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Many analytical methods are used to measure the antioxidative activity of substances yet little is known about the comparability of the test results between laboratories. After an initial evaluation of a broad range of methods conducted by one laboratory, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, the trolox equivalent antioxidant capacity (TEAC) assay, the lipid assay (or 2,2'-azobis(2-aminepropane) (ABAP) assay) and the thiobarbituric acid (TBA) assay were selected to be evaluated in the interlaboratory study. The antioxidative potentials of trolox, tocopherol, lipochroman-6, ascorbic acid, 4-methyl-brenzcatechin, and/or 3,5-di-tert-butyl-4-hydroxytoluene (BHT) were assessed using each of the methods. These methods were then evaluated in respect of their reproducibility and classification properties. Based on the results of this study, the DPPH assay followed by the TEAC assay yielded the best results based on reproducibility and sensitivity both within one laboratory and between laboratories. The results of the interlaboratory study were then compared with the single center results obtained from the commercially available photochemolumiescence (PCL) kit. To assess the transferability of chemical data to biological systems, they were also compared with the single center results obtained using the cell-based Dichlorodihydrofluoresceine (DCFH) assay.

Oxidation is widely assumed to play a causal role in the pathogenesis of atherosclerosis. Oxidative modification of low density lipoprotein (LDL) can be followed by analyzing the lag phase of the conjugated diene formation at 234 nm in LDL exposed to Cu2+. This procedure is restricted to isolated LDL fractions. To make this assay applicable to different biological systems, the present paper introduces a method to determine the time course of lipid peroxidation by measuring the EPR signal intensity and thereby the concentration of the radicals formed. Stable radical spin adducts were generated using the spin trap PBN (N-tert.-butyl-alpha-phenylnitrone) and were detected by EPR spectroscopy. Comparing the specific formation of radicals and the generation of conjugated dienes as measured by UV absorbance revealed analogous lag, propagation and decomposition phases.

Numerous studies suggest that supplemental vitamin E prior to or during vast surgeries might diminish or even prevent ischemia/reperfusion-induced injuries. In the present placebo-controlled study male Sprague-Dawley rats were supplemented parenterally or orally with alpha-tocopherol for three consecutive days. The applied amount of alpha-tocopherol was 2.3 micromol per day for oral and 1.2 micromol per day for parenteral supplementation. The enrichment of vitamin E concentrations in plasma and tissue samples (aortic endothelium, liver, and lung) was determined by HPLC. The vitamin E level was elevated following intravenous supplementation in plasma (21.4 +/- 1.9 micromol/L vs. 10.2 +/- 1.7 micromol/L in parenteral control group), in aortic endothelium (1.1 +/- 0.2 pmol/mm2 vs. 0.5 +/- 0.1 pmol/mm2) and in liver and lung (41.3 +/- 7.5 pmol/mg vs. 22.9 +/- 6.5 pmol/mg and 75.6 +/- 13.6 pmol/mg vs. 51.7 +/- 5.9 pmol/mg, respectively). Oral supplementation for three days also led to an increased level in liver (38.2 +/- 7.7 pmol/mg vs. 22.9 +/- 6.6 pmol/mg in oral control group) and in lung (67.8 +/- 5.7 pmol/mg vs. 51.7 +/- 9.3 pmol/mg) but not in aortic endothelium or plasma (0.8 +/- 0.3 pmol/mm2 vs. 0.6 +/- 0.3 pmol/mm2 and 12.0 +/- 2.2 micromol/L vs. 10.7 +/- 2.6 micromol/L).

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