Chemiluminescence detection of 8a‐hydroperoxy‐tocopherone in photooxidized α‐tocopherol

Abstract

Photosensitized oxidation products of alpha-tocopherol were analyzed by reversed phase high-performance liquid chromatography (CL-HPLC) in combination with chemiluminescence detection, to measure hydroperoxide derivatives. An intense peak was observed on the chemiluminescence chromatogram, corresponding to 8a-hydroperoxy-alpha-tocopherone (alpha-tocopherol hydroperoxide), the identity of which was confirmed by 1H nuclear magnetic resonance and mass spectrometry. Observed peak intensities correlated with the peroxide value of oxidized alpha-tocopherol. As little as 50 pmol of 8a-hydroperoxy-alpha-tocopherone was detectable. The CL-HPLC method, which is specific for the detection of hydroperoxides, should prove useful in studies on tocopherol oxidation in foods and biological systems.

Analysis of the addition products of α‐tocopherol with phosphatidylcholine‐peroxyl radicals by high‐performance liquid chromatography with chemiluminescent detection

“…A mixture of CLA, Fe(III)AA, and trifluoroacetic acid in methanol as the postcolumn reagent was most suitable for this assay. Luminol has already been used in chemiluminescence-based HPLC assay for 8a-hydroperoxy-α-tocopherone under alkaline conditions (26). However, chemiluminescence was not observed when luminol was used instead for the assay of TOO-PC under acidic and alkaline conditions (data not shown).…”

“…CLA has been reported to be an effective amplifier of the chemiluminescence produced by iron-induced decomposition of lipid hydroperoxides (28). Thus, the produced free radicals (PC-OO • and PC-O • ) can react with CLA, and the resulting oxidized CLA in the excited state (CLA * ox ) emits chemiluminescence at 380 nm to return to its ground state (CLA ox ) (26,27).…”

Effects of Temperature and UV Light on Degradation of α‐Tocopherol in Free and Dissolved Form

“…In addition to extended exposure to certain temperatures, several other factors such as oxygen, alkali, light, minerals, and hydroperoxides degrade a-tocopherol [13]. The photooxidation of a-tocopherol has been studied by different groups [14][15][16][17][18][19]. Pirisi et al [14] showed that a solution of olive oil in hexane irradiated with artificial light (k = 290 nm), or sunlight degraded at a rate constant (k) of 1.86 9 10 -4 s -1 and 1.03 9 10 -4 s -1 , respectively with a halftime t 1/2 values of 112 and 62 min, respectively.…”

Ozonation of cholesterol in the presence of ethanol: Identification of a cytotoxic ethoxyhydroperoxide molecule

“…As shown in Figures 1 and 3, we succeeded in detecting 7α-ethoxy-5-OOH by using the HPLC-CL-MS system. This analytical system can easily identify the cholesterol ozonides bearing a hydroperoxide moiety, because detection by CL is highly specific for the hydroperoxide group (15)(16)(17)(19)(20)(21)(22)(23). Next, the cytotoxic effect of 7α-ethoxy-5-OOH on human lung adenocarcinoma A549 cells was investigated because the biological role of the cholesterol ozonation products has never been evaluated.…”