Thickness determination of hydroperoxidized lipid bilayers from medium-resolution cryo-TEM images.

As the primary products of lipid oxidation, lipid hydroperoxides constitute an important class of lipids generated by aerobic metabolism. However, despite several years of effort, the structure of the hydroperoxidized bilayer has not yet been observed under electron microscopy. Here we use a 200 kV Cryo-TEM to image small unilamellar vesicles (SUVs) made (i) of pure POPC or SOPC, (ii) of their pure hydroperoxidized form, and (iii) of their equimolar mixtures. We show that the challenges posed by the determination of the thickness of the hydroperoxidized bilayers under these observation conditions can be addressed by an image analysis method that we developed and describe here.

Acarbose Mitigates Age-Dependent Alterations in Erythrocyte Membrane Transporters During Aging in Rats.

Acarbose (ACA), a well-studied and effective inhibitor of α-amylase and α-glucosidase, is a postprandial-acting antidiabetic medicine. The membrane of the erythrocyte is an excellent tool for analyzing different physiological and biochemical activities since it experiences a range of metabolic alterations throughout aging. It is uncertain if ACA modulates erythrocyte membrane activities in an age-dependent manner. As a result, the current study was conducted to explore the influence of ACA on age-dependent deteriorated functions of transporters/exchangers, disrupted levels of various biomarkers such as lipid hydroperoxides (LHs), protein carbonyl (PCO), sialic acid (SA), total thiol (-SH), and erythrocyte membrane osmotic fragility. In addition to a concurrent increase in Na+/H+ exchanger activity and concentration of LH, PCO, and osmotic fragility, we also detected a considerable decrease in membrane-linked activities of Ca2+-ATPase (PMCA) and Na+/K+-ATPase (NKA), as well as concentrations of SA and -SH in old-aged rats. The aging-induced impairment of the activities of membrane-bound ATPases and the changed levels of redox biomarkers were shown to be effectively restored by ACA treatment.

Oil bodies extracted from high-oil soybeans (Glycine max) exhibited higher oxidative and physical stability than oil bodies from high-protein soybeans.

Reports concerning the characteristics of soybean oil bodies (SOBs) isolated from high protein genotypes and high oil genotypes of soybeans available in the literature are insufficient and limiting. In this study, fatty acid compositions, total phenol and tocopherol contents, antioxidant capacity, and physicochemical stability of SOB emulsions recovered from three high-protein and three high-oil genotype soybeans were comparatively investigated. Principal component analysis showed that all six SOB samples could be easily discriminated based on the cultivar characteristics. Overall, the SOBs derived from the high-protein soybeans exhibited higher polyunsaturated fatty acid (PUFA) contents, while the SOBs derived from the high-oil soybeans had higher extraction yields and tocopherol contents; the tocopherol content was also positively correlated with the antioxidant capacity of the lipophilic fraction, but the difference in the total phenolic content between the two genotypes was not significant. The SOBs derived from the high-protein soybeans were more easily oxidized during storage, with 1.38- and 4-fold higher accumulation rates of lipid hydroperoxides (LPO) and thiobarbituric acid reactive substances (TBARS), respectively, in the high-protein-derived SOBs than in the high-oil-derived SOBs. In addition, the SOBs from the high-protein soybeans exhibited pronounced coalescence during storage, which was corroborated by focused confocal microscopy. These results confirmed that SOBs obtained from high-oil soybean genotypes are more suitable to manufacture OB-based products due to their superior physicochemical stability.

Effect of alkyl chain length on the antioxidant activity of alkylresorcinol homologues in bulk oils and oil-in-water emulsions.

The antioxidant cut-off theory details the importance of fine-tuning antioxidant hydrophobicity to optimize antioxidant effectiveness for a given food system; however, previous research has utilized synthetic antioxidant homologues which fail to align with the food industry's demand for natural ingredients. Alkylresorcinols represent a natural homologous series of phenolipid antioxidants. The antioxidant activities of individual alkylresorcinol homologues were investigated in bulk oils and oil-in-water emulsions. In oils, antioxidant activity decreased as alkyl chain length increased and there was no effect on rate of loss. In emulsions, optimum antioxidant activity was observed at intermediate alkyl chain length (C21:0) and longer homologues were lost more rapidly. Radical scavenging capacity decreased as alkyl chain length increased but alkylresorcinols were unable to chelate iron. This suggests that intrinsic properties (e.g. radical scavenging capacity) are responsible for the antioxidant activity of alkylresorcinols in oils while physicochemical phenomena (e.g. partitioning) drive antioxidant activity of alkylresorcinols in emulsions.

Influences of encapsulated polyphosphate incorporation on oxidative stability and quality characteristics of ready to eat beef Döner kebab during storage.

The effect of different polyphosphates (sodium tripolyphosphate, STP; sodium hexametaphosphate, HMP; sodium pyrophosphate, SPP) and ratios of unencapsulated (u) and encapsulated (e) forms of these polyphosphates (PP, 0.5%) on lipid oxidation inhibition and quality characteristics of ground beef döner kebab were evaluated. STP usage provided lower cooking loss (CL) than HMP or SPP (P < .05). Döners containing STP had higher pH than those with HMP or SPP (P < .05). Regardless of ePP ratio in the total added PP (0.5%), added ePP created the same effect on CL and pH as 0.5% uPP in döner samples. The highest orthophosphate (OP) was obtained with STP, followed by SPP, HMP and control (no PP; P < .05). OP values generally decreased with increasing ePP ratio up to 0.4% in the total added PP (P < .05). Thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxide (LPO) in döners containing PP were lower than control (P < .05). The lowest TBARS and LPO were determined in döners containing STP or SPP (P < .05). In general, increasing ePP ratio (up to 0.2% for STP and SPP, and 0.4% for HMP) in the total added PP provided further reduction in TBARS and LPO (P < .05). TBARS and LPO results suggested that ePP incorporation may be strategic implementation for meat industry to control lipid oxidation in ready to eat döner kebab.

Aging and low-intensity exercise change oxidative biomarkers in brain regions and radiographic measures of femur of Wistar rats.

We investigated changes in oxidative biomarkers in brain regions such as brainstem, cerebellum, and cerebral cortex of 3-, 6-, 18-, 24-, and 30-month-old rats. We also assessed the effects of low-intensity exercise on these biomarkers in these regions of 6-, 18-, and 24-month-old rats that started exercise on a treadmill at 3, 15, and 21 months of age, respectively. Radiographic images of the femur were taken for all rats. A total of 25 rats (age: twelve 6-, ten 18-, ten 24-, and three 30-month-old rats) were used. Lipid hydroperoxide levels increased in cerebellum at 18 months. Total antioxidant activity exhibited lowest values in brainstem at 3 months. Superoxide dismutase activity did not exhibit significant changes during aging. Total thiol content exhibited lowest values in brain regions of 24- and 30-month-old rats. Exercise reduced total thiol content in brainstem at 6 months, but no change occurred in other regions and other ages. Femur increased its length and width and cortical thickness with advancing age. No change occurred in medullary width. Radiolucency increased and sclerosis was found in cortical and medullary bone with advancing age. Exercise reduced radiolucency and medullary sclerosis. Therefore, aging differentially changed oxidative biomarkers in different brain regions and radiographic measures of the femur. Low-intensity exercise only ameliorated some radiographic measurements of femur. Since the present study possessed limitations (small number of rats per group), a beneficial effect of regular low-intensity exercise on oxidative markers in brain cannot be ruled out.

Identification of cadmium-produced lipid hydroperoxides, transcriptomic changes in antioxidant enzymes, xenobiotic transporters, and pro-inflammatory markers in human breast cancer cells (MCF7) and protection with fat-soluble vitamins.

Cadmium (Cd) is a toxic metal that is regarded as a metallohormone with estrogen-like properties. The present study aimed at identification of lipid hydroperoxides produced in human breast cancer (MCF7) exposed to cadmium (Cd) at environmentally relevant levels. Cd induced cytotoxicity and oxidative stress and produced a series of 26 lipid hydroperoxide species including 14 phosphatidylcholine hydroperoxides (PC-OOH), 9 triacylglycerol hydroperoxides (TG-OOH), and 3 cholesteryl ester hydroperoxides (CE-OOH). Among these hydroperoxides, PC34:2-OOH, PC34:3-OOH, TG60:14-OOH, TG48:5-OOH, TG60:15-OOH, and CE20:4-OOH were produced in a dose-dependent manner, suggesting these as possible biomarkers for Cd exposure in MCF7 cells. In addition, Cd led to significant decreases in the gene expressions of antioxidants, detoxification enzymes, and xenobiotic transporters. In a protection trial, co-exposure of MCF7 cells to fat-soluble vitamins including vitamin A, D, and E reduced Cd-induced cytotoxicity, lipid peroxidation, oxidative stress, and inflammatory responses. Fat-soluble vitamins upregulated antioxidant and detoxification enzymes, and xenobiotic transporters. Therefore, dietary supplementation of such micronutrients is recommended for people at risk for exposure to Cd.

Aging and low-intensity exercise change oxidative biomarkers in brain regions and radiographic measures of femur of Wistar rats

We investigated changes in oxidative biomarkers in brain regions such as brainstem, cerebellum, and cerebral cortex of 3-, 6-, 18-, 24-, and 30-month-old rats. We also assessed the effects of low-intensity exercise on these biomarkers in these regions of 6-, 18-, and 24-month-old rats that started exercise on a treadmill at 3, 15, and 21 months of age, respectively. Radiographic images of the femur were taken for all rats. A total of 25 rats (age: twelve 6-, ten 18-, ten 24-, and three 30-month-old rats) were used. Lipid hydroperoxide levels increased in cerebellum at 18 months. Total antioxidant activity exhibited lowest values in brainstem at 3 months. Superoxide dismutase activity did not exhibit significant changes during aging. Total thiol content exhibited lowest values in brain regions of 24- and 30-month-old rats. Exercise reduced total thiol content in brainstem at 6 months, but no change occurred in other regions and other ages. Femur increased its length and width and cortical thickness with advancing age. No change occurred in medullary width. Radiolucency increased and sclerosis was found in cortical and medullary bone with advancing age. Exercise reduced radiolucency and medullary sclerosis. Therefore, aging differentially changed oxidative biomarkers in different brain regions and radiographic measures of the femur. Low-intensity exercise only ameliorated some radiographic measurements of femur. Since the present study possessed limitations (small number of rats per group), a beneficial effect of regular low-intensity exercise on oxidative markers in brain cannot be ruled out.

Identification of lead-produced lipid hydroperoxides in human HepG2 cells and protection using rosmarinic and ascorbic acids with a reference to their regulatory roles on Nrf2-Keap1 antioxidant pathway.

Lead (Pb) is one of the toxic heavy metals that have several toxicological implications including cytotoxicities and oxidative stress. The release of reactive oxygen species (ROS) usually initiates lipid peroxidation and resulting in inflammation and tissue injury. However, the detailed identification of the Pb-produced lipid hydroperoxides has received little attention. Furthermore, the mechanisms behind such effects are less informed. Therefore, this study firstly investigated Pb-produced lipid hydroperoxides in human HepG2 cells using LC/MS. The effects of Pb on the antioxidant enzymes were additionally examined using qPCR and their dependent activities. As a protection trial, the ameliorative effects of rosmarinic (RMA) and ascorbic (ASA) acids on Pb-induced cytotoxicity and oxidative stress and their regulatory effects on Nrf2/Keap1 pathway were investigated. The achieved results confirmed cytotoxicity and oxidative damage of Pb on HepG2 cells. In addition, 20 lipid hydroperoxides (LOOH) were identified including 11 phosphatidylcholine hydroperoxides (PCOOH), 5 triacylglycerol hydroperoxides (TGOOH) and 4 cholesteryl ester hydroperoxides (CEOOH). The most dominant LOOH species were PCOOH 34:2, PCOOH 34:3, PCOOH 38:7, TGOOH 60:14, TGOOH 60:15, CEOOH 18:3 and CEOOH 20:4. Pb significantly downregulated Nrf2-regulated antioxidant enzymes at both the pretranscriptional and functional levels. Co-exposure of HepG2 cells to RMA and ASA significantly reduced Pb-produced adverse outcomes. This protection occurred via activation Nrf2-Keap1 antioxidant pathway.

Oxidative Stress Markers and Severity of Obstructive Sleep Apnea.

Oxidative stress underlies both obstructive sleep apnea (OSA) and atherosclerosis. The aim of the study was to assess the markers of oxidative stress in plasma at different stages of OSA in non-smoking obese Caucasian males aged 41-60, with normal oral glucose tolerance test. All patients were subjected to clinical and polysomnographic examinations. The stage of OSA severity was set according to the following criteria of the apnea-hypopnea index (AHI): AHI < 5/h - no disease (OSA-0; n = 26), AHI 5-15/h - mild disease (OSA-1; n = 26), AHI 16-30/h - moderate disease (OSA-2: n = 27), and AHI > 30/h obstructive episodes per hour - severe disease (OSA-3; n = 27). Plasma total antioxidant status (TAS) and thiobarbituric acid-reacting substances (TBARS), reflecting the level of lipid peroxides, were determined spectrophotometrically. We found that TAS decreased and TBARS increased significantly from OSA-0 to OSA-3. We conclude that the oxidative stress markers are conducive to setting the severity of OSA in normoglycemic patients.

[Saliva as highly informative substrate for non-invasive analysis of lipoperoxide processes and muscle damage in highly skilled athletes.]

The purpose of the investigation was to study the efficiency of measuring markers of oxidative stress and muscle damage in the oral fluid in highly skilled sportsmen under physical exercise for the assessment of their functional state. 70 highly qualified athletes at the age of 16-20 years specializing in the cyclic kinds of sports (track and field, swimming) took part in the investigation. Sportsmen performed the control test which consisted of the series of 3×100 m distances by a flat race with an active 45 s rest between them for the track and field athletes, and 4×50 m by the main swimming style with an active rest between the distances also for 45 s for the swimmers. Activity of creatine kinase, content of lipid peroxidation products in the blood and oral fluid were measured standard biochemical methods. The performance of the functional tests induces the excessive accumulation of toxic products of lipoperoxidation and increases activity of creatine kinase in the oral fluid of highly qualified athletes. Correlation analysis shows, that the intensity of free radical and peroxide processes in athletes can be evaluated by means of the method of measuring the content of lipid peroxidation products in the oral fluid.

Evaluation of lipid oxidation mechanisms in beverages and cosmetics via analysis of lipid hydroperoxide isomers.

Understanding of lipid oxidation mechanisms (e.g., auto-oxidation and photo-oxidation) in foods and cosmetics is deemed essential to maintain the quality of such products. In this study, the oxidation mechanisms in foods and cosmetics were evaluated through analysis of linoleic acid hydroperoxide (LAOOH) and linoleic acid ethyl ester hydroperoxide (ELAOOH) isomers. Based on our previous method for analysis of LAOOH isomers, in this study, we developed a new HPLC-MS/MS method that enables analysis of ELAOOH isomers. The HPLC-MS/MS methods to analyze LAOOH and ELOOH isomers were applied to food (liquor) and cosmetic (skin cream) samples. As a result, LAOOH and ELAOOH isomers specific to photo-oxidation, and ELAOOH isomers characteristic to auto-oxidation were detected in some marketed liquor samples, suggesting that lipid oxidation of marketed liquor proceeds by both photo- and auto-oxidation during the manufacturing process and/or sales. In contrast, because only LAOOH and ELAOOH isomers specific to auto-oxidation were detected in skin cream stored under dark at different temperatures (-5 °C-40 °C) for different periods (2-15 months), auto-oxidation was considered to be the major oxidation mechanism in such samples. Therefore, our HPLC-MS/MS methods appear to be powerful tools to elucidate lipid oxidation mechanisms in food and cosmetic products.

Avaliação de propriedades funcionais e oxidação lipídica em mortadela com aplicação de maca peruana / Evaluation of functional properties and lipid oxidation in mortadella with application of maca peruana

Avaliou-se durante 90 dias o pH, a cor, a capacidade de retenção de água (CRA), a textura e a oxidação lipídica, de uma formulação de mortadela otimizada por meio de um delineamento experimental de mistura para dois componentes. Desenvolveram-se duas amostras da formulação de mortadela otimizada, com antioxidante (OA) e sem antioxidante (OS). Os valores de pH e CRA não apresentaram diferenças significativas ao final dos 90 dias entre as amostras, OA (6,02 e 94,05 g/100g) e OS (6,07 e 93,25 g/100g). Na cor houve diferenças significativas. Na textura, apenas a dureza, mastigabilidade e coesividade apresentaram diferenças significativas. E aos 90 dias as amostras com (2,10 mg de MDA/Kg) e sem antioxidante (2,59 mg de MDA/Kg) não apresentaram diferenças significativas para oxidação lipídica e podem ser considerados aceitáveis para produtos cárneos.

Efeito da adição de óleo essencial de Origanum vulgar e Ocimum gratissimum L. no perfil lipídico da gordura de palma usada em fritura de batata tipo chips / Palm oil fatty acid profile evaluation during the potato chips processing with Origanum vulgar and Ocimum gratissimum L

O objetivo deste trabalho foi avaliar o efeito antioxidante dos óleos essenciais de orégano e alfavacão sobre a estabilidade e perfil de ácidos graxos da gordura de palma utilizada no processamento industrial. Foram adicionados 100ug.g-1 de óleos essenciais em gordura de palma, que foi submetida a onze ciclos de fritura de batatas tipo chips. Amostras da gordura submetidas ao processamento foram analisadas quanto às características físico-químicas e perfil de ácidos graxos. Nas condições do estudo, não foi observado efeito dos óleos essenciais sobre a inibição na formação de compostos trans. Não houve alteração da relação de ácidos graxos poli-insaturados e ácidos graxos saturados da gordura. No entanto, a análise de peróxido indicou um efeito positivo do óleo essencial de alfavacão na redução da formação de radicais livres.

Lipidomic methodologies for biomarkers of chronic inflammation in nutritional research: ω-3 and ω-6 lipid mediators.

The evolutionary history of hominins has been characterized by significant dietary changes, which include the introduction of meat eating, cooking, and the changes associated with plant and animal domestication. The Western pattern diet has been linked with the onset of chronic inflammation, and serious health problems including obesity, metabolic syndrome, and cardiovascular diseases. Diets enriched with ω-3 marine PUFAs have revealed additional improvements in health status associated to a reduction of proinflammatory ω-3 and ω-6 lipid mediators. Lipid mediators are produced from enzymatic and non-enzymatic oxidation of PUFAs. Interest in better understanding the occurrence of these metabolites has increased exponentially as a result of the growing evidence of their role on inflammatory processes, control of the immune system, cell signaling, onset of metabolic diseases, or even cancer. The scope of this review has been to highlight the recent findings on: a) the formation of lipid mediators and their role in different inflammatory and metabolic conditions, b) the direct use of lipid mediators as antiinflammatory drugs or the potential of new drugs as a new therapeutic option for the synthesis of antiinflammatory or resolving lipid mediators and c) the impact of nutritional interventions to modulate lipid mediators synthesis towards antiinflammatory conditions. In a second part, we have summarized methodological approaches (Lipidomics) for the accurate analysis of lipid mediators. Although several techniques have been used, most authors preferred the combination of SPE with LC-MS. Advantages and disadvantages of each method are herein addressed, as well as the main LC-MS difficulties and challenges for the establishment of new biomarkers and standardization of experimental designs, and finally to deepen the study of mechanisms involved on the inflammatory response.

Ischemic Preconditioning Preserves Liver Energy Charge and Function on Hepatic Ischemia/Reperfusion Injury in Rats.

BACKGROUND: Cell energy during ischemia/reperfusion depends on mechanisms including adenosine diphosphate degradation, oxygen species and cytokine liberation, neutrophil infiltration, and endothelial dysfunction. Preconditioning-a brief ischemic episode that confers a state of protection against subsequent ischemia-reperfusion injury-involves NO and adenosine production, reduction in oxygen species liberation, and preservation of microcirculation. During hypoxia, constitutive NO production assures adequate oxygen delivery and reduced energy loss. The aim was to determine the role of ischemic preconditioning in the stimulation of constitutive endothelial nitric oxide (NO) production and its effect on energy charge, radical oxygen species generation, cytokine liberation, and neutrophil infiltration during reperfusion. MATERIALS AND METHODS: Rats were assigned to one of four groups depending on the preconditioning protocol: hepatic ischemia/reperfusion, or hepatic ischemia/reperfusion and ischemic preconditioning, for 5, 10, or 20 min. A portosystemic shunt was established between the portal and left jugular veins during ischemia. RESULTS: Preconditioning produced rises in plasma nitrites, but no rise in inducible nitric oxide synthase gene expression. A 5 or 10 min preconditioning period allowed for higher energy charge, bile production, and glutathione levels, with less lipoperoxide, alanine aminotransferase, tumor necrosis factor-α, and interleukin-1 production and neutrophil infiltration, compared with 20 min or control. Survival was 80% in the G10 group, 70 in G5, 10 in GC, and 0% in the G20 group. CONCLUSIONS: Ten-min liver preconditioning improves survival and prevents energy loss during hepatic ischemia/reperfusion by stimulating constitutive NO production, maintaining glutathione concentrations and reducing oxygen species and proinflammatory cytokine generation as well as neutrophil infiltration.

Use of straw mushrooms (Volvariella volvacea) for the enhancement of physicochemical, nutritional and sensory profiles of Cantonese sausages.

The aim of this work was to evaluate the quality and sensory properties of Cantonese sausages incorporated with dried straw mushrooms. Five types of sausage with the addition of 0%, 1%, 2%, 3%, and 4% straw mushrooms were prepared, and their physicochemical traits and sensory acceptance were investigated. The results showed that incorporation of straw mushrooms improved the physical properties, significantly decreased peroxide value, increased the amount of amino acids and volatile compounds, and introduced new volatiles (aldehyde and ester compounds) to Cantonese sausages. Compared to sausages without addition of straw mushrooms, the amount of essential amino acids increased 8-fold, the P/S ratio of fatty acid increased to 0.46 similar to the recommended nutritional value, and the lipid peroxide value reduced 10-fold in Cantonese sausages with addition of 4% straw mushrooms. These results indicate that incorporation of straw mushrooms could be an efficient way to obtain nutritional and healthy Cantonese sausages.

Serum and hepatic oxidative damage induced by a diet contaminated with fungal mycotoxin in freshwater silver catfish Rhamdia quelen: Involvement on disease pathogenesis.

It has been recognized that oxidative stress is implicated in the initiation and progression of diseases due to the excessive formation of free radicals and impairment of the antioxidant defense system, contributing to the mortality of affected animals. The occurrence of a disequilibrium between the antioxidant/oxidant status in serum and liver of freshwater fish fed with aflatoxin B1 (AFB1) remains poorly understood and limited to only a few oxidant variables. Thus, the aim of this study was to evaluate whether an AFB1-contaminated diet causes disturbance on the antioxidant and oxidant status in silver catfish (Rhamdia quelen) of freshwater. Serum and hepatic reactive oxygen species (ROS), metabolites of nitric oxide (NOx), and lipid hydroperoxide increased on days 14 and 21 post-feeding in animals that received AFB1 contaminated diet compared to the control group (basal diet), while protein carbonylation levels increased on day 21 post-feeding. On the other hand, serum and hepatic antioxidant capacity against peroxyl radical and vitamin C levels, as well as glutathione peroxidase and catalase activities were lower on days 14 and 21 post-feeding in animals that received AFB1 contaminated diet compared to the control group. No difference was observed between groups regarding the superoxide dismutase activity and glutathione levels. Based on these evidences, an AFB1-contaminated diet causes a disturbance on serum and hepatic antioxidant/oxidant system due to lipid and protein damage elicited by excessive ROS and NOx production. Also, the antioxidant defense system was unable to avoid or minimize ROS and NOx deleterious effects, and consequently, the oxidative damage. In summary, this disturbance can contribute to understand the pathophysiology and mortality of fish after the consumption of AFB1-contaminated diets.

Rapid Quantitative Profiling of Lipid Oxidation Products in a Food Emulsion by 1H NMR.

Lipid oxidation is one of the most important reasons for the compromised shelf life of food emulsions. A major bottleneck in unravelling the underlying mechanisms is the lack of methods that provide a rapid, quantitative, and comprehensive molecular view on lipid oxidation in these heterogeneous systems. In this study, the unbiased and quantitative nature of 1H NMR was exploited to assess lipid oxidation products in mayonnaise, a particularly oxidation-prone food emulsion. An efficient and robust procedure was implemented to produce samples where the 1H NMR signals of oxidation products could be observed in a well resolved and reproducible manner. 1H NMR signals of hydroperoxides were assigned in a fatty acid and isomer specific way. Band-selective 1H NMR pulse excitation allowed immediate and precise (RSDR = 5.9%) quantification of both hydroperoxides and aldehydes with high throughput and large dynamic range at levels of 0.03 mmol/kg. Explorative multivariate data modeling of the quantitative 1H NMR profiles revealed that shelf life temperature has a significant impact on lipid oxidation mechanisms.

Association of serum bilirubin with oxidant damage of human atherosclerotic plaques and the severity of atherosclerosis.

Bilirubin has protective effects against atherosclerotic cardiovascular diseases hypothetically due to its antioxidant-antilipoperoxidative properties. Thus, we investigated whether serum bilirubin is associated with oxidant damage, namely lipid peroxidation, of human atherosclerotic plaques and the severity of atherosclerosis. In this regard, we correlated the levels of serum total bilirubin (STB), direct (conjugated) bilirubin (SDB) and indirect (unconjugated) bilirubin (SIB) with those of fluorescent damage products of lipid peroxidation (FDPL) and lipid hydroperoxides (LOOH) of 32 endarterectomy-derived carotid atherosclerotic plaques. Moreover, we compared the levels of serum bilirubin and plaque lipoperoxides between two groups of patients of the study population with different severity of atherosclerosis as judged by the carotid stenosis degree, i.e., <90% (group A, n = 23) and ≥90% (group B, n = 9). Remarkably, the levels of STB were strongly inversely correlated with those of plaque FDPL (rS = -0.70, P < 0.0001) and LOOH (rS = -0.66, P < 0.0001), as were those of SIB (FDPL: rS = -0.68, P < 0.0001; LOOH: rS = -0.63, P < 0.0001). SDB had a weaker association with plaque FDPL (rS = -0.41, P < 0.05) and LOOH (rS = -0.35, P < 0.05). Moreover, the levels of STB, SDB and SIB were lower and those of plaque lipoperoxides higher in group B than in group A, pointing to the association of serum bilirubin and plaque oxidant burden with the severity of atherosclerosis. In conclusion, lowered serum bilirubin is associated with oxidant damage of human atherosclerotic plaques and the severity of atherosclerosis.