Digestive interaction between dietary nitrite and dairy products generates novel nitrated linolenic acid products

Nitrated fatty acids are important anti-inflammatory and protective lipids formed in the gastric compartment, with conjugated linoleic acid (rumenic acid, RA, 9Z,11E-18:2) being the primary substrate for lipid nitration. The recently reported identification of nitrated rumelenic acid (NO2-RLA) in human urine has led to hypothesize that rumelenic acid (RLA, 9Z,11E,15Z-18:3) from dairy fat is responsible for the formation of NO2-RLA. To evaluate the source and mechanism of NO2-RLA formation, 15N labeled standards of NO2-RLA were synthesized and characterized. Afterward, milk fat with different RA and RLA levels was administered to mice in the presence of nitrite, and the appearance of nitrated fatty acids in plasma and urine followed. We confirmed the formation of NO2-RLA and defined the main metabolites in plasma, urine, and tissues. In conclusion, RLA obtained from dairy products is the main substrate for forming this novel electrophilic lipid reported to be present in human urine.

Engineering Yarrowia lipolytica for Sustainable Production of the Pomegranate Seed Oil-Derived Punicic Acid

Punicic acid is a conjugated linolenic acid with various biological activities including antiobesity, antioxidant, anticancer, and anti-inflammatory effects. It is often used as a nutraceutical, dietary additive, and animal feed. Currently, punicic acid is primarily extracted from pomegranate seed oil, but it is restricted due to the extended growth cycle, climatic limitations, and low recovery level. There have also been reports on the chemical synthesis of punicic acid, but it resulted in a mixture of structurally similar isomers, requiring additional purification/separation steps. In this study, a comprehensive strategy for the production of punicic acid in Yarrowia lipolytica was implemented by pushing the supply of linoleic acid precursors in a high-oleic oil strain, expressing multiple copies of the fatty acid conjugase gene from Punica granatum, engineering the acyl-editing pathway to improve the phosphatidylcholine pool, and promoting the assembly of punicic acid in the form of triglycerides. The optimal strain with high oil production capacity and a significantly increased punicic acid ratio accumulated 3072.72 mg/L punicic acid, accounting for 6.19% of total fatty acids in fed-batch fermentation, providing a viable, sustainable, and green approach for punicic acid production to substitute plant extraction and chemical synthesis production.

Profile change of the volatile and non-volatile compounds in dried or baked laver by photooxidation

Effects of light or dark storage condition on the profile changes of volatile and non-volatile compounds were evaluated in dried and baked laver for 60 days. Volatile and non-volatile compounds were analyzed using gas chromatography-mass selective detection and high-performance liquid chromatography-quadrupole-time of flight-mass spectrometry, respectively. Baked laver stored in light conditions for 60 days produced the most volatile compounds, whereas dried laver stored in the dark produced the least volatile compounds. Total 11 classes of volatile compounds were detected, including alkanes, alkenes, and ketones, with aldehydes being most abundant in dried laver stored under light. Metabolite analysis of non-volatile compounds led to the selection of 12 compounds with a higher variable importance projection (VIP) value of >1.0: 6 fatty acids (VIP 1.2-2.0), 2 flavanols (VIP 1.3-1.8), hydroxybenzoic acid (VIP 1.5), hydroxycinnamic acid (VIP 2.3), a phenolic acid ester (VIP 1.9), and phloroglucinol (VIP 1.2). Generally, levels of these compounds decreased more following storage in the light than under dark, irrespective of laver preparation. The content of linolenic acid was particularly affected by storage conditions, with light conditions causing a fourfold reduction in linolenic acid level compared with dark conditions, which could result in an increased formation of aldehydes. Gallic acid and sinapinic acid were detected in dried but not baked laver, as they are destroyed by heat treatment. Therefore, laver should be baked and stored in dark conditions to prevent the development of rancidity. PRACTICAL APPLICATION: Laver is one of the representative seaweeds, and the popularity among consumers increases. Although commercially available laver is prepared in dried or baked condition, scientific studies on the changes of metabolites, including volatile and non-volatile compounds during storage, are scarce. The results of this study can be applied to improve proper storage methods to maintain the quality of laver, which can be beneficial for consumers and food industry.

Effect of edible oil type on the formation of protein-bound Nε-(carboxymethyl)lysine in roasted pork patties

Protein-bound Nε-(carboxymethyl)lysine (CML), an advanced glycation end product within meat products, poses a potential health risk to humans. The objective of this study was to explore the impact of various edible oils on the formation of protein-bound CML in roasted pork patties. Eleven commercially edible oils including lard oil, corn oil, palm oil, olive oil, flaxseed oil, blended oil, camellia oil, walnut oil, soybean oil, peanut oil, and colza oil were added to pork tenderloin mince, respectively, at a proportion of 4 % to prepare raw pork patties. The protein-bound CML contents in the pork patties were determined by HPLC-MS/MS before and after roasting at 200 °C for 20 min. The results indicated that walnut oil, flaxseed oil, colza oil, olive oil, lard oil, corn oil, blended oil, and palm oil significantly reduced the accumulation of protein-bound CML in pork patties, of which the inhibition rate was in the 24.43 %-37.96 % range. Moreover, the addition of edible oil contributed to a marginal reduction in the loss of lysine. Meanwhile, glyoxal contents in pork patties were reduced by 16.72 %-43.21 % after roasting. Other than blend oil, all the other edible oils restrained protein oxidation in pork patties to varying degrees (between 20.16 % and 61.26 %). In addition, camellia oil, walnut oil, and flaxseed oil increased TBARS values of pork patties by 2.2-8.6 times when compared to the CON group. After analyzing the fatty acid compositions of eleven edible oils, five main fatty acids (palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid) were selected to establish Myofibrillar protein-Glucose-fatty acids systems to simulate the roasting process. The results showed that palmitic acid, oleic acid, linoleic acid, and linolenic acid obviously mitigated the formation of myofibrillar protein-bound CML, exhibiting suppression rates ranging from 10.38 % to 40.32 %. In conclusion, the addition of specific edible oil may curb protein-bound CML production in roasted pork patty by restraining protein or lipid oxidation, reducing lysine loss, and suppressing glyoxal production, which may be attributed to the fatty acid compositions of edible oils. This finding provides valuable guidance for the selection of healthy roasting oils in the thermal processing of meat products.

Study on the thermal oxidation of oleic, linoleic and linolenic acids by synchrotron radiation photoionization mass spectrometry

RATIONALE

Cooking oil fumes contain numerous hazardous and carcinogenic chemicals, posing potential threats to human health. However, the sources of these species remain ambiguous, impeding health risk assessment, pollution control and mechanism research.

METHODS

To address this issue, the thermal oxidation of three common unsaturated fatty acids (UFAs), namely oleic, linoleic and linolenic acids, present in vegetable oils was investigated. The volatile and semi-volatile products were comprehensively characterized by online synchrotron radiation photoionization mass spectrometry (SR-PIMS) with two modes, which were validated and complemented using offline gas chromatography (GC)/MS methods. Tunable SR-PIMS combined with photoionization efficiency curve simulation enabled the recognition of isomers/isobars in gaseous fumes.

RESULTS

SR-PIMS revealed over 100 products, including aldehydes, alkenes, furans, aromatic hydrocarbons, etc., such as small molecules of formaldehyde, acetaldehyde, acrolein, ethylene and furan, which are not readily detected by conventional GC/MS; and some unreported fractions, e.g. ketene, 4-ethylcyclohexene and cycloundecene(E), were also observed. Furthermore, real-time monitoring of product emissions during the thermal oxidation of the three UFAs via SR-PIMS revealed that linolenic acid may be the major source of acrolein.

CONCLUSION

SR-PIMS has been demonstrated as a powerful technique for online investigation of cooking oil fumes. This study achieved comprehensive characterization of volatile and semi-volatile products from the thermal oxidation of oleic, linoleic and linolenic acids, facilitating the traceability of species in cooking fumes and aiding in exploring the thermal reactions of different vegetable oils.

Correlation between immune-related Tryptophan-Kynurenine pathway and severity of severe pneumonia and inflammation-related polyunsaturated fatty acids

BACKGROUND

Immune dysfunction and oxidative stress caused by severe pneumonia can lead to multiple organ dysfunction and even death, causing a significant impact on health and the economy. Currently, great progress has been made in the diagnosis and treatment of this disease, but the mortality rate remains high (approximately 50%). Therefore, there is still potential for further exploration of the immune response mechanisms against severe pneumonia.

OBJECTIVE

This study analyzed the difference in serum metabolic profiles between patients with severe pneumonia and health individuals through metabolomics, aiming to uncover the correlation between the Tryptophan-Kynurenine pathway and the severity of severe pneumonia, as well as N-3/N-6 polyunsaturated fatty acids (PUFAs).

METHODS

In this study, 44 patients with severe pneumonia and 37 health controls were selected. According to the changes in the disease symptoms within the 7 days of admission, the patients were divided into aggravation (n = 22) and remission (n = 22) groups. Targeted metabolomics techniques were performed to quantify serum metabolites and analyze changes between groups.

RESULTS

Metabolomics analysis showed that serum kynurenine and kynurenine/tryptophan (K/T) were significantly increased and tryptophan was significantly decreased in patients with severe pneumonia; HETE and HEPE in lipids increased significantly, while eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), α-linolenic acid (linolenic acid, α-LNA), arachidonic acid (ARA), Dihomo-γ-linolenic acid (DGLA), and 13(s)-hydroperoxylinoleic acid (HPODE) decreased significantly. Additionally, the longitudinal comparison revealed that Linolenic acid, DPA, and Tryptophan increased significantly in the remission group, while and kynurenine and K/T decreased significantly. In the aggravation group, Kynurenine and K/T increased significantly, while ARA, 8(S)-hydroxyeicosatetraenoic acid (HETE), 11(S)-HETE, and Tryptophan decreased significantly. The correlation analysis matrix demonstrated that Tryptophan was positively correlated with DGLA, 12(S)-hydroxyeicosapentaenoic acid (HEPE), ARA, EPA, α-LNA, DHA, and DPA. Kynurenine was positively correlated with 8(S)-HETE and negatively correlated with DHA. Additionally, K/T was negatively correlated with DGLA, ARA, EPA, α-LNA, DHA, and DPA.

CONCLUSION

This study revealed that during severe pneumonia, the Tryptophan-Kynurenine pathway was activated and was positively correlated with the disease progression. On the other hand, the activation of the Tryptophan-Kynurenine pathway was negatively correlated with N-3/N-6 PUFAs.

Changes in Chemical Composition of Flaxseed Oil during Thermal-Induced Oxidation and Resultant Effect on DSC Thermal Properties

To investigate the changes in chemical composition of flaxseed oil during thermal-induced oxidation and the resultant effect on thermal properties, samples with different oxidation levels were obtained by being heated at 180 °C for two hours and four hours. The oxidation degree was evaluated using peroxide value (PV), extinction coefficient at 232 nm and 268 nm (K232 and K268), and total polar compounds (TPC). Using chromatography, the fatty acid profile and triacylglycerol (TAG) profile were examined. Differential scanning calorimetry (DSC) was used to determine the crystallization and melting profiles. Thermal-induced oxidation of flaxseed oil led to a significant increase (p < 0.05) in PV, K232, K268, and TPC, but the relative content of linolenic acid (Ln) and LnLnLn reduced dramatically (p < 0.05). TPC derived from lipid degradation affected both crystallization and melting profiles. Statistical correlations showed that the onset temperature (Ton) of the crystallization curve was highly correlated with K232, TPC, and the relative content of LnLnLn (p < 0.05), whereas the offset temperature (Toff) of the melting curve was highly correlated with the relative content of most fatty acids (p < 0.05). This finding provides a new way of rapid evaluation of oxidation level and changes of chemical composition for flaxseed oils using DSC.

Systematical Ingredient Investigations of Ficus tikoua Bur. Fruit and Immunoregulatory and Antioxidant Effects of Different Fractions

Although the fruit of Ficus tikoua Bur. has been consumed by montanic people in China for centuries, its chemical and biological composition was still unclear. A series of comprehensive investigations on its chemical constituents and bioactivities were carried out for the first time. As a result, six compounds were isolated and identified as the main components in this fruit. GC-MS analysis of the lipid components demonstrated that Ficus tikoua Bur. fruit contains some wholesome constituents such as fatty acids, vitamins, triterpenoids, and phytosterols. The fatty acids are mainly composed of linolenic acid (61.27%) and linoleic acid (22.79%). Furthermore, this fruit contains a relative high content of crude protein (9.41 ± 0.03%), total amino acids (9.28%), and total polyphenols (0.86 ± 0.01 g/100 g). The analysis of monosaccharide composition showed that the total polysaccharide mainly consists of glucose, glucuronic acid, xylose, arabinose, mannose, galactose, galacturonic acid, and rhamnose. The polysaccharide, polyphenol, water, ethanol, and flavonoid extracts exhibited prominent antioxidant activity determined by ABTS, DPPH, and FRAPS methods. Meanwhile, the total polysaccharide exhibited significant immunomodulatory effect by enhancing the release of cytokines and expression of iNOS and COX-2 in RAW264.7 cells, significantly decreasing the expression of c-Jun and p65 proteins in the cytoplasm; increasing the translocation of c-Jun and p65 to the nucleus; and regulating the phosphorylation level of Akt, PI3K, and PDK1 in the PI3K/AKT signaling pathway. This study proved that the fruit of F. tikoua is a reliable source of functional food.

Genome-Wide Characterization and Expression Analysis of Fatty acid Desaturase Gene Family in Poplar

Fatty acid desaturases (FADs) modulate carbon–carbon single bonds to form carbon–carbon double bonds in acyl chains, leading to unsaturated fatty acids (UFAs) that have vital roles in plant growth and development and their response to environmental stresses. In this study, a total of 23 Populus trichocarpaFAD (PtFAD) candidates were identified from the poplar genome and clustered into seven clades, including FAB2, FAD2, FAD3/7/8, FAD5, FAD6, DSD, and SLD. The exon–intron compositions and conserved motifs of the PtFADs, clustered into the same clade, were considerably conserved. It was found that segmental duplication events are predominantly attributable to the PtFAD gene family expansion. Several hormone- and stress-responsive elements in the PtFAD promoters implied that the expression of the PtFAD members was complicatedly regulated. A gene expression pattern analysis revealed that some PtFAD mRNA levels were significantly induced by abiotic stress. An interaction proteins and gene ontology (GO) analysis indicated that the PtFADs are closely associated with the UFAs biosynthesis. In addition, the UFA contents in poplars were significantly changed under drought and salt stresses, especially the ratio of linoleic and linolenic acids. The integration of the PtFAD expression patterns and UFA contents showed that the abiotic stress-induced PtFAD3/7/8 members mediating the conversion of linoleic and linolenic acids play vital roles in response to osmotic stress. This study highlights the profiles and functions of the PtFADs and identifies some valuable genes for forest improvements.

Improving the Production of Punicic Acid in Baker's Yeast by Engineering Genes in Acyl Channeling Processes and Adjusting Precursor Supply

Punicic acid (PuA) is a high-value edible conjugated fatty acid with strong bioactivities and has important potential applications in nutraceutical, pharmaceutical, feeding, and oleochemical industries. Since the production of PuA is severely limited by the fact that its natural source (pomegranate seed oil) is not readily available on a large scale, there is considerable interest in understanding the biosynthesis and accumulation of this plant-based unusual fatty acid in transgenic microorganisms to support the rational design of biotechnological approaches for PuA production via fermentation. Here, we tested the effectiveness of genetic engineering and precursor supply in PuA production in the model yeast strain Saccharomyces cerevisiae. The results revealed that the combination of precursor feeding and co-expression of selected genes in acyl channeling processes created an effective "push-pull" approach to increase PuA content, which could prove valuable in future efforts to produce PuA in industrial yeast and other microorganisms via fermentation.

Fat regulatory mechanisms of pine nut oil based on protein interaction network analysis

BACKGROUND

Pine nut oil (PNO), a standardized and well-defined extract of Pinus koraiensis (Korean pine), has beneficial effects on wound healing, inflammatory diseases, and cancer. However, the explanation for the mechanism by which PNO reduces body fat remains uncertain. We performed a protein-protein interaction network (PPIN) analysis to explore the genes associated with pinolenic acid using the MEDILINE database from PubChem and PubMed. It was concluded through the PPIN analysis that PNO was involved in a neutral lipid biosynthetic process.

PURPOSE

This study evaluated the effects of PNO predicted by the network analysis of fat accumulation in chronic obesity mouse models established by feeding a high fat diet (HFD) to C57BL/6J mice and explored potential mechanisms.

METHODS

HFD mice were fed only HFD or HFD with PNO at 822 and 1644 mg/kg. After an oral administration of 7 weeks, several body weight and body fat-related parameters were examined, including the following: adipose weight, adipocyte size, serum lipid profiles, adipocyte expression of PPAR-γ, sterol regulatory element binding protein (SREBP)-1c, lipoprotein lipase (LPL) and leptin.

RESULTS

We showed that oral administration of PNO to HFD mice reduces body fat weight, fat in tissue, white adipose tissue weight, and adipocyte size. The serum cholesterol was improved in the HFD mice treated with PNO. Additionally, PNO has significantly attenuated the HFD-induced changes in the adipose tissue expression of PPAR-γ, SREBP-1c, LPL, and leptin.

CONCLUSIONS

The findings from this study based on the PPIN analysis suggest that PNO has potential as drug to reduce body fat through fat regulatory mechanisms by PPAR-γ and SREBP-1c.

Conjugated Fatty Acids in Muscle Food Products and Their Potential Health Benefits: A Review

Conjugated fatty acids (CFAs) are a group of positional and geometric isomers of polyunsaturated fatty acids (PUFAs) with conjugated double bonds. There are several subgroups of CFAs including conjugated linoleic acids (CLAs), conjugated linolenic acids (CLNAs), conjugated eicosapentaenoic acids (CEPAs), and conjugated docosahexaenoic acids (CDHAs). CFAs, especially CLAs, have been studied in recent years both for their health benefits and factors that affect their level in muscle food products. CFAs have been reported in numerous studies as having antitumor, antiobesity, antidiabetes, anticardiovascular disease, and modulating immune system effects. These biological activies are involved in changes of lipid peroxidation and energy expenditure, as well as inhibitory effects on the hormone receptor, lipid metabolism, lipoprotein lipase activity, and adiponectin production. A large body of studies has revealed that the diet, processing, storage conditions, slaughter season, and age are common factors that affect CFA content in muscle food products, as detailed in this review. Recommendations are made regarding animal farming and meat product processing to obtain high CFA content meat products and to optimize the benefits of CFA for health promotion.

Punicic acid production in Brassica napus

Punicic acid (PuA; 18:3Δ^{9cis,11trans,13cis}), a conjugated linolenic acid isomer bearing three conjugated double bonds, is associated with various health benefits and has potential for industrial use. The major nature source of this unusual fatty acid is pomegranate (Punica granatum) seed oil, which contains up to 80% (w/w) of its fatty acids as PuA. Pomegranate seed oil, however, is low yielding with unstable production and thus limits the supply of PuA. Metabolic engineering of established temperate oil crops for PuA production, therefore, has the potential to be a feasible strategy to overcome the limitations associated with sourcing PuA from pomegranate. In this study, the cDNAs encoding a pomegranate fatty acid conjugase and a pomegranate oleate desaturase were co-expressed in canola-type Brassica napus. Transgenic B. napus lines accumulated up to 11% (w/w) of the total fatty acids as PuA in the seed oil, which is the highest level of PuA reported in metabolically engineered oilseed crops so far. Levels of seed oil PuA were stable over two generations and had no negative effects on seed germination. The transgenic B. napus lines with the highest PuA levels contained multiple transgene insertions and the PuA content of B. napus seed oil was correlated with efficiency of oleic acid desaturation and linoleic acid conjugation. In addition, PuA accumulated at lower levels in polar lipids (5.0-6.9%) than triacylglycerol (7.5-10.6%), and more than 60% of triacylglycerol-associated PuA was present at the sn-2 position. This study provides the basis for the commercial production of PuA in transgenic oilseed crops and thus would open new prospects for the application of this unusual fatty acid in health and industry.

The oxylipin and endocannabidome responses in acute phase Plasmodium falciparum malaria in children

BACKGROUND

Oxylipins and endocannabinoids are low molecular weight bioactive lipids that are crucial for initiation and resolution of inflammation during microbial infections. Metabolic complications in malaria are recognized contributors to severe and fatal malaria, but the impact of malaria infection on the production of small lipid derived signalling molecules is unknown. Knowledge of immunoregulatory patterns of these molecules in malaria is of great value for better understanding of the disease and improvement of treatment regimes, since the action of these classes of molecules is directly connected to the inflammatory response of the organism.

METHODS

Detection of oxylipins and endocannabinoids from plasma samples from forty children with uncomplicated and severe malaria as well as twenty controls was done after solid phase extraction followed by chromatography mass spectrometry analysis. The stable isotope dilution method was used for compound quantification. Data analysis was done with multivariate (principal component analysis (PCA), orthogonal partial least squares discriminant analysis (OPLS-DA®) and univariate approaches (receiver operating characteristic (ROC) curves, t tests, correlation analysis).

RESULTS

Forty different oxylipin and thirteen endocannabinoid metabolites were detected in the studied samples, with one oxylipin (thromboxane B2, TXB2) in significantly lower levels and four endocannabinoids (OEA, PEA, DEA and EPEA) at significantly higher levels in infected individuals as compared to controls according to t test analysis with Bonferroni correction. Three oxylipins (13-HODE, 9-HODE and 13-oxo-ODE) were higher in severe compared to uncomplicated malaria cases according to the results from multivariate analysis. Observed changes in oxylipin levels can be connected to activation of cytochrome P450 (CYP) and 5-lipoxygenase (5-LOX) metabolic pathways in malaria infected individuals compared to controls, and related to increased levels of all linoleic acid oxylipins in severe patients compared to uncomplicated ones. The endocannabinoids were extremely responsive to malaria infection with majority of this class of molecules found at higher levels in infected individuals compared to controls.

CONCLUSIONS

It was possible to detect oxylipin and endocannabinoid molecules that can be potential biomarkers for differentiation between malaria infected individuals and controls and between different classes of malaria. Metabolic pathways that could be targeted towards an adjunctive therapy in the treatment of malaria were also pinpointed.

[Mineral elements analysis of Momordica charantiap seeds by ICP-AES and fatty acid profile identification of seed oil by GC-MS]

In the present study, a special kind of Momordica charantia seeds produced in Hai Nan was selected and analyzed. Firstly, inductively coupled plasma-atomic emission spectrophotometry (ICP-AES) was used to determine the mineral elements. It was clear that the contents of K, Mg and P are the highest in the seeds; Cr and Zn takes up to 5.65% and 45.45% high, especially, which are rare in plant foods. These minerals, especially Cr and Zn might have a complex effect on those proteins or polysaccharides and form a stronger anticipation of hyperlipidemia, hyperglycemia and cholesterol. Secondly, seed oil was extracted by supercritical CO2 extraction with a yield ratio of 36.89, and the fatty acids were treated by methylation in alkaline process and purified by thin-layer chromatography, then analyzed by gas chromatography-mass spectrometer (GC-MS) identification. The saturated fatty acids (SFA) take up 36.712, and mainly are stearic acid; monounsaturated fatty acid (MUFA) is only 3.33% which is dominantly linoleic acid (LA); Polyunsaturated fatty acid (PUFA) accounted for 59.96%, and the alpha-eleostearic acid takes up 54.26% as the main fatty acids in all. The plentiful alpha-eleostearic acid leads to strong effects of inhibiting tumor cell proliferation, lowering blood fat, anti-cancer, anti-inflammatory and preventing cardiovascular diseases, and so on. Knowing clearly the mineral elements distribution and identifying the composition of fatty acid, especially the main fatty acids in the oil, are both of great guiding importance to further exploit the clinical and edible value in Momordica charantiap seeds.

Identification of 4-oxo-2-hexenal and other direct mutagens formed in model lipid peroxidation reactions as dGuo adducts

We searched for mutagens that react with 2'-deoxyguanosine (dGuo) in model systems of lipid peroxidation. To autoxidation systems of methyl linoleate (model of omega-6 fat), methyl alpha-linolenate (MLN) (model of omega-3 fat), and commercial salad oil, dGuo was added. The reaction mixtures were analyzed by HPLC. Six adducts were detected, and their structures were determined by 1H and 13C NMR, UV, and mass spectra and by comparison with synthetic authentic samples. The mutagens that reacted with dGuo to form these adducts were proposed as glyoxal, glyoxylic acid, ethylglyoxal, and 4-oxo-2-hexenal (4-OHE). The formation of 8-hydroxy-dGuo, an oxidized product of dGuo, was also detected in the model reaction mixtures. Among them, glyoxal and glyoxylic acid are known mutagens, while ethylglyoxal and 4-OHE, produced from MLN, have not been reported as mutagens thus far. We confirmed the mutagenic activity of 4-OHE with Salmonella strains, TA100 and TA104, without S9 mix. These compounds may be involved in lipid peroxide-related cancers.

Dietary n-6 and n-3 fatty acid balance and cardiovascular health

Epidemiological and clinical studies have established that the n-6 fatty acid, linoleic acid (LA), and the n-3 fatty acids, linolenic acid (LNA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) collectively protect against coronary heart disease (CHD). LA is the major dietary fatty acid regulating low-density lipoprotein (LDL)-C metabolism by downregulating LDL-C production and enhancing its clearance. Further, the available mass of LA is a critical factor determining the hyperlipemic effects of other dietary fat components, such as saturated and trans fatty acids, as well as cholesterol. By contrast, n-3 fatty acids, especially EPA and DHA, are potent antiarryhthmic agents. EPA and DHA also improve vascular endothelial function and help lower blood pressure, platelet sensitivity, and the serum triglyceride level. The distinct functions of these two families make the balance between dietary n-6 and n-3 fatty acids an important consideration influencing cardiovascular health. Based on published literature describing practical dietary intakes, we suggest that consumption of ~6% en LA, 0.75% en LNA, and 0.25% en EPA + DHA represents adequate and achievable intakes for most healthy adults. This corresponds to an n-6/n-3 ratio of ~6:1. However, the absolute mass of essential fatty acids consumed, rather than their n-6/n-3 ratio, should be the first consideration when contemplating lifelong dietary habits affecting cardiovascular benefit from their intake.

Enhanced production of antimicrobial sesquiterpenes and lipoxygenase metabolites in elicitor-treated hairy root cultures of Solanum tuberosum

Potato (Solanum tuberosum) hairy root cultures, established by infecting potato tuber discs with Agrobacterium rhizogenes, were used as a model system for the production of antimicrobial sesquiterpenes and lipoxygenase (LOX) metabolites. Of the four sesquiterpene phytoalexins (rishitin, lubimin, phytuberin and phytuberol) detected in elicitor-treated hairy root cultures, rishitin (213 micrograms g-1 dry wt) was the most predominant followed by lubimin (171 micrograms g-1 dry wt). The elicitors also induced LOX activity (25-fold increase) and LOX metabolites, mainly 9-hydroxyoctadecadienoic acid and 9-hydroxyoctadecatrienoic acid, in potato hairy root cultures. The combination of fungal elicitor plus cyclodextrin was the most effective elicitor treatment, followed by methyl jasmonate plus cyclodextrin in inducing sesquiterpenes and LOX metabolites.

A gas chromatographic-mass spectrometric method using a PoraPLOT column for the detection of hydroperoxide lyase in Chlorella pyrenoidosa

A gas chromatographic-mass spectrometric (GC-MS) method using a PoraPLOT Q column was developed for the analysis and identification of the volatile products produced by the action of hydroperoxide lyase (HPLS) upon 13-hydroperoxylinoleic or 13-hydroperoxylinolenic acids. The developed procedure required no derivatization, was not affected by the presence of water, did not require cryogenic conditions to be maintained during injection, and allowed for the quantitation of most products. An acetone powder preparation of Chlorella pyrenoidosa cells was triturated with borate buffer pH = 8.0, and the mixture centrifuged at 12,000 x g. The supernatant and pellet were assayed for HPLS activity by GC-MS analysis of the volatile products given by linoleic acid hydroperoxide. The data showed that the majority of HPLS activity resides in the pellet fraction, and that the primary volatile component was pentane, with smaller amounts of 2-(Z)-pentene and 1-pentene being produced. The fact that HPLS activity resides in the water-insoluble fraction of the acetone powder suggests that HPLS from Chlorella is a membrane-associated enzyme. This investigation also determined that a spectrophotometric assay using alcohol dehydrogenase for measuring HPLS activity was not specific, but measured enzymatic activity other than HPLS.

Polyunsaturated fatty acid alkoxyl radicals exist as carbon-centered epoxyallylic radicals: a key step in hydroperoxide-amplified lipid peroxidation

13-Hydroperoxyoctadeca-9,11,15-trienoic acid was reacted with a catalytic amount of 5,10,15,20-tetraphenyl-21H,23H-porphyrin iron(III) chloride in dichloromethane containing 2,4,6-tri-tert-butylphenol. The principal products were identified as 13-oxooctadeca-9,11,15-trienoic acid, 13-oxotrideca-9,11-dienoic acid, and a series of isomeric epoxyaryl ethers [9-(2,4,6-tri-tert-butylphenoxy)-12,13-epoxyoctadec-10-enoic acids and 11-(2,4,6-tri-tert-butylphenoxy)-12,13-epoxyoctadec-9-enoic acids]. The epoxyaryl ethers are coupling products of 2,4,6-tri-tert-butylphenoxyl radical and an epoxyallylic radical formed by cyclization of an intermediate alkoxyl radical. The high yield of epoxyaryl ethers relative to 13-oxotrideca-9,11-dienoic acid suggests the equilibrium between alkoxyl radical and epoxyallylic radical lies predominantly toward epoxyallylic radical. This cyclization appears to be a key step in the amplification of lipid peroxidation by polyunsaturated fatty acid hydroperoxides.

The occurrence of furan fatty acids in Isochrysis sp. and Phaeodactylum tricornutum

Two algae species with a fundamentally different fatty acid composition were investigated for their furan fatty acid (F-acid) content. Isochrysis sp. contains different F-acids with a pentyl side chain in alpha'-position of the furan ring. In consideration of its fatty acid composition which is predominated by compounds with a C-18 chain, this result supports the assumption that pentyl-F-acids derive from linoleic acid. In contrast, only F-acids with propyl side chain were found in Phaeodactylum tricornutum. The low content of C-18 fatty acids in this diatomae contradicts the previous hypothesis that linolenic acid is the precursor of propyl-F-acids. But the presence of (n - 4) unsaturated fatty acids with 16 carbon atoms in Phaeodactylum tricornutum suggests that propyl-F-acids are synthesized from 9,12-hexadecadienoic acid in a very similar biogenetic pathway than pentyl-F-acids.

Serum cholesterol, cholesteryl ester, and high-density lipoprotein development in newborn infants: response to formulas supplemented with cholesterol and gamma-linolenic acid

Healthy newborn infants were either breast-fed or randomly designated to receive a standard formula, formula plus cholesterol, or formula plus gamma-linolenic acid at birth. At 0, 7, and 30 days of life, the following variables were measured: cholesteryl esters (cholesteryl arachidonate, cholesteryl oleate, cholesteryl palmitate, and cholesteryl linoleate), high-density lipoprotein (HDL) cholesterol, apoproteins (A-I, A-II, B, C-II, C-III, and E), and the cholesterol and apoprotein A-I content of the HDL subfractions HDL-2b, HDL-(2a + 3a), and HDL-(3b + 3c). Breast-fed infants had higher serum levels of cholesterol, cholesteryl oleate, cholesteryl palmitate, cholesteryl arachidonate, and HDL-2b than had formula-fed infants. Addition of gamma-linolenic acid to formula raised cholesteryl-arachidonate levels, and cholesterol and gamma-linolenic acid raised serum HDL-2b levels compared with those produced by unsupplemented formula. Our data suggest that both exogenous cholesterol and gamma-linolenic acid contribute to the maturation of HDL particles associated with human milk consumption in newborn infants. They may also promote adequate delivery of cholesterol and arachidonic acid to the developing brain.

Dietary n-3 (omega-3) polyunsaturated fatty acid effects on animal tumorigenesis

Environmental variables influence the incidence and expression of disease. Dietary fat is one environmental variable that has been associated experimentally and epidemiologically with alterations in certain types of tumorigenesis. Recently, detailed biochemical analyses have shown that not all fatty acid families possess the same tumor-promoting potential. In general, diets containing high levels of the n-6 polyunsaturated fatty acids have routinely enhanced tumorigenesis in lipid sensitive carcinogen-induced and tumor transplant tumor models, whereas diets with equivalent levels of n-3 polyunsaturated fatty acids have diminished tumorigenesis. At present, there is no definitive biochemical mechanism that fully explains these observations, but several possibilities have been proposed. One of the most attractive of these hypotheses is that each polyunsaturated fatty acid family has an individual effect on eicosanoid metabolism which determines its tumor-promoting potential. Regardless of current uncertainties about mechanisms of action, however, results of numerous animal models affirm the importance of qualitative, as well as quantitative, dietary lipid differences on tumorigenesis. This knowledge strengthens the probability that further advances in our understanding of lipid-tumor interrelationships will have important preventive and therapeutic medical benefits.

Activation of the neutrophil NADPH-oxidase by free fatty acids requires the ionized carboxyl group and partitioning into membrane lipid

To investigate NADPH-oxidase activation, we studied the effects of free fatty acid (FFA), their uncharged derivatives, and calcium on membrane lipid structure and superoxide anion (O2-) release from intact neutrophils and in cell-free O2(-)-generating systems. This study determined that in calcium-free phosphate-buffered saline (PBS), cis-unsaturated FFA (cis FFA), trans-unsaturated FFA (trans FFA), and to a limited extent saturated FFA decreased the polarization of the membrane lipid structure probe 1,6-diphenyl-1,3,5-hexatriene (DPH), and these decreases correlated with partitioning of the FFA into the plasmalemma and the release of O2- from intact neutrophils and in cell-free preparations. Although a decrease in DPH polarization was always observed under conditions that resulted in the release of O2-, there was not a direct correlation between the amount of decrease in DPH polarization and the release of O2-. Trans FFA did not induce a dose-dependent decrease or as dramatic a decrease in DPH polarization compared with cis FFA, yet the trans FFA stimulated a greater release of O2- at 2.5, 5, and 10 microM concentrations. In addition, responses of the neutrophil to trans FFA, but not cis FFA, were differentially affected by the presence of calcium. When 0.1 mM calcium was added to the PBS decreases in DPH polarization in response to trans FFA were reduced by greater than 60%, whereas O2- was reduced by only 25-36%. The addition of 0.1 mM calcium 3 min after the trans FFA had partitioned into the membrane also reversed by 50-65% decreases in DPH polarization but did not affect the release of O2-. In the presence of 0.9 mM calcium, only the cis FFA decreased DPH polarization or stimulated the release of O2-. Calcium is known to interact more readily with the ionized carboxyl group of trans FFA, neutralizing the anionic charge through an electrostatic interaction. In support of the requirement for the ionized carboxyl group, structurally similar uncharged cis, trans, and saturated fatty alcohols; methyl esters; and aldehydes decreased DPH polarization in the absence and presence of 0.9 mM calcium; however, none of these compounds stimulated the release of O2-. These results indicate that, in addition to the partitioning of FFA into the plasmalemma, which results in calcium-modulatable decreases in DPH polarization, activation or assembly of the NADPH-oxidase requires the ionized carboxyl group.

Vitamin A and glutathione-mediated free radical damage: competing reactions with polyunsaturated fatty acids and vitamin C

Vitamin A (retinol reacts extremely rapidly (k = 1.4 x 10(9) M-1 s-1) with thiyl free radicals derived from glutathione to form a free radical with a very strong visible absorption (lambda max. = 380 nm, E max. = 4.0 x 10(4) M-1 cm-1). Arachidonate, linolenate, linoleate and ascorbate also react readily but much more slowly (k = 2.2 x 10(7), 1.9 x 10(7), 1.3 x 10(7) and 3.6 x 10(8) M-1 s-1 respectively). These results support the possibility that vitamin A might play a role in protecting lipid membranes against thiyl free radical mediated damage.

Thiyl radical attack on polyunsaturated fatty acids: a possible route to lipid peroxidation

Absolute rate constants have been measured for the reaction of cysteinyl free radicals, CysS., with linoleic (18:2), linolenic (18:3) and arachidonic acid (20:4) in water/alcohol mixtures using the radiation chemical technique of pulse radiolysis. They are in the order of 10(6)-10(7) M-1 s-1 and increase with the number of biallylic functions, and with the polarity of the solvent. The reaction is shown to be a hydrogen atom abstraction from biallylic C-H bonds and yields pentadienyl radicals. The thiol mediated repair of the latter is considerably slower. Thiyl free radicals must consequently be considered as a potential source of lipid peroxidation.

Diesel soot particles catalyze the production of oxy-radicals

The formation of a strong oxidant similar to the OH. radical is catalyzed by diesel soot particles in the presence of cysteine and hydrogen peroxide or in the presence of light. The oxidant(s) formed causes fragmentation of methylthioketobutyric acid measurable as ethylene release. Furthermore, the model carotenoid crocin is bleached and thiobarbituric-acid-reactive material (malondialdehyde) is produced from linolenic acid. All reactions are inhibited by scavengers (propyl gallate, alpha-tocopherol, diazobicyclooctane) and by catalase. The reactions observed suggest that the toxicity and mutagenicity of diesel soot particles is at least in part due to the formation of reactive oxygen species.

Interaction of vitamin E and its model compounds with unsaturated fatty acids in homogeneous solution

Either alpha-tocopherol (vitamin E) or one of its model compounds having side chains of different length at the 2-position of alpha-tocopherol, forms complexes with an unsaturated fatty acid in methanol. For complex formation, the isoprenoid side chain and hydroxy group of alpha-tocopherol are unessential and, rather, the methyl groups attached to the aromatic ring of the chromanol moiety seems to be responsible. For better interaction, more than three methylene-interrupted Z double bonds of a fatty acid are necessary. These findings are incompatible with the hypothesis of Diplock and Lucy on the interaction of vitamin E with each polyunsaturated fatty acid.

Effects of bonellin on lipids

A comparative study was conducted on the ability of bonellin, the green pigment of Bonellia viridis, and hematoporphyrin to induce photoperoxidation of lipids in solutions and in erythrocyte ghosts. The inhibiting effect of two free radical scavangers, acetyl-homocysteine-thiolactone and meclofenoxate, indicates that bonellin-induced lipid peroxidation involves free radical production. The relation between bonellin and defence mechanism of Bonellia viridis is discussed.

Red pigment-forming substances from autoxidized linolenate: identification of prostaglandin-like substances

The chemical structures of lipid degradation products capable of reacting with amino acids and forming red pigments were investigated. The red pigment-forming substances (RPS's) derived from autoxidized linolenate in triglyceride of linseed oil were purified successively by gel chromatography on Sephadex LH-20, column chromatography and TLC on Silica gel 60, and HPLC on mu-Porasil. Consequently, three types of RPS's were isolated. IR spectra of RPS's were similar, except for slight differences in the fingerprint region (1300-650 cm-1). These substances included the OH group (3500 cm-1 region), conjugated aldehyde (vC = O 1688 cm-1, vC = C 1635 cm-1) and ketone (vC = O 1740 cm-1) in their molecules. RPS's were analyzed by GLC and GC-MS after derivatization with dimethylhydrazine and/or trimethylsilyl reagents, before and after the reduction with NaBH4 and/or hydrogenation with PtO2. The fragmentation patterns indicated the presence of an ethyl group in addition to the functional groups described above, and the molecular formula was estimated to be C10H14O3. Further elucidation of the structures was obtained by 13C- and 1H-NMR analyses, and evidence was obtained for the presence of a hydroxypentanone ring, a PG-like structure. The sequence of the protons on the ring carbons was unequivocally deduced from the double resonance experiments. All the data taken together suggested that the RPS's were the stereoisomer of 3-(2-ethyl-5-hydroxy-3-oxo) cyclopentanyl-2-propenal.

[Study of radicals formed in the interaction of organic hydroperoxides with ferric ions using the spin trap method]

The mechanism of free radical generation in the reaction of ferrous ion with t-butyl and linolenic acid hydroperoxide was investigated by spin trapping method. The t-butoxyl, methyl, linolenic acid alkoxyl and alkyl radical spin adducts EPR spectra were observed and identified.

Superoxide-dependent lipid peroxidation. Problems with the use of catalase as a specific probe for fenton-derived hydroxyl radicals

Hydroxyl radicals (OH.) can initiate lipid oxidation by hydrogen abstraction. Transition metals however, particularly iron and copper, stimulate lipid oxidation by reacting with lipid peroxides to form new radical species. The haem-iron protein catalase can react non-specifically with lipid peroxides in this way resulting in loss of their conjugated diene structures. When a superoxide-generating system is used to stimulate lipid autoxidation, catalase can conceivably inhibit the reaction in two ways (A) by decomposing lipid peroxides as they are formed (B) through the removal of hydrogen peroxide preventing OH. radical formation. Results presented here suggest that the latter interpretation, although commonly presented, cannot be automatically assumed.

Radiation-induced changes of liposomes and lecithin in non-aqueous media

Radiation-induced changes of lipids in non-aqueous media were studied to elucidate the process of radiation damage in biological membranes. The lipid peroxidation progressed linearly with increasing dose and decreasing dose rate of gamma-irradiation in soyabean lecithin in chloroform. The fatty acid composition of lecithin also changed, especially in linoleic and linolenic acids. Lower dose rate radiation enhanced these changes in oxic condition. Lipid peroxidation was also shown in lipids extracted from irradiated liposomes or in liposomes prepared from irradiated lecithin in chloroform. The dose-dependent glucose efflux was seen in liposomes prepared from irradiated lecithin in chloroform. These results indicate that the peroxidation of lipid molecules might cause radiation damage to the membrane conformation.

The use of gamma-linolenic acid and linoleic acid to differentiate between temporal lobe epilepsy and schizophrenia

Three long-stay, hospitalised schizophrenics who had failed to respond adequately to conventional drug therapy were treated with gamma-linolenic acid and linoleic acid in the form of evening primrose oil. They became substantially worse and electroencephalographic features of temporal lobe epilepsy became apparent. In all three the clinical state dramatically improved when carbamazepine, the conventional therapy for temporal lobe epilepsy was introduced. It can be extremely difficult to distinguish on clinical grounds between schizophrenia and temporal lobe epilepsy, and electroencephalographic studies do not always reveal an abnormality in the temporal lobe syndrome, unless additional procedure such as sphenoidal electroencephalography is undertaken. A trial of therapy with gamma-linolenic acid may prove of considerable value in distinguishing between these two states, so allowing specific therapy to be introduced.

Reduction of ferric heme to ferrous by lipid peroxides: possible relevance to the role of peroxide tone in the regulation of prostaglandin synthesis

In a recent hypothesis, ferrous heme is viewed as interacting with arachidonic acid to convert it to prostaglandin G2. If this hypothesis is correct it must be possible to explain how the ferric heme in hemoglobin which is usually added to the cyclo-oxygenase enzyme to restore activity is reduced. In the present paper we explore the possibility that reduction of the heme is accomplished by lipid peroxides, to see whether such an affect could explain the regulation of cyclo-oxygenase activity by "peroxide tone." Lipid peroxides formed by auto-oxidation or arachidonic acid were found to reduce ferric heme to ferrous heme. The amount of reduction of heme was proportional to the concentration of peroxide. A result of this finding is the expansion of the earlier hypothesis to understand how functional regulation of the cyclo-oxygenase activity may be achieved.

[Prooxidant effect of alpha-tocopherol on essential fatty acids in aqueous media]

Linoleic, linolenic and arachidonic acids, dispersed at a concentration of 2.5 x 10-3 M in an aqueous media pH 7.3, exhibited increasing of their autoxidation rate in presence of 1.5 x 10-5M alpha-tocopherol or more. Cosidering linolenic and arachidonic acids, prooxidant effect increased with alpha-tocopherol level while for linoleic acid this effect was similar with all alpha-tocopherol concentrations. During the prooxidant reaction, alpha-tocopherol was rapidly oxidized. Its oxidation rate depended on hydroperoxides level. It was the most important in presence of arachidonic acid. After 24 hours, alpha-tocopherol was completly oxidized whatever its initial concentration and the type of the fatty acid. Two oxidation products have been identified : alpha-tocopherylquinone for the most part and a dimer of alpha-tocopherol which was detected at the beginning of the reaction.

Further evidence on the structure of slow reacting substance of anaphylaxis (SRS-A)

Arachidonic acid stimulates the release of SRS-A from the peritoneal cavity of sensitized rats or from rat peritoneal cells incubated in vitro. When rat peritoneal cells are incubated in the presence of tritiated arachidonic acid, significant amounts of radioactivity migrate in parallel to bioactivity on purification with Amberlite XAD-8, DE-52, Silicic acid and Sephadex LH-20. Lipoxidase (E.C. 1.13.1.13 and E.C. 1.13.11.12) inactivates mouse, rat and human SRS-A in a concentration-dependent pattern. Following extensive purification, rat SRS-A is also inactivated by the 2 x crystalline suspension of lipoxidase. These findings suggest (a) that SRS-A is a metabolite of arachidonic acid and (b) because of the strict specificity of lipoxidase, that the SRS-A molecule contains a cis, cis-1, 4-pentadiene and a structure very close either to arachidonic acid, to linoleic acid or to linolenic acid.

Prostaglandins, their intermediates and precursors: cardiovascular actions and regulatory roles in normal and abnormal circulatory systems

The characterization of newly found unstable metabolites of arachidonic acid has provided new perspectives for cardiovascular regulatory mechanisms and new insights into disorders of the circulatory system. Since these intermediates are often more potent on and more specific for cardiovascular structures than the classical prostaglandins, they are more likely candidates as physiologic mediators of circulatory events. Their instability in vitro need not preclude these roles; on the contrary, the limited pharmacology described to date suggests that they function purely as local hormones. As such, changes in the rate of generation of these unstable but potent compounds would provide an excellent control system. The stable prostaglandins may represent only overflow of degradation products of the active mediators associated with pathologic events. For example, the dicovery of prostacyclin and the realization that this prostaglandin and not PGE2 is the primary metabolite of arachidonic acid in blood vessels emphasizes the need to reinterpret many of the previously held hypotheses that proposed that prostaglandins of the E series contributed to the regulation of vessel tone and blood pressure, Moreover, the contribution made by abnormal prostaglandin mechanisms to hypertensive disease should now take into account that a deficiency of prostacyclin and not PGE2 could be a major factor causing the elevated tension developed in vascular smooth muscle and the augmented vessel responsiveness to stimuli associated with hypertension.

Positional distribution of fatty acids in the glycerophospholipids of Tetrahymena pyriformis

The positional distributions of the fatty acids in the major glycerophospholipids of Tetrahymena pyriformis W were analyzed. A comparison was made of the acyl distributions in normal and ergosterol-grown cells. It was assumed that the positional arrangement of fatty acids would serve as an indicator of acyltransferase enzyme specificity. The acyltransferases in this protozoan have substrate specificities that direct unsaturated groups, particularly polyunsaturates, to the 2-carbon of the glycerophospholipids. An exception is gamma-linolenic acid, which represents a substantial proportion of the total acids at both carbons. Saturated and iso-acids are esterified primarily at the 1-carbon. The qualitative pattern of the fatty acyl distribution is the same in both normal and ergosterol-grown organisms. Sterol substitution produces quantitative differences in the acyl components at both the 1- and 2-carbons of the glycerophospholipids. These differences include a shortening of the average chain length and a decrease in total unsaturation at both the 1- and 2-positions. In addition, there is a modification at the 2-carbon in the relative amounts of the products of two pathways involved in the biosynthesis of fatty acids. The data are interpreted to indicate that the fatty acid transformations in the glycerophospholipids of organisms that contain ergosterol are not the result of altered acyltransferase specificities.

Effect of substrate composition and concentration on aortic cholesterol ester hydrolase activity

Cholesterol ester hydrolase activity of pig aorta has been examined under optimum experimental conditions for hydrolysis of different cholesterol esters. The enzyme specific activity values were in the numerical order of substrates hydrolyzed: cholesteryl linoleate larger than or equal to linolenate greater than palmitate larger than or equal to stearate greater than oleate. The results are discussed in relation to the arterial accumulation of cholesterol esters.

The inhibition of lipid autoxidation by human caeruloplasmin

1. Purified caeruloplasmin was shown to inhibit lipid autoxidation induced by ascorbic acid or inorganic iron in the following systems: (a) an emulsion of linolenic acid in water; (b) an untreated ox brain homogenate in phosphate buffer; (c) a similar homogenate whose susceptibility to autoxidation had been abolished by dialysis or by heating and then restored by the above pro-oxidants. 2. The optimum conditions for this antioxidant activity were studied. 3. Caeruloplasmin did not inhibit autoxidation by u.v. irradiation in dialysed or preheated homogenates. 4. The apoprotein (without copper) had no antioxidant activity, whereas CuSO4 alone was much less effective as an antioxidant. 5. Iron-free transferrin also had some antioxidant activity.

Cholesterol esters and membrane permeability. A nuclear magnetic resonance (MNR) study

Cholesteryl esters have been incorporated into phospholipid vesicles up to 5 mole percent. Excess ester separates out into a separate phase which resembles the mesomorphic droplets of atherosclerosis. The incorporation of 5 mole percent cholesteryl palmitate is shown by 31P NMR studies to increase the permeability of the model membranes to ions 10-fold. The same incorporation of cholesteryl linoleate does not affect the membrane permeability. Implications of these findings, and the significance of the cholesteryl ester/free cholesterol ratio upon atherosclerosis is discussed.

[Breakdown of linoleic and linolenic acid hydroperoxides in the presence of ascorbic acid analysis of the volatile aldehydes (author's transl)]

Hydroperoxide emulsions with 10(-3) mol ascorbic acid were stored for 19 h at 22 degrees C. Volatile aldehydes were formed in the presence of oxygen and traces of metals. The main compounds were identified as follows (mol-%): 2-pentenal [51] and 2-hexenal [22] from 13-hydroperoxioctadeca-9,11,15-trienoic acid; propanol [38] and 2-hexenal [25] from 9-hydroperoxioctadeca-10,12,15-trienoic acid; hexanal [82] respectively [66] from 13-hydroperoxioctadeca-9,11-respectively 9-hydroperoxioctadeca-10,12-dienoic acid. C9 and C10 aldehydes were only detected in very low concentrations as fragments of the 9-hydroperoxides.