells.

Topics: Animals; Cells, Cultured; Fatty Acids, Unsaturated; Fluorescent Dyes; Free Radicals; Kinetics; Lipid Peroxidation; Liposomes; Lysophosphatidylcholines; Models, Biological; Myocardium; Oxidants; Phospholipids; Rats; Reproducibility of Results; Spectrometry, Fluorescence

The decrease in fluorescence of conjugated polyenic acyl chains is used as a sensitive assay for lipid peroxidation. The fatty acid cis-trans-trans-cis-9,11,13, 15-octadecatetraenoic acid (cis-parinaric acid) is introduced into liposomal membranes as free fatty acid or, by using the PC specific transfer protein from bovine liver, as 1-palmitoyl-2-cis-parinaroyl-sn-glycero-3-phosphocholine. The peroxidation process as monitored by the decrease in fluorescence intensity is compared with other peroxidation assay systems. Applications of the new assay system are discussed.

Topics: Androgen-Binding Protein; Carrier Proteins; Copper; Fatty Acids, Unsaturated; Fluorescent Dyes; Hydrogen Peroxide; Lipid Peroxides; Liposomes; Lysophosphatidylcholines; Phosphatidylcholines; Phospholipid Transfer Proteins; Spectrometry, Fluorescence