A curvilinear approach to the kinetic analysis of linoleate peroxidation in aqueous liposomes by 2,2'azobis(2-amidoinopropane) dihydrochloride

Lipid peroxidation is a common feature of many chemical and biological processes, and is governed by a complex kinetic scheme. A fundamental stage in kinetic investigations of lipid peroxidation is the accurate determination of the rate of peroxidation, which in many instances is heavily reliant on the method of finite differences. Such numerical approximations of the first derivative are commonly employed in commercially available software, despite suffering from considerable inaccuracy due to rounding and truncation errors. As a simple solution to this, we applied three empirical sigmoid functions (viz. the Prout-Tompkins, Richards & Gompertz functions) to data obtained from the AAPH-mediated peroxidation of aqueous linoleate liposomes in the presence of increasing concentrations of Trolox, evaluating the curve fitting parameters using the widely available Microsoft Excel Solver add-in. We have demonstrated that the five-parameter Richards' function provides an excellent model for this peroxidation, and when applied to the determination of fundamental rate constants, produces results in keeping with those available in the literature. Overall, we present a series of equations, derived from the Richards' function, which enables direct evaluation of the kinetic measures of peroxidation. This procedure has applicability not only to investigations of lipid peroxidation, but to any system exhibiting sigmoid kinetics.

Low-energy cranberry juice decreases lipid oxidation and increases plasma antioxidant capacity in women with metabolic syndrome

Cranberries, high in polyphenols, have been associated with several cardiovascular health benefits, although limited clinical trials have been reported to validate these findings. We tested the hypothesis that commercially available low-energy cranberry juice (Ocean Spray Cranberries, Inc, Lakeville-Middleboro, Mass) will decrease surrogate risk factors of cardiovascular disease, such as lipid oxidation, inflammation, and dyslipidemia, in subjects with metabolic syndrome. In a randomized, double-blind, placebo-controlled trial, participants identified with metabolic syndrome (n = 15-16/group) were assigned to 1 of 2 groups: cranberry juice (480 mL/day) or placebo (480 mL/day) for 8 weeks. Anthropometrics, blood pressure measurements, dietary analyses, and fasting blood draws were conducted at screen and 8 weeks of the study. Cranberry juice significantly increased plasma antioxidant capacity (1.5 ± 0.6 to 2.2 ± 0.4 µmol/L [means ± SD], P <.05) and decreased oxidized low-density lipoprotein and malondialdehyde (120.4 ± 31.0 to 80.4 ± 34.6 U/L and 3.4 ± 1.1 to 1.7 ± 0.7 µmol/L, respectively [means ± SD], P <.05) at 8 weeks vs placebo. However, cranberry juice consumption caused no significant improvements in blood pressure, glucose and lipid profiles, C-reactive protein, and interleukin-6. No changes in these parameters were noted in the placebo group. In conclusion, low-energy cranberry juice (2 cups/day) significantly reduces lipid oxidation and increases plasma antioxidant capacity in women with metabolic syndrome.

The influence of organophosphorus pesticide-methylparathion on protein, lipid metabolism and detoxifying enzymes in rohu (Labeo rohita)

Methylparathion (MP) is an organophosphorus insecticide used world wide in agriculture due to its high activity against a broad spectrum of insect pests. The aim of the study is to understand the effect of methylparathion on the lipid peroxidation, detoxifying and antioxidant enzymes namely catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione Stransferase (GST), total reduced glutathione (GSH), lipid peroxidation (LPO), acetylcholinesterase (AChE) and disease diagnostic marker enzymes in liver, sarcoplasmic (SP) and myofirbirllar (MF) proteins in muscles, lipids and histopathlogical changes in various organs of Labeo rohita of size 75 i 6g at lethal and sublethal level of exposure. The probit analysis showed that the lethal concentration (LC 50%) for 24, 48, 72 and 96h were 15.5mg/L, 12.3mg/L, 11.4mg/L and 10.2mg/L respectively which is much higher compared to the LC50 for juvenile fish. The LPO level and GST activity increased five folds and two folds respectively on exposure to methylparathion at 10.2 mg/L and the level of the enzymes increased, on sub lethal exposure beyond 0.25mg/L. AChE activity was inhibited by 74% at a concentration of 1.8mg/L and 90% at 5.4mg/L. The disease diagnostic marker enzymes AST, ALT, ALP and LDH increased by about 2, 3 ,3 and 2 folds respectively at pesticide concentration of 10.2mg/L when compared to control. On sub lethal exposure, however the enzymes did not show any significant changes up to 0.5mg/L. At a concentration of 10.2 mg/L, there was a three fold increase in myofibrillar proteins while the increase in sarcoplasmic protein was above 1.5 fold. On sub lethal exposure, significant alteration was noticed up to 30 days up to 1mg/L of methylparathion concentration. Further exposure up to 45 days increased sarcoplasmic proteins (upto 0.5mg/L). ln the case of myofibrillar proteins, noticeable changes were observed at 1mg/L concentration right from 15th day. The cholesterol content in brain tissues increased by about 27% at methylparathion concentration of 5.4 mglL. However at 0.25mg/L sub lethal concentration, no significant alteration was observed in enzyme activity, muscle proteins, lipids and histopathology of the tissues. The results suggest that methylparathion has the potential to induce oxidative stress in fish, and that liver, muscle and brains are more sensitive organs of Labeo rohita, with poor antioxidant potentials at higher concentrations of the pesticide. The various parameters studied in this investigation can also be used as biomarkers of methylparathion exposure.

Effects of lipid emulsions on lipid body formation and eicosanoid production by human peripheral blood mononuclear and polymorphonuclear cells

Background & aims: This study investigated the influence of four commercial lipid emulsions, Ivelip, ClinOleic, Omegaven and SMOFlipid (R), on lipid body formation, fatty acid composition and eicosanoid production by cultured human peripheral blood polymorphonuclear cells (PMN) and mononuclear cells (PBMC). Methods: PMN and PBMC were exposed to emulsions at concentrations ranging from 0.01 to 0.04%. Lipid body formation was assessed by microscopy, fatty acid composition by gas chromatography and eicosanoids by ELISA. Results: Stimulation of inflammatory cells and exposure to lipid emulsions promoted the formation of lipid bodies, but there did not appear to be differential effects of the emulsions tested. In contrast, there were differential effects of lipid emulsions on eicosanoid formation, particularly with regards to LTB4 production by PMN. Omegaven dramatically increased production of eicosanoids compared with the other emulsions in a dose-dependent manner. This effect was associated with a significantly higher level of lipid peroxides in the supernatants of cells exposed to Omegaven. Conclusions: Stimulation of inflammatory cells and exposure to lipid emulsions promotes lipid body formation and eicosanoid production, although the differential effects of different emulsions appear to be largely due to lipid peroxidation of unsaturated fatty acids in some emulsions in this in vitro system. (C) 2009 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Lipid hydroperoxide-induced and hemoglobin-enhanced oxidative damage to colon cancer cells

Epidemiological studies have indicated that Western diets are related to an increase in a series of malignancies. Among the compounds that are credited for this toxic effect are heme and lipid peroxides. We evaluated the effects of hemoglobin (Hb) and linoleic acid hydroperoxides (LAOOH) on a series of toxicological endpoints, such as cytotoxicity, redox status, lipid peroxidation, and DNA damage. We demonstrated that the preincubation of SW480 cells with Hb and its subsequent exposure to LAOOH (Hb + LAOOH) led to an increase in cell death, DCFH oxidation, malonaldehyde formation, and DNA fragmentation and that these effects were related to the peroxide group and the heme present in Hb. Furthermore, Hb and LAOOH alone exerted a toxic effect on the endpoints assayed only at concentrations higher than 100 mu M. We were also able to show that SW480 cells presented a higher level of the modified DNA bases 8-oxo-7,8-dihydro-2`-deoxyguanosine and 1,N(2)-etheno-2`-deoxyguanosine compared to the control. Furthermore, incubations with Hb led to an increase in intracellular iron levels, and this high level of iron correlated with DNA oxidation, as measured as EndoIII- and Fpg-sensitive sites. Thus, Hb from either red meat or bowel bleeding could act as an enhancer of fatty acid hydroperoxide genotoxicity, which contributes to the accumulation of DNA lesions in colon cancer cells. (C) 2011 Elsevier Inc. All rights reserved.

Fowl play and the price of petrel: long-living Procellariiformes have peroxidation-resistant membrane composition compared with short-living Galliformes

The membrane pacemaker hypothesis predicts that long-living species will have more peroxidation-resistant membrane lipids than shorter living species. We tested this hypothesis by comparing the fatty acid composition of heart phospholipids from long-living Procellariiformes (petrels and albatrosses) to those of shorter living Galliformes (fowl). The seabirds were obtained from by-catch of commercial fishing operations and the fowl values from published data. The 3.8-fold greater predicted longevity of the seabirds was associated with elevated content of peroxidation-resistant monounsaturates and reduced content of peroxidation-prone polyunsaturates and, consequently, a significantly reduced peroxidation index in heart membrane lipids, compared with fowl. Peroxidation-resistant membrane composition may be an important physiological trait for longevous species.

Synchrotron-FTIR microspectroscopy enables the distinction of lipid accumulation in thraustochytrid strains through analysis of individual live cells

The superior characteristics of high photon flux and diffraction-limited spatial resolution achieved by synchrotron-FTIR microspectroscopy allowed molecular characterization of individual live thraustochytrids. Principal component analysis revealed distinct separation of the single live cell spectra into their corresponding strains, comprised of new Australasian thraustochytrids (AMCQS5-5 and S7) and standard cultures (AH-2 and S31). Unsupervised hierarchical cluster analysis (UHCA) indicated close similarities between S7 and AH-7 strains, with AMCQS5-5 being distinctly different. UHCA correlation conformed well to the fatty acid profiles, indicating the type of fatty acids as a critical factor in chemotaxonomic discrimination of these thraustochytrids and also revealing the distinctively high polyunsaturated fatty acid content as key identity of AMCQS5-5. Partial least squares discriminant analysis using cross-validation approach between two replicate datasets was demonstrated to be a powerful classification method leading to models of high robustness and 100% predictive accuracy for strain identification. The results emphasized the exceptional S-FTIR capability to perform real-time in vivo measurement of single live cells directly within their original medium, providing unique information on cell variability among the population of each isolate and evidence of spontaneous lipid peroxidation that could lead to deeper understanding of lipid production and oxidation in thraustochytrids for single-cell oil development.

Oxidative stress status and lipid profiles of diabetic pregnant rats exposed to cigarette smoke

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

Neonatally-induced diabetes: lipid profile outcomes and oxidative stress status in adult rats

INTRODUÇÃO: Modelos experimentais são desenvolvidos com propósito de ampliar o entendimento dos mecanismos fisiopatológicos envolvidos no diabete. Os achados experimentais levam ao desenvolvimento de tratamentos alternativos para a manutenção das condições metabólicas normais. Existem vários estudos sobre o diabete induzido por streptozotocin mimetizando o quadro clínico do DM2. No entanto, a interação entre os níveis de glicose, perfil lipídico e estresse oxidativo nestes animais são escassos. Portanto, o objetivo do trabalho foi avaliar estes parâmetros em ratas Wistar adultas com diabete induzido com streptozotocin no período neonatal. MÉTODOS: Fêmeas recém-nascidas receberam streptozotocin (70mg/Kg, ip) no 5º dia de vida (n5-STZ). A glicemia foi medida no terceiro e quarto meses de vida dos animais. No final do quarto mês de vida, amostras de sangue foram coletadas e processadas para a dosagem de lipídios e marcadores de estresse oxidativo. RESULTADOS: A glicemia das ratas do grupo n5-STZ foi significativamente maior comparada às ratas do grupo controle (p<0,05). Não houve alteração nos níveis de colesterol total e triglicérides, peroxidação lipídica (TBARS), atividade da SOD e determinação da GSH-t (p>0,05) nas ratas n5-STZ em relação às ratas do grupo controle. No entanto, houve diminuição significativa no HDL-colesterol (p<0,05). CONCLUSÃO: Este modelo de indução de diabete em ratas causou hiperglicemia (120-360mg/dL), caracterizando o diabete moderado. Essa glicemia levou a alterações no HDL-colesterol, a qual não foi suficiente para prejudicar a atividade das enzimas antioxidantes ou marcadores da peroxidação lipídica na vida adulta. Além disso, esta investigação experimental contribuiu para entender os diferentes resultados encontrados em outros modelos deindução do diabete moderado em animais de laboratório, como também para a melhor compreensão dos mecanismos fisiopatológicos do diabete moderado ou da hiperglicemia em humanos.

Changes in lipid composition in hippocampus early and late after status epilepticus induced by kainic acid in wistar rats

Oxidative damage to biological membranes has been reported as a cause of alterations in many different diseases. We had previously reported lipid peroxidation in the kainic acid model of temporal epilepsy. In this study we evaluated earlier and later modifications in the lipid composition after status epileticus induced by kainic acid. Lipid composition was determined by thin-layer chromatography, in the cortex and hippocampus 12-14 h, 7-8, 75-80, or 140-150 days after the end of status epileticus. In the hippocampus there was a significant change in the lipid protein ratio after status epileticus and this was accompanied by an alteration in lipid composition in all tested times. These results suggested that lipid peroxidation induced by kainic acid could be accompanied by chronic changes in the lipid composition that could be related to the development of seizures.

Phospholipid oxidation generates potent anti-inflammatory lipid mediators that mimic structurally related pro-resolving eicosanoids by activating Nrf2.

Exposure of biological membranes to reactive oxygen species creates a complex mixture of distinct oxidized phospholipid (OxPL) species, which contribute to the development of chronic inflammatory diseases and metabolic disorders. While the ability of OxPL to modulate biological processes is increasingly recognized, the nature of the biologically active OxPL species and the molecular mechanisms underlying their signaling remain largely unknown. We have employed a combination of mass spectrometry, synthetic chemistry, and immunobiology approaches to characterize the OxPL generated from the abundant phospholipid 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (PAPC) and investigated their bioactivities and signaling pathways in vitro and in vivo. Our study defines epoxycyclopentenones as potent anti-inflammatory lipid mediators that mimic the signaling of endogenous, pro-resolving prostanoids by activating the transcription factor nuclear factor E2-related factor 2 (Nrf2). Using a library of OxPL variants, we identified a synthetic OxPL derivative, which alleviated endotoxin-induced lung injury and inhibited development of pro-inflammatory T helper (Th) 1 cells. These findings provide a molecular basis for the negative regulation of inflammation by lipid peroxidation products and propose a novel class of highly bioactive compounds for the treatment of inflammatory diseases.

Identification of a Saccharomyces cerevisiae Gene that Is Required for G1 Arrest in Response to the Lipid Oxidation Product Linoleic Acid Hydroperoxide*

Reactive oxygen species cause damage to all of the major cellular constituents, including peroxidation of lipids. Previous studies have revealed that oxidative stress, including exposure to oxidation products, affects the progression of cells through the cell division cycle. This study examined the effect of linoleic acid hydroperoxide, a lipid peroxidation product, on the yeast cell cycle. Treatment with this peroxide led to accumulation of unbudded cells in asynchronous populations, together with a budding and replication delay in synchronous ones. This observed modulation of G1 progression could be distinguished from the lethal effects of the treatment and may have been due to a checkpoint mechanism, analogous to that known to be involved in effecting cell cycle arrest in response to DNA damage. By examining several mutants sensitive to linoleic acid hydroperoxide, the YNL099c open reading frame was found to be required for the arrest. This gene (designated OCA1) encodes a putative protein tyrosine phosphatase of previously unknown function. Cells lacking OCA1 did not accumulate in G1 on treatment with linoleic acid hydroperoxide, nor did they show a budding, replication, or Start delay in synchronous cultures. Although not essential for adaptation or immediate cellular survival, OCA1 was required for growth in the presence of linoleic acid hydroperoxide, thus indicating that it may function in linking growth, stress responses, and the cell cycle. Identification of OCA1 establishes cell cycle arrest as an actively regulated response to oxidative stress and will enable further elucidation of oxidative stress-responsive signaling pathways in yeast.

Advanced glycation endproducts in horses with insulin-induced laminitis

Advanced glycation endproducts (AGEs) have been implicated in the pathogenesis of cancer, inflammatory conditions and diabetic complications. An interaction of AGEs with their receptor (RAGE) results in increased release of pro-inflammatory cytokines and reactive oxygen species (ROS), causing damage to susceptible tissues. Laminitis, a debilitating foot condition of horses, occurs in association with endocrine dysfunction and the potential involvement of AGE and RAGE in the pathogenesis of the disease has not been previously investigated. Glucose transport in lamellar tissue is thought to be largely insulin-independent (GLUT-1), which may make the lamellae susceptible to protein glycosylation and oxidative stress during periods of increased glucose metabolism. Archived lamellar tissue from horses with insulin-induced laminitis (n=4), normal control horses (n=4) and horses in the developmental stages (6 h, 12 h and 24 h) of the disease (n=12) was assessed for AGE accumulation and the presence of oxidative protein damage and cellular lipid peroxidation. The equine-specific RAGE gene was identified in lamellar tissue, sequenced and is now available on GenBank. Lamellar glucose transporter (GLUT-1 and GLUT-4) gene expression was assessed quantitatively with qRT-PCR in laminitic and control horses and horses in the mid-developmental time-point (24 h) of the disease. Significant AGE accumulation had occurred by the onset of insulin-induced laminitis (48 h) but not at earlier time-points, or in control horses. Evidence of oxidative stress was not found in any group. The equine-specific RAGE gene was not expressed differently in treated and control animals, nor was the insulin-dependent glucose transporter GLUT-4. However, the glucose transporter GLUT-1 was increased in lamellar tissue in the developmental stages of insulin-induced laminitis compared to control horses and the insulin-independent nature of the lamellae may facilitate AGE formation. However, due to the lack of AGE accumulation during disease development and a failure to detect an increase in ROS or upregulation of RAGE, it appears unlikely that oxidative stress and protein glycosylation play a central role in the pathogenesis of acute, insulin-induced laminitis.

S-allylmercaptocysteine reduces carbon tetrachloride-induced hepatic oxidative stress and necroinflammation via nuclear factor kappa B-dependent pathways in mice.

Purpose To study the protective effects and underlying molecular mechanisms of SAMC on carbon tetrachloride (CCl4)-induced acute hepatotoxicity in the mouse model. Methods Mice were intraperitoneally injected with CCl4 (50 μl/kg; single dose) to induce acute hepatotoxicity with or without a 2-h pre-treatment of SAMC intraperitoneal injection (200 mg/kg; single dose). After 8 h, the blood serum and liver samples of mice were collected and subjected to measurements of histological and molecular parameters of hepatotoxicity. Results SAMC reduced CCl4-triggered cellular necrosis and inflammation in the liver under histological analysis. Since co-treatment of SAMC and CCl4 enhanced the expressions of antioxidant enzymes, reduced the nitric oxide (NO)-dependent oxidative stress, and inhibited lipid peroxidation induced by CCl4. SAMC played an essential antioxidative role during CCl4-induced hepatotoxicity. Administration of SAMC also ameliorated hepatic inflammation induced by CCl4 via inhibiting the activity of NF-κB subunits p50 and p65, thus reducing the expressions of pro-inflammatory cytokines, mediators, and chemokines, as well as promoting pro-regenerative factors at both transcriptional and translational levels. Conclusions Our results indicate that SAMC mitigates cellular damage, oxidative stress, and inflammation in CCl4-induced acute hepatotoxicity mouse model through regulation of NF-κB. Garlic or garlic derivatives may therefore be a potential food supplement in the prevention of liver damage.