Rafael Codony

Biological effects of oxysterols: Current status

A review of relevant literature on biological activities of oxysterols (OS) and cholesterol is presented. The data clearly demonstrate manifold biological activities, often detrimental, for OS compared with little or no such activity of a deleterious nature for cholesterol itself. Cholesterol is perhaps the single most important compound in animal tissue and, as such, it is difficult to imagine it as a toxin or hazard. In contrast, OS exhibit cytotoxicity to a wide variety of cells leading to angiotoxic and atherogenic effects; alter vascular permeability to albumin; alter prostaglandin synthesis and stimulate platelet aggregation, an important process facilitating atherosclerosis and thrombosis; alter the functionality of low density lipoprotein (LDL) receptors, possibly stimulating hypercholesterolaemia; modify cholesteryl ester accumulation in various cells, inducing foam cell formation; and enrich the LDL particle in cholesteryl esters, possibly increasing its atherogenicity. Furthermore, OS are mutagenic and carcinogenic, although some have been studied as antitumour agents based on their cytotoxic properties. Moreover, numerous studies have implicated OS in membrane and enzyme alterations that are interrelated with many of the foregoing effects. The authors find that OS deserve much more attention than cholesterol itself in terms of research activity but that unfortunately the reverse is true with regard to funding.

Determination of hydroperoxides in foods and biological samples by the ferrous oxidation-xylenol orange method: a review of the factors that influence the method's performance.

The oxidation of lipids yields both primary and secondary oxidation compounds that produce undesirable biological effects [1– 3] and includes loss of nutritional value and sensory problems in foods [4,5]. Primary oxidation products include lipid hydroperoxides (HP) which can further decompose into secondary oxidation products and/or react with other compounds present in the food or biological material [6–8]. The measurement of HP, in connection with free radicals and other reactive oxygen species, has been used as indication of oxidative stress in biological samples [7,9–13] and associated with the pathogenesis of several diseases such as atherosclerosis [14,15], cancer [16,17], and neurodegenerative diseases [18–20]. Unfortunately, the majority of analyses to assess lipid oxidation in biological and food samples determine only secondary oxidation products, whereas the determination of HP could give an early and more accurate indication of the oxidative status. Hence, a proper assessment of the degree of oxidation in any kind of sample should be accomplished by the appropriate selection of the methods that include the determination of both primary oxidation products and their decomposition products [8,21,22]. However, the determination of lipid HP is quite challenging because many different kinds of HP are produced from lipid oxidation and HP are reactive compounds that rapidly react and decompose

Cholesterol and phytosterol oxidation products : analysis, occurrence, and biological effects

Cholesterol Oxidation Products 1. Cholesterol Oxidation Mechanisms 2. Extraction and Purification of Cholesterol Oxidation Products 3. Determination of Cholesterol Oxidation Products by Gas Chromatography 4. Determination of Cholesterol Oxidation Products by High-Performance Liquid Chromatography 5. Determination of Cholesterol Oxidation Products by Thin-Layer Chromatography 6. Harmonization of Cholesterol Oxidation Product Analysis 7. Formation and Content of Cholesterol Oxidation Products in Egg and Egg Products 8. Formation and Content of Cholesterol Oxidation Products in Milk and Dairy Products 9. Formation and Content of Cholesterol Oxidation Products in Meat and Meat Products 10. Formation and Content of Cholesterol Oxidation Products in Seafood and Seafood Products 11. Formation and Content of Cholesterol Oxidation Products in Other Foods 12. Origin and Content of Cholesterol Oxidation Products in Biological Samples 13. Cholesterol Oxidation Products and Atherosclerosis 14. Cholesterol Oxidation Products: Other Biological Effects Phytosterol Oxidation Products 15. Formation and Content of Phytosterol Oxidation Products in Foods 16. Determination of Phytosterol Oxidation Products in Foods and Biological Samples 17. Biological Effects of Phytosterol Oxidation Products, Future Research Areas and Concluding Remarks

Cholesterol oxidation in frozen dark chicken meat: influence of dietary fat source, and α-tocopherol and ascorbic acid supplementation.

A factorial design assessed the effect of dietary fat source (beef tallow, fresh and oxidized sunflower oils, and linseed oil), and α-tocopheryl acetate (α-TA) and ascorbic acid (AA) supplementation (225 and 110 mg/kg feed, respectively) on the cholesterol oxidation product (COP) content and 2-thiobarbituric acid (TBA) values in raw and cooked dark chicken meat vacuum packaged and stored at -20°C for 7 months. COP determination showed good linearity, recovery and precision. Dietary α-TA was highly effective in protecting raw or cooked meat from cholesterol and fatty acid oxidation, regardless of its degree of unsaturation. In contrast, AA supplementation was ineffective and even promoted oxidation in raw meat from broilers fed unsaturated fat diets that had not been supplemented with α-TA. Oxidation values (raw or cooked meat) from α-TA or α-TA+AA supplemented diets were not statistically different (P>0.05). TBA and COP values were significantly correlated in raw samples (r=0.6466, P=0.0001).

Fatty acid, tocopherol and sterol content of some hazelnut varieties (Corylus avellana L.) harvested in Oregon (USA)

Abstract We analysed the fatty acid, tocopherol and sterol composition of several hazelnut varieties of different geographical origins harvested in Oregon. Monounsaturated and polyunsaturated fatty acids were the most predominant fatty acids in hazelnut oil extracted from samples. A one-way analysis of variance revealed significant differences for fatty acid content between varieties. Discriminant analysis using individual fatty acids as variables revealed that hazelnut samples were grouped according to their origin. α-Tocopherol, campesterol, stigmasterol, β-sitosterol and Δ 5 -avenasterol were predominant in the unsaponifiable lipid fraction of hazelnut samples. A Kruskall Wallis nonparametric test revealed significant differences between hazelnut varieties for α-tocopherol and sterol content. However, no significant differences were found in relation to geographical origin.

Dietary Strategies to Improve Nutritional Value, Oxidative Stability, and Sensory Properties of Poultry Products

Consumers demand both safer and more nutritious food products exempt of non-natural origin preservatives or other food additives. In this frame, products with lower fat content and/or a higher ratio in unsaturated fatty acids, especially n-3 fatty acids, are desired because these lipids can help prevent the development of cardiovascular and inflammatory pathologies. The intake of meat products is of interest because they are an excellent source of vitamins and minerals. In addition, the shelf-life of meat products can be extended by the presence of natural antioxidants coming from different sources such as plant extracts. Therefore, different strategies have been studied to improve the nutritional value, oxidative stability, and sensory characteristics of meat products and eggs through different mineral and natural dietary supplements. In comparison to other strategies, dietary supplements present the advantage that first the living animals may efficiently distribute the compounds throughout the tissues and second, the dietary supplementation is safer because the resulting enriched meat products and eggs ensure tolerable amounts in humans. Poultry meats and eggs are widely consumed and their fatty acid profile and tocopherol content can be easily modified through different dietary strategies thus being excellent models to improve their nutritional value and oxidative stability.

Comparison of three methods for the determination of oxysterols in spray-dried egg

Three methods for the GC determination of oxysterols (OSs) in spray-dried egg, which combine different steps of purification, are compared. In addition, the efficiency of silica cartridges in the purification of OSs using four different systems of elution with increasing polarities is studied. The absence of cholesterol oxidation during the application of the analytical procedures is checked, and the linearity of the response and the chromatographic limits of detection and quantification are established. The methods are characterized by the calculation of precision and recovery for the different OSs. The method based on saponification alone is rejected, since it shows much lower precision. The method that includes saponification and silica cartridge purification offers higher reliability than the method based on cartridge purification alone, because it shows a higher precision and larger samples can be processed, which improves the limits of detection and quantification.

Influence of variety and geographical origin on the lipid fraction of hazelnuts (Corylus avellana L.) from Spain: (III) oil stability, tocopherol content and some mineral contents (Mn, Fe, Cu)

Abstract Induction time, acid value and α-tocopherol content of hazelnut oil and some mineral contents (manganese, iron and copper) of hazelnut kernels cultivated in Catalonia (Spain) are determined. Analysis of variance (ANOVA) showed that statistically significant differences existed for: α-tocopherol content, acid value and copper content in relation to the harvesting year of samples. Significant differences were also found for: induction time, manganese and copper contents in relation to the location of samples. On the other hand, no significant differences were found between varieties. In addition, a correlation study was performed between all parameters included in this work. A strong negative correlation was observed between linoleic acid and manganese content, and also copper content and oil stability (Rancimat).

Trans fatty acid content of human milk in Spain

The C18 fatty acid fraction of 38 samples of mature human milk from Spanish women was analyzed using capillary gas chromatography. The average content of trans fatty acids found in these samples represented 0.95% of total fatty acids. This value is lower than the percentage found in human milk from other developed countries in which the consumption of hydrogenated fat is higher. Trans fatty acid content in human milk has been related to the types of fats and oils present in the diets of the nursing mothers. According to the results obtained in this survey, we can also conclude that the amount of trans forms in breast milk lipids is lower than the trans content found in infant formulas in Spain.

Influence of Different Dietary Doses of n-3-or n-6-Rich Vegetable Fats and α-Tocopheryl Acetate Supplementation on Raw and Cooked Rabbit Meat Composition and Oxidative Stability

This study evaluates the effects of replacing beef tallow added to rabbit feeds (3% w/w) by different doses (0%, 1.5% and 3% w/w) of n-6- or n-3-rich vegetable fat sources (sunflower and linseed oil, respectively) and alpha-tocopheryl acetate supplementation (0 and 100 mg/kg) on the fatty acid composition, alpha-tocopherol content, and oxidation levels [assessed by analyzing thiobarbituric acid (TBA) and lipid hydroperoxide values] in rabbit meat. We also measured these parameters after cooking and refrigerated storage of cooked rabbit meat. Both dietary alpha-tocopheryl acetate supplementation and the dose and source of fat added to feeds influenced meat fatty acid composition, modifying the n-6/n-3 ratio, which was more nutritionally favorable when linseed oil was used. Furthermore, the addition of linseed oil and the supplementation with alpha-tocopheryl acetate enhanced long-chain PUFA biosynthesis. However, the addition of 3% linseed oil increased meat oxidation, and although it was reduced by dietary supplementation with alpha-tocopheryl acetate in raw meat, this reduction was not as effective after cooking. Therefore, dietary supplementation with 1.5% linseed oil plus 1.5% beef tallow and with alpha-tocopheryl acetate would be recommended to improve the nutritional quality of rabbit meat.