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Ann-therese Karlberg - One of the best experts on this subject based on the ideXlab platform.
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contact allergens formed on air exposure of linalool identification and quantification of Primary and secondary Oxidation products and the effect on skin sensitization
Chemical Research in Toxicology, 2004Co-Authors: Maria Skold, Anna Borje, Elma Harambasic, Ann-therese KarlbergAbstract:Linalool (3,7-dimethyl-1,6-octadien-3-ol) is an important fragrance chemical, frequently used in scented products because of its fresh, flowery odor. Linalool is an unsaturated hydrocarbon and is therefore susceptible to Oxidation in the presence of air. The Primary Oxidation products, that is, hydroperoxides, formed in the autOxidation process, are reactive compounds that can be suspected to act as sensitizers. In the present investigation, we studied the autOxidation of linalool with emphasis on the formation of hydroperoxides. The Oxidation products were isolated using flash chromatography and preparative HPLC and were identified with NMR and GC/MS, using synthesized reference compounds. Two hydroperoxides and several different secondary Oxidation products were identified, among which some contain structural features that make them potential allergens. The amounts of linalool and the major Oxidation products were quantified over time, using GC and an HPLC-method, suitable for the analysis of thermolabi...
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Structure elucidation, synthesis, and contact allergenic activity of a major hydroperoxide formed at autOxidation of the ethoxylated surfactant C12E5.
Chemical Research in Toxicology, 2003Co-Authors: Anna Bodin, Malin Linnerborg, J. Lars G. Nilsson, Ann-therese KarlbergAbstract:Ethoxylated alcohols, widely used as surfactants, are known to be susceptible to Oxidation when exposed to air. At autOxidation, a complex mixture is formed, in which alkyl poly(ethylene glycol) aldehydes, alkyl poly(ethylene glycol) formates, hydroxyaldehydes, and formaldehyde have previously been identified. These compounds are all secondary Oxidation products, some of which have been shown to be skin sensitizers and irritants. The Primary Oxidation products from ethoxylated alcohols are described in the literature as peroxides and hydroperoxides, but their structures have not been elucidated more closely. Peroxides and hydroperoxides are usually reactive species and can be suspected to be biologically active as skin sensitizers and irritants. In the present investigation, we studied the autOxidation of the pure ethoxylated alcohol pentaethylene glycol mono-n-dodecyl ether (C12E5), using NMR and HPLC-MS. On the basis of experience from previous studies on a small model compound, diethyleneglycol monoeth...
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Primary Oxidation products affect the quantification of formaldehyde in autoxidized fatty alcohol ethoxylates when using dnph derivatization
Contact Dermatitis, 2003Co-Authors: Jan Sollenberg, Anna Bodin, Malin Linnerborg, Ann-therese KarlbergAbstract:Non-ionic surfactants, e.g. fatty alcohol ethoxylates, are considered to cause less skin irritation than other types of surfactants. However, the autOxidation of alcohol ethoxylates generates products that are both skin irritating and sensitizing, such as formaldehyde. It has been suggested that formaldehyde be used as an indicator of the degree of autOxidation of fatty alcohol ethoxylates, and thus also as an indicator of the sensitizing capacity of the product. Attempts to analyse formaldehyde in autoxidized ethoxylates using 2,4-dinitrophenylhydrazine derivatization resulted in formation of the corresponding hydrazone not only from free formaldehyde but also from autOxidation products during the derivatization reaction. Consequently, this derivatizing agent is inappropriate for the determination of formaldehyde in autoxidized fatty alcohol ethoxylates. Focus on the content of Primary Oxidation products, i.e. hydroperoxides/peroxides, is suggested, particularly as they also are potent sensitizers.
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Novel hydroperoxides as Primary autOxidation products of a model ethoxylated surfactant
Journal of Surfactants and Detergents, 2002Co-Authors: Anna Bodin, Malin Linnerborg, J. Lars G. Nilsson, Ann-therese KarlbergAbstract:Ethoxylated alcohols, widely used as surfactants, are susceptible to Oxidation when exposed to air. A complex mixture is formed, in which alkylated aldehydes, alkylated formates, hydroxyaldehydes, and formaldehyde have previously been identified by our group. The compounds identified so fat are all secondary Oxidation products, some of which have been shown to be skin sensitizers and irritants. The Primary Oxidation products from ethoxylated surfactants have been described as peroxides and hydroperoxides, but their structures have not been elucidated more closely. Hydroperoxides are reactive species and can be suspected to be biologically active as skin sensitizers and irritants. In the present study we used a small model compound, diethylenglycol monoethylether (C_2E_2), to facilitate the identification of Primary Oxidation products formed at autOxidation of ethoxylated surfactants. By performing NMR and HPLC-MS analyses, we found that at least four different hydroperoxides were formed at autOxidation of C_2E_2, one of them dominating in concentration over the others. The hydroperoxide present in the highest concentration was identified as 2-[2-(1-hydroperoxyethoxy)ethoxy]ethanol.
Sidsel Jensen - One of the best experts on this subject based on the ideXlab platform.
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antioxidants and shelf life of whole wheat bread
Journal of Cereal Science, 2011Co-Authors: Henrik Ostdal, Leif H Skibsted, Sidsel Jensen, Anette Kistrup ThyboAbstract:Abstract Industrially produced bread normally operates with a shelf life of several weeks at room temperature and indications of storage-related off-flavour development as a consequence of lipid Oxidation have been suggested. The present study has tested enrichment of whole wheat bread with α-tocopherol or commercially used rosemary extracts for production of bread loaves with higher oxidative stability and hence better overall sensory quality. Bread quality was evaluated by sensory profiling, determination of antioxidative capacity, determination of lipid hydroperoxides as Primary Oxidation products, and analysis of volatile compounds including secondary lipid Oxidation products. Enrichment of bread with α-tocopherol resulted in higher degrees of rancid aroma and flavour in fresh samples, which was explained by higher levels of secondary Oxidation products, whereas enrichment of bread with rosemary extracts did not have any effect. Accordingly, application of antioxidants cannot, based on the current data, be recommended for achievement of bread with improved sensory properties during storage.
Sami Sayadi - One of the best experts on this subject based on the ideXlab platform.
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oxidative stability of refined olive and sunflower oils supplemented with lycopene rich oleoresin from tomato peels industrial by product during accelerated shelf life storage
Food Chemistry, 2018Co-Authors: Mouna Kehili, Sirine Choura, Ayachi Zammel, Noureddine Allouche, Sami SayadiAbstract:Abstract Tomato peels by-product from a Tunisian industry was used for the extraction of lycopene-rich oleoresin using hexane solvent maceration. Tomato peels oleoresin, TPO, exhibited competitive free radicals scavenging activity with synthetic antioxidants. The efficacy of TPO in stabilizing refined olive (ROO) and sunflower (RSO) oils was investigated for five months, under accelerated shelf-life, compared to the synthetic antioxidant, butylated hydroxytoluene (BHT). TPO was added to ROO and RSO at four different concentrations, namely 250, 500, 1000 and 2000 µg/g and BHT standard at 200 µg/g. Lipid Oxidation was tracked by measuring the peroxide value, acidity, conjugated dienes and trienes. Results suggested the highest efficiency of 250 µg/g and 2000 µg/g of TPO, referring to 5 µg/g and 40 µg/g of lycopene, for the oxidative stabilization of ROO and RSO, respectively. The protective effect of TPO against the Primary Oxidation of these refined oils was significantly correlated to their lycopene contents.
Kozi Asada - One of the best experts on this subject based on the ideXlab platform.
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thylakoid bound ascorbate peroxidase in spinach chloroplasts and photoreduction of its Primary Oxidation product monodehydroascorbate radicals in thylakoids
Plant and Cell Physiology, 1992Co-Authors: Chikahiro Miyake, Kozi AsadaAbstract:Ascorbate peroxidase, a key enzyme for the scavenging of hydrogen peroxide in chloroplasts, was found in a thylakoid-bound form in spinach chloroplasts at comparable activity to that in the stroma. The activity of peroxidase was detectable in the thylakoids only when prepared by an ascorbate-containing medium, and enriched in the stroma thylakoids. The thylakoid enzyme was not released from the membranes by either 2 mM EDTA, 1 M KC1, 2 M NaBr or 2 M NaSCN, but was solubilized by detergents. Enzymatic properties of the thylakoid-bound ascorbate peroxidase were very similar to those of the stromal ascorbate peroxidase. Thylakoid-bound ascorbate peroxidase could scavenge the hydrogen peroxide either added or photoproduced by the thylakoids. No photoreductio n of hydrogen peroxide was observed, however, in the thylakoids whose ascorbate peroxidase was inhibited by KCN and thiol reagents or inactivated by the treatment with ascorbate-depletion. The Primary Oxidation product of ascorbate in a reaction of ascorbate peroxidase, monodehydroascorbate (MDA) radical, was photoreduced in the thylakoids, as detected by the quenching of chlorophyll fluorescence, disappearance of EPR signals of the MDA radicals and the MDA radical-induced oxygen evolution. Thus, ascorbate is photoregenerated in the thylakoids from the MDA radicals produced in a reaction of ascorbate peroxidase for the scavenging of hydrogen peroxide.
Anette Kistrup Thybo - One of the best experts on this subject based on the ideXlab platform.
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antioxidants and shelf life of whole wheat bread
Journal of Cereal Science, 2011Co-Authors: Henrik Ostdal, Leif H Skibsted, Sidsel Jensen, Anette Kistrup ThyboAbstract:Abstract Industrially produced bread normally operates with a shelf life of several weeks at room temperature and indications of storage-related off-flavour development as a consequence of lipid Oxidation have been suggested. The present study has tested enrichment of whole wheat bread with α-tocopherol or commercially used rosemary extracts for production of bread loaves with higher oxidative stability and hence better overall sensory quality. Bread quality was evaluated by sensory profiling, determination of antioxidative capacity, determination of lipid hydroperoxides as Primary Oxidation products, and analysis of volatile compounds including secondary lipid Oxidation products. Enrichment of bread with α-tocopherol resulted in higher degrees of rancid aroma and flavour in fresh samples, which was explained by higher levels of secondary Oxidation products, whereas enrichment of bread with rosemary extracts did not have any effect. Accordingly, application of antioxidants cannot, based on the current data, be recommended for achievement of bread with improved sensory properties during storage.