Linked Life Data

10478924

Source:http://linkedlifedata.com/resource/pubmed/id/10478924

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
1999-11-4
pubmed:abstractText
The proportion of geometrical hydroperoxide isomers generated by aerobic oxidation of methyl linoleate (18:2 Me) in either aqueous emulsion consisting of Tris-HCl buffer (pH 7.4) or in a homogeneous dichloromethane solution was determined to understand the mechanism of lipid oxidation in different reaction systems. Four geometrical isomers were generated after oxidation of 18:2 Me in dichloromethane: methyl 13-hydroperoxy-cis-9, trans-11-octadecadienoate, methyl 13-hydroperoxy-trans-9,trans-11-octadecadienoate, methyl 9-hydroperoxy-trans-10,cis-12-octadecadienoate, and methyl 9-hydroperoxy-trans-10, trans-12-octadecadienoate in the ratios of 1:4:1:4, respectively. The ratios between each isomer did not change until the peroxide value (PV) increased to 58 meq/kg. Oxidation of 18:2 Me in aqueous emulsion yielded the same geometrical isomers of hydroperoxide. However, the ratios were different: 3:2:3:2 until the PV increased to 110 meq/kg. Predominant (60%) formation of trans,trans hydroperoxide isomers was obtained in the oxidation of a mixture of 18:2 Me and methyl laurate (12:0 Me). These results are interpreted to reflect the importance of the concentration of hydrogen atom-donating equivalents to the kinetic preference for different products. The high effective concentration of hydrogen donors in the oxidation of 18:2 Me in emulsions favored the formation of the less stable cis,trans isomers. The lower concentration of hydrogen donor in the dichloromethane solution effectively slowed hydrogen donation and led to the strong preference for the more stable trans,trans isomers. This interpretation was further tested by preparing emulsions of 18:2 Me and 12:0 Me to dilute concentration of hydrogen-donating species using the nonhydrogen-donating 12:0 Me. Consistent with the proposed hypothesis, the proportion of trans,trans isomers increased as a result of 12:0 Me addition.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0024-4201
pubmed:author
pubmed:issnType
Print
pubmed:volume
34
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
675-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Proportion of geometrical hydroperoxide isomers generated by radical oxidation of methyl linoleate in homogeneous solution and in aqueous emulsion.
pubmed:affiliation
Department of Food Science and Technology, Tokyo University of Fisheries, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't