Linked Life Data

12662346

Source:http://linkedlifedata.com/resource/pubmed/id/12662346

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2003-3-28
pubmed:abstractText
Melatonin and classic antioxidants possess the capacity to scavenge ABTSb+ with IC50s of 4, 11, 15.5, 15.5, 17 and 21 microm for melatonin, glutathione, vitamin C, trolox, NADH and NADPH, respectively. In terms of scavenging ABTSb+, melatonin exhibits a different profile than that of the classic antioxidants. Classic antioxidants scavenge one or less ABTSb+, while each melatonin molecule can scavenge more than one ABTSb+, probably with a maximum of four. Classic antioxidants do not synergize when combined in terms of scavenging ABTSb+. However, a synergistic action is observed when melatonin is combined with any of the classic antioxidants. Cyclic voltammetry indicates that melatonin donates an electron at the potential of 715 mV. The scavenging mechanism of melatonin on ABTSb+ may involve multiple-electron donations via intermediates through a stepwise process. Intermediates including the melatoninyl cation radical, the melatoninyl neutral radical and cyclic 3-hydroxymelatonin (cyclic 3-OHM) and N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) seem to participate in these reactions. More interestingly, the pH of the solution dramatically modifies the ABTSb+ scavenging capacity of melatonin while pH changes have no measurable influence on the scavenging activity of classic antioxidants. An acidic pH markedly reduces the ABTSb+ scavenging capacity of melatonin while an increased pH promotes the interaction of melatonin and ABTSb+. The major melatonin metabolites that develop when melatonin interacts with ABTSb+ are cyclic 3-OHM and AFMK. Cyclic 3-OHM is the intermediate between melatonin and AFMK, and cyclic 3-OHM also has the ability to scavenge ABTSb+. Melatonin and the metabolites which are generated via the interaction of melatonin with ABTSb+, i.e. the melatoninyl cation radical, melatoninyl neutral radical and cyclic 3-OHM, all scavenge ABTSb+. This unique cascade action of melatonin, in terms of scavenging, increases its efficiency to neutralized ABTSb+; this contrasts with the effects of the classic antioxidants.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/1-acetyl-1,2,3,3a,8,8a-hexahydro-8a-..., http://linkedlifedata.com/resource/pubmed/chemical/2,2'-azino-di-(3-ethylbenzothiazolin..., http://linkedlifedata.com/resource/pubmed/chemical/6-hydroxy-2,5,7,8-tetramethylchroman..., http://linkedlifedata.com/resource/pubmed/chemical/Antioxidants, http://linkedlifedata.com/resource/pubmed/chemical/Ascorbic Acid, http://linkedlifedata.com/resource/pubmed/chemical/Benzothiazoles, http://linkedlifedata.com/resource/pubmed/chemical/Cations, http://linkedlifedata.com/resource/pubmed/chemical/Chromans, http://linkedlifedata.com/resource/pubmed/chemical/Free Radical Scavengers, http://linkedlifedata.com/resource/pubmed/chemical/Free Radicals, http://linkedlifedata.com/resource/pubmed/chemical/Glutathione, http://linkedlifedata.com/resource/pubmed/chemical/Kynuramine, http://linkedlifedata.com/resource/pubmed/chemical/Melatonin, http://linkedlifedata.com/resource/pubmed/chemical/N-acetyl-N-formyl-5-methoxykynurenam..., http://linkedlifedata.com/resource/pubmed/chemical/NAD, http://linkedlifedata.com/resource/pubmed/chemical/NADP, http://linkedlifedata.com/resource/pubmed/chemical/Sulfonic Acids
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0742-3098
pubmed:author
pubmed:issnType
Print
pubmed:volume
34
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
249-59
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
Mechanistic and comparative studies of melatonin and classic antioxidants in terms of their interactions with the ABTS cation radical.
pubmed:affiliation
Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't