Lipid peroxidation: the role or Ca2+ and protection by calcinine

When calcinine (A-23187) (2 mu M), a known Ca2+ ionophore, is present, a significant protection is observed to a mitochondrial suspension undergoing lipid peroxidation by Fe2+-citrate complex. A-23187 can remove Ca2+, which seems to have an important role in the lipid peroxidation process, from its 'lesive sites' and consequently preventing the damage. This information has importance in terms of knowing the mechanisms and avoiding the damages of lipid peroxidation that occur in some pathological cases such as tumor promotion and hemochromatosis.

Ferrous-iron induces lipid peroxidation with little damage to energy transduction in mitochondria

Addition of ferrous sulfate, but not ferric chloride, in micromolar concentrations to rat liver mitochondria induced high rates of consumption of oxygen. The oxygen consumed was several times in excess of the reducing capacity of ferrous-iron (O: Fe ratios 5�8). This occurred in the absence of NADPH or any exogenous oxidizable substrate. The reaction terminated on oxidation of ferrous ions. Malondialdehyde (MDA), measured as thiobarbituric acid-reacting material, was produced indicating peroxidation of lipids. The ratio of O2: MDA was about 4: 1. Pretreatment of mitochondria with ferrous sulfate decreased the rate of oxidation (state 3) with glutamate (+malate) as the substrate by about 40% but caused little damage to energy tranduction process as represented by ratios of ADP: O and respiratory control, as well as calcium-stimulated oxygen uptake and energy-dependent uptake of [45Ca]-calcium. Addition of succinate or ubiquinone decreased ferrous iron-induced lipid peroxidation in intact mitochondria. In frozen-thawed mitochondria, addition of succinate enhanced lipid peroxidation whereas ubiquinone had little effect. These results suggest that ferrous-iron can cause peroxidation of mitochondrial lipids without affecting the energy transduction systems, and that succinate and ubiquinone can offer protection from damage due to such ferrous-iron released from the stores within the cells.

Selective inhibition of inducible nitric oxide synthase prevents lipid peroxidation in cartilage from patients with osteoarthritis.

INTRODUCTION: Emerging evidence indicates that nitric oxide (NO), which is increased in osteoarthritic (OA) cartilage, plays a role in 4-hydroxynonenal (HNE) generation through peroxynitrite formation. HNE is considered as the most reactive product of lipid peroxidation (LPO). We have previously reported that HNE levels in synovial fluids are more elevated in knees of OA patients compared to healthy individuals. We also demonstrated that HNE induces a panoply of inflammatory and catabolic mediators known for their implication in OA cartilage degradation. The aim of the present study was to investigate the ability of inducible NO synthase (iNOS) inhibitor, L-NIL (L-N6-(L-Iminoethyl)Lysine), to prevent HNE generation through NO inhibition in human OA chondrocytes. METHOD: Cells and cartilage explants were treated with or without either an NO generator (SIN or interleukin 1beta (IL-1β)) or HNE in absence or presence of L-NIL. Protein expression of both iNOS and free-radical-generating NOX subunit p47 (phox) were investigated by western blot. iNOS mRNA detection was measured by real-time RT-PCR. HNE production was analysed by ELISA, Western blot and immunohistochemistry. S-nitrosylated proteins were evaluated by Western Blot. Prostaglandin E2 (PGE2) and metalloproteinase 13 (MMP-13) levels as well as glutathione S-transferase (GST) activity were each assessed with commercial kits. NO release was determined using improved Griess method. Reactive oxygen species (ROS) generation was revealed using fluorescent microscopy with the use of commercial kits. RESULTS: L-NIL prevented IL-1β-induced NO release, iNOS expression at protein and mRNA levels, S-nitrosylated proteins and HNE in a dose dependent manner after 24h of incubation. Interestingly, we revealed that L-NIL abolished IL-1β-induced NOX component p47phox as well as ROS release. The HNE-induced PGE2 release and both cyclooxygenase-2 (COX-2) and MMP-13 expression were significantly reduced by L-NIL addition. Furthermore, L-NIL blocked the IL-1β induced inactivation of GST, an HNE-metabolizing enzyme. Also, L-NIL prevented HNE induced cell death at cytotoxic levels. CONCLUSION: Altogether, our findings support a beneficial effect of L-NIL in OA by preventing LPO process in NO-dependent and/or independent mechanisms.

Lipid peroxidation and generation of hydrogen peroxide in frozen-thawed ram semen cryopreserved in extenders with antioxidants

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Alterations in chlorophyll a fluorescence, pigment concentrations and lipid peroxidation to chilling temperature in coffee seedlings

Coffea arabica L. is considered to be sensitive to low temperatures throughout its life cycle. In some Brazilian regions, seedling production occurs under shade conditions and during the winter, with average temperatures of around 10 °C. The formation and functioning of the photosynthetic apparatus are strongly controlled by temperature. This study aimed to assess the changes that occurred in pigment contents, lipid peroxidation and variables of chlorophyll a fluorescence during the greening process of coffee seedlings submitted to chilling. Results indicate that saturation of the photosynthetic activity of coffee seedlings occurred before saturation of the accumulation of chloroplastid pigments. Pigment accumulation during the greening process is far beyond the metabolic needs for the maintenance of photosynthetic activity, more specifically of photosystem II. Coffee seedlings attained a quantum yield equivalent to that of the control with approximately half the chlorophyll a and b contents and around 40% of the carotenoid. Low temperature decreases the metabolism of seedlings, consequently reducing free radical production and lipid peroxidation. The chilling temperature (10 °C) used inhibited the accumulation of chloroplast pigments, in turn altering the capacity of the photosynthetic tissue of etiolated coffee seedlings to capture and transfer photon energy to the photosystem II reaction centre. These alterations were better demonstrated by O-J-I-P chlorophyll a fluorescence transients, rather than F v/F m and F v/F 0 ratios. © 2009 Elsevier B.V. All rights reserved.

Influence of beta(S) allele in the lipid peroxidation and antioxidant capacity parameters

Introduction: The oxidative process plays a fundamental role in the pathophysiology of sickle cell anemia (SCA), and population and environmental characteristics may influence redox balance. The aim of this study was to evaluate lipid peroxidation and antioxidant capacity in Brazilian Hb S carriers undergoing different therapies.MethodsBlood samples from 270 individuals were analyzed (Hb SS, n=68; Hb AS, n=53, and Hb AA, n=149). Hemoglobin genotypes were assessed through cytological, electrophoretic, chromatographic, and molecular methods. Plasma lipid peroxidation and antioxidant capacity were measured by spectrophotometric methods.ResultsPatients with SCA who used iron-chelating drugs combined with hydroxyurea, associated with regular transfusions, showed lower levels of TBARS (P <= 0.05), higher levels of TEAC (P <= 0.01), and lower TBARS/TEAC ratio (R=255.8). The redox profile of Hb AS subjects was not statistically different (P>0.05) from that of Hb AA subjects.ConclusionThe data suggest that oxidative stress is lower in the patients with SCA who received regular blood transfusions associated with the combined use of HU and iron chelators than the group received only HU. The redox system of the Hb AS carriers is compatible with the control group.

Occurrence of Lipid Peroxidation in Brain Microsomes in the Presence of NADH and Vanadate

Oxidation of NADH by rat brain microsomes was stimulated severalfold on addition of vanadate. During the reaction, vanadate was reduced, oxygen was consumed, and H2O2 was generated with a stoichiometry of 1:1 for NADH/O2, as in the case of other membranes. Extra oxygen was found to be consumed over that needed for H2O2 generation specifically when brain microsomes were used. This appears to be due to the peroxidation of lipids known to be accompanied by a large consumption of oxygen. Occurrence of lipid peroxidation in brain microsomes in the presence of NADH and vanadate has been demonstrated. This activity was obtained specifically with the polymeric form of vanadate and with NADH, and was inhibited by the divalent cations Cu2+, Mn2+, and Ca2+, by dihydroxy-phenolic compounds, and by hemin in a concentration-dependent fashion. In the presence of a small concentration of vanadate, addition of an increasing concentration of Fe2+ gave increasing lipid peroxidation. After undergoing lipid peroxidation in the presence of NADH and vanadate, the binding of quinuclidinyl benzylate, a muscarinic antagonist, to brain membranes was decreased.

Microsomal redox systems in brown adipose tissue: high lipid peroxidation, low cholesterol biosynthesis and no detectable cytochrome P-450

The presence of redox systems in microsomes of brown adipose tissue (BAT) in cold exposed rats was investigated and compared with liver. BAT microsomes showed high activity of lipid peroxidation measured both by the formation of malondialdehyde (MDA) and by oxygen uptake. NADH and NADPH dependent cytochrome c reductase activity were present in both BAT and liver microsomes. Aminopyrine demethylase and aniline hydroxylase activities, the characteristic detoxification enzymes in liver microsomes could not be detected in BAT microsomes. BAT minces showed very poor incorporation of [1-14C]acetate and [2-14C]-mevalonate in unsaponifiable lipid fraction compared to liver. Biosynthesis of cholesterol and ubiquinone, but not fatty acids, and the activity of 3-hydroxy-3-methyl glutaryl CoA reductase appear to be very low in BAT. Examination of difference spectra showed the presence of only cytochrome b 5 in BAT microsomes. In addition to the inability to detect the enzyme activities dependent on cytochrome P-450, a protein with the characteristic spectrum, molecular size in SDS-PAGE and interaction with antibodies in double diffusion test, also could not be detected in BAT microsomes. The high activity of lipid peroxidation in microsomes, being associated with large oxygen uptake and oxidation of NADPH, will also contribute to the energy dissipation as heat in BAT, considered important in thermogenesis.

Role of lipid peroxidation in impairment of mitochondrial function at complex I by methyl isocyanate treatment of rats in vivo

The subcutaneous administration of methyl isocyanate (MIC) in 1.0 LD50 dose in rats caused a significant effect on hepatic mitochondrial function only at complex I region of the respiratory chain. MIC administration at 1.0 LD50 dose also resulted in significant increases in malondialdehyde and ferrous ion concentration in liver mitochondria. It is suggested that the augmented lipid peroxidation in hepatic mitochondria, catalyzed by iron, possibly mobilized from intracellular stores leads to the inhibition of enzymes of mitochondrial respiration at complex I region, in vivo, in rats receiving a lethal dose of MIC subcutaneously.

Influence of cadmium on lipid peroxidation and antioxidant enzymes in isolated rat hepatocytes

Cadmium (Cd) influences lipid peroxidation (LPO) by enhancing peroxidation of membrane lipids and by disturbing the antioxidant system of cells. In isolated rat hepatocytes, LPO was observed in cells incubated with Cd (50-250 mu M) for various time periods up to 90 min. The antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT) were inhibited along with depletion of glutathione (GSH) in hepatocytes treated with Cd. The results show that Cd influences LPO in rat hepatocytes due to decrease in antioxidant status.