Linked Life Data

9119263

Source:http://linkedlifedata.com/resource/pubmed/id/9119263

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
1997-4-22
pubmed:abstractText
Scavenging of singlet oxygen (1O2) by alpha-tocopherol (alpha-Toc) was investigated in liposomes. 1O2 was generated by photoirradiation in the presence of two photosensitizers, water-soluble methylene blue (MB) and lipid-soluble 12-(1-pyrene)dodecanoic acid (PDA). The rates of oxidation of alpha-Toc differed depending on the photosensitizing dye and the membrane charge: in the MB-system, alpha-Toc was oxidized fast in negatively charged dimyristoylphosphatidylcholine (DMPC) liposomes containing dicetylphosphate (DCP) and slowly in neutrally charged DMPC liposomes and positively charged DMPC liposomes containing stearylamine (SA), but in the PDA-system, the oxidation rate was independent of the membrane charge. The charge-dependent difference in the MB-system would be due to the site of 1O2 generation depending on the charge-dependent distribution of MB, because positively charged MB increased the zeta-potential of DCP-DMPC liposomes by its interaction with DCP at the membrane surface, but changed the zeta-potentials of DMPC and SA-DMPC liposomes less because of its location in the bulk water phase. The oxidation rate of alpha-Toc in liposomes was different from that in EtOH solution: in the MB system, the oxidation rate was faster in EtOH solution than in DMPC or SA-DMPC liposomes but the same as that in DCP-DMPC liposomes. However, in the PDA system, the oxidation rate was slower in EtOH solution than in DMPC liposomes with or without a charge. Membrane fluidity changed the rate of alpha-Toc oxidation in liposomes, the rate being higher in the liquid crystalline phase than the gel phase, as judged by the higher rate in DMPC liposomes than in dipalmitoylphosphatidylcholine (DPPC) liposomes at 30 degrees C. The rate constants of alpha-Toc for scavenging, the chemical reaction and physical quenching of 1O2 were determined in membranes using DCP-DMPC liposomes labeled with 1,3-diphenyl-isobenzofuran (DPBF), which traps 1O2. These constants differed in the two photosensitizing systems, being higher in the MB-system than in the PDA-system, and were lower than those in EtOH solution.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/12-(1-pyrene)dodecanoic acid, http://linkedlifedata.com/resource/pubmed/chemical/Ethanol, http://linkedlifedata.com/resource/pubmed/chemical/Free Radical Scavengers, http://linkedlifedata.com/resource/pubmed/chemical/Free Radicals, http://linkedlifedata.com/resource/pubmed/chemical/Lauric Acids, http://linkedlifedata.com/resource/pubmed/chemical/Liposomes, http://linkedlifedata.com/resource/pubmed/chemical/Methylene Blue, http://linkedlifedata.com/resource/pubmed/chemical/Oxygen, http://linkedlifedata.com/resource/pubmed/chemical/Phosphatidylcholines, http://linkedlifedata.com/resource/pubmed/chemical/Photosensitizing Agents, http://linkedlifedata.com/resource/pubmed/chemical/Singlet Oxygen, http://linkedlifedata.com/resource/pubmed/chemical/Solutions, http://linkedlifedata.com/resource/pubmed/chemical/Vitamin E
pubmed:status
MEDLINE
pubmed:issn
0891-5849
pubmed:author
pubmed:issnType
Print
pubmed:volume
22
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
923-30
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Kinetics and dynamics of singlet oxygen scavenging by alpha-tocopherol in phospholipid model membranes.
pubmed:affiliation
Faculty of Pharmaceutical Sciences, Tokushima University, Japan.
pubmed:publicationType
Journal Article, In Vitro