Linked Life Data

15223070

Source:http://linkedlifedata.com/resource/pubmed/id/15223070

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2004-6-29
pubmed:abstractText
Mn(III) ortho-tetrakis(N-ethylpyridinium-2-yl)porphyrin (Mn(III)TE-2-PyP(5+)) effectively scavenges reactive oxygen and nitrogen species in vitro, and protects in vivo, in different rodent models of oxidative stress injuries. Further, Mn(III)TE-2-PyP(5+) was shown to be readily reduced by cellular reductants such as ascorbic acid and glutathione. We now show that tetrahydrobiopterin (BH(4)) is also able to reduce the metal center. Under anaerobic conditions, in phosphate-buffered saline (pH 7.4) at 25 +/- 0.1 degrees C, reduction of Mn(III)TE-2-PyP(5+) occurs through two reaction steps with rate constants k(1) = 1.0 x 10(4) M(-1) s(-1) and k(2) = 1.5 x 10(3) M(-1) s(-1). We ascribe these steps to the formation of tetrahydrobiopterin radical (BH(4)(.+)) (k(1)) that then undergoes oxidation to 6,7-dihydro-8H-biopterin (k(2)), which upon rearrangement gives rise to 7,8-dihydrobiopterin (7,8-BH(2)). Under aerobic conditions, Mn(III)TE-2-PyP(5+) catalytically oxidizes BH(4). This is also true for its longer chain alkyl analog, Mn(III) ortho-tetrakis(N-n-octylpyridinium-2-yl)porphyrin. The reduced Mn(II) porphyrin cannot be oxidized by 7,8-BH(2) or by l-sepiapterin. The data are discussed with regard to the possible impact of the interaction of Mn(III)TE-2-PyP(5+) with BH(4) on endothelial cell proliferation and hence on tumor antiangiogenesis via inhibition of nitric oxide synthase.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0891-5849
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
37
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
367-74
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
Tetrahydrobiopterin rapidly reduces the SOD mimic Mn(III) ortho-tetrakis(N-ethylpyridinium-2-yl)porphyrin.
pubmed:affiliation
Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA. ibatinic@duke.edu
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't