Linked Life Data

12049796

Source:http://linkedlifedata.com/resource/pubmed/id/12049796

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2002-6-6
pubmed:abstractText
In the presence of iron or copper ions, the course of the oxidation in air of 5-S-cysteinyldopa (1), the main biosynthetic precursor of pheomelanins and trichochromes, was markedly changed affording two main products. One of these was identified as the oxobenzothiazine 8, previously obtained under nonphysiologically relevant conditions, while the other was characterized as the novel hydroxybenzothiazole 9. Besides 8 and 9, carboxylated and noncarboxylated benzothiazine products were obtained by persulfate oxidation of 1 in the presence of iron or copper ions. The ratio of formation yields of carboxylated/noncarboxylated benzothiazines, determined after reduction of the mixture, was lower than that of the control reaction run in the absence of metal ions, and much lower than that of the oxidation carried out in the presence of zinc ions, in agreement with a recent report. Notably, 8 and 9 were formed in variable yields under different oxidation conditions including tyrosinase/O(2), peroxidase/hydrogen peroxide, and the hydrogen peroxide/or (9E,11Z,13S)-13-hydroperoxyoctadeca-9,11-dienoic acid/Fe(III) systems. Mechanistic routes to 8 and 9 were proposed based on the results of experiments involving in situ generation of labile benzothiazine intermediates. Overall, these results allow to formulate an improved biosynthetic scheme in which metal ions act as critical regulatory factors determining pheomelanin vs. trichochromes formation.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
6
pubmed:volume
1571
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
157-66
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2002
pubmed:articleTitle
Metal ions as potential regulatory factors in the biosynthesis of red hair pigments: a new benzothiazole intermediate in the iron or copper assisted oxidation of 5-S-cysteinyldopa.
pubmed:affiliation
Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Complesso Universitario Monte S. Angelo, Via Cinthia 4, Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't