Linked Life Data

8789736

Source:http://linkedlifedata.com/resource/pubmed/id/8789736

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1996-10-23
pubmed:abstractText
High pressure liquid chromatography with electrochemical detection (HPLC-ED) was employed in conjugation with a sensitive and specific salicylate hydroxylation assay to evaluate the immediate effects of hydroxyl radical (.OH) attack on four catechol intermediates of eumelanin, dopamine (3,4-dihydroxyphenylethylamine), its precursor dopa (3,4-dihydroxyphenylalanine), and their respective neurotoxic trihydroxyphenyl derivatives, 6-hydroxydopamine (2,4,5-trihydroxyphenylethylamine,6-OHDA) and 6-hydroxydopa(2,4,5-trihydroxyphenylalanine, TOPA). Semiquinone and quinone species were identified as the initial products of the oxidation of these four catechol substrates. The enhanced oxidations of the catechols when exposed to .OH attack was accompanied by marked decreases in the level of each semiquinone species. Quinone levels were elevated in reactions involving .OH attack on dopamine and 6-OHDA, but absent in reactions involving radical attack on dopa or TOPA, suggesting that dopaquinone (DOQ) and TOPA p-quinone (TOPA p-Q) are oxidized more rapidly by .OH than are the quinones of dopamine and 6-OHDA. The formation of 6-OHDA p-quinone (6-OHDA p-Q) in incubations involving DA and .OH suggest that the .OH-mediated hydroxylation of DA may be a mechanism for generating this potentially cytotoxic trihydroxyphenyl. The results of this study demonstrate for the first time that semiquinone and quinone intermediates of eumelanin are the initial products derived from the .OH-mediated oxidations of dopa, DA, TOPA, and 6-OHDA. These observations suggest that if .OH is generated beyond the capabilities of cytoprotective mechanisms, the radical can rapidly oxidize catechol precursors, augment melanogenesis, and generate additional cytotoxic quinoid intermediates of eumelanin.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0893-5785
pubmed:author
pubmed:issnType
Print
pubmed:volume
8
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
283-93
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
The effects of hydroxyl radical attack on dopa, dopamine, 6-hydroxydopa, and 6-hydroxydopamine.
pubmed:affiliation
Department of Biology, Loyola University of Chicago, IL 60626, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't