Antioxidant and pro-oxidant effects of red wine and its fractions on Cu(II) induced LDL oxidation evaluated by absorbance and chemiluminescence measurements

Abstract

Cu(II) mediated low density lipoprotein (LDL) oxidation has been followed by the changes in absorbance at 234 nm and the emitted low level chemiluminescence (CL). The similarity of the time profiles allows us to conclude that the emitted CL is due to the decomposition of a transient product, most likely a hydroperoxide. Red wine, as well as its fractions, afford a noticeable protection when added prior to the start of the LDL oxidation process. On the other hand, when they are added after the onset of the autocatalytic oxidation phase, red wine and its fractions behave as pro-oxidants. This is particularly evidenced by a strong burst of CL (enhancement of the light by a factor approximately 20). This burst is reduced by metal chelators (EDTA and DFO) and can be associated to a sequence of reactions such as XOH + Cu(II) --> X* + H(+) + Cu(I), Cu(I) + LOOH --> chemiluminescence where XOH is a phenolic compound and LOOH is a peroxide-like compound produced in the LDL oxidation.

Interaction and reactivity of urocanic acid towards peroxyl radicals

“…LDL isolation was performed as previously described. 15 Oxidative degradation of urocanic acid Different concentrations of trans-urocanic acid were incubated at 37°C in the presence of 10 mM AAPH (10 mM phosphate buffer, pH 7.0) under aerobic conditions. In some experiments, mixtures of trans-and cis-isomers were exposed to the peroxyl radicals generated by AAPH.…”

“…For this reason, the extent of LDL oxidation induced by Cu(II) addition was followed by the emitted chemiluminescence. 15 The chemiluminescence was measured in polyethylene vials containing LDL (11.3 µg/ml) and copper sulphate (5 µM) with different concentrations of urocanic acid (0.5-2 mM) in PBS buffer (pH 7.4) at room temperature (23°C). Experiments were also carried out employing 10 mM AAPH (PBS buffer, pH 7.4 at 23°C) as a promoter of LDL oxidation.…”

A Comparative Study of Analytical Methods for Determination of Polyphenols in Wine by HPLC/UV-Vis, Spectrophotometry and Chemiluminometry

“…Chemiluminescence, the emission of light as a consequence of relaxation of kind, which it is evoked between chemical reactions, has become very useful technique for studying oxidation of organic materials (Costin et al, 2003;Garcia-Campana  Baeyens, 2001;Hötzer et al, 2005;Kočar et al, 2008;Kuse et al, 2008). ABEL ® (analysis by emitted light) antioxidant test kit, which contains photo protein Pholasin ® , was used.…”

Antioxidant effect of 5-amino salicylic acid on copper-mediated LDL oxidation

“…Prior to oxidation, EDTA in the LDL solution was removed with two passages through an Econo-Pac 10G desalting column (Bio-Rad, Richmond, CA) hydrated and eluted with phosphate buffered saline (PBS). Protein concentrations in LDL preparations were determined by a modification of the Lowry method using bovine serum albumin as a reference standard (Hotzer et al, 2005). After elimination of EDTA, LDL samples were kept at 4 ºC and used less than five days after purification.…”