title: Analysis of the kinetics of lipid peroxidation in terms of characteristic time-points.
abstract: Measuring peroxidation of aggregated lipids in model systems (liposomes, micelles, emulsions or microemulsions) as well as in samples of biological origin ex vivo (isolated lipoproteins, blood sera or plasma) is widely used in medical and biological investigations, to evaluate the oxidative stress, antioxidants' efficiency and lipid oxidizability in different pathophysiological states. To avoid possible artifacts, such investigations must be based on the time course of peroxidation (i.e. on kinetic studies). To be able to compare complex kinetic profiles, it is important to characterize them in terms of mechanistically meaningful and experimentally unequivocal parameters. In this review, we characterize the typically observed continuous kinetic profiles in terms of a limited number of characteristic time-points (both commonly used and additional time-points and their combinations) that can be derived from experimental time-dependencies. The meaning of each of the experimentally observed characteristic parameters is presented in terms of rate constants and concentrations, derived on the basis of mechanistic considerations. Theoretical expressions for these characteristic parameters are based on a model that includes both the inhibited peroxidation and the uninhibited peroxidation occurring after consumption of the antioxidant(s). Comparison between theoretically predicted dependencies and experimental data support our treatment considered with special emphasis on transition metals-induced peroxidation of lipoproteins.
authors: Department of Physiology and Pharmacology, Tel Aviv University, Sackler Medical School, Ramat Aviv, Tel Aviv 69978, Israel. Electronic address: ilyap@post.tau.ac.il.
authors: Ilya
authors: I
authors: Pinchuk
authors: Department of Physiology and Pharmacology, Tel Aviv University, Sackler Medical School, Ramat Aviv, Tel Aviv 69978, Israel.
authors: Dov
authors: D
authors: Lichtenberg
mesh_terms: D006861:Hydrogen Peroxide / Q000737:chemistry; D015227:Lipid Peroxidation; D008055:Lipids / Q000737:chemistry*; D008670:Metals / Q000737:chemistry; D008962:Models, Theoretical; D013997:Time Factors
chemical_list: D008055:Lipids; D008670:Metals; D006861:Hydrogen Peroxide
keywords: 2,2′-azobis(2-amidinopropane) dihydrochloride, organic generator of free radicals; AAPH; AH; Cu(B); HP=LOOH; Hydroperoxides; L, LO, LO(2); LDL; LDL peroxidation kinetics; LH; Lag; Lipid oxidation; OD; OS; PUFA; R; R(i); TMI; antioxidant*; any free radical produced in the considered system (e.g. AAPH-derived or lipid hydroperoxide-derived radicals); copper ions bound to lipoprotein particles; initiation rate, rate of free radical production; k; lipid hydroperoxide*; lipid, mostly PUFA, (*index zero relates to zero time, i.e. to concentration prior to the beginning of peroxidation, see also footnote to Table 2); lipid-derived free radicals: alkyl, alkoxyl and alkylperoxyl radical, respectively; low density lipoprotein; optical density; oxidative stress; polyunsaturated fatty acid; rate constants (indices are explained in Section 4 and Table 3); reaction rates (indices are explained in Sections 3 and 4); transition metal ions; v