Linked Life Data

16131524

Source:http://linkedlifedata.com/resource/pubmed/id/16131524

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
2005-11-24
pubmed:abstractText
Furamidine is an effective antimicrobial agent; however, oral potency of furamidine is poor. A prodrug of furamidine, 2,5-bis(4-amidinophenyl)furan-bis-O-methylamidoxime (DB289), has greatly improved oral potency. DB289 is transformed to furamidine via O-demethylation, and N-dehydroxylation reactions with four intermediate metabolites formed. The O-demethylation reactions have been shown to be catalyzed by cytochrome P450. The enzymes catalyzing the reductive N-dehydroxylation reactions have not been determined. The objective of this study was to identify the enzymes that catalyze N-dehydroxylation of metabolites M1, a monoamidoxime, and M2, a diamidoxime, formed during generation of furamidine. M1 and M2 metabolism was investigated using human liver microsomes and human soluble cytochrome b5 and NAD cytochrome b5 reductase, expressed in Escherichia coli. Kinetics of M1 and M2 reduction by human liver microsomes exhibited high affinity and moderate capacity. Metabolism was significantly inhibited by antibodies to cytochrome b5 and b5 reductase and by chemical inhibitors of b5 reductase. The amidoximes were efficiently metabolized by liver mitochondria, which contain cytochrome b5/b5 reductase, but not by liver cytosol, which contains minimal amounts of these proteins. Expressed cytochrome b5/b5 reductase, in the absence of any other proteins, efficiently catalyzed reduction of both amidoximes. K(m) values were similar to those for microsomes, and V(max) values were 33- to 36-fold higher in the recombinant system compared with microsomes. Minimal activity was seen with cytochrome b5 or b5 reductase alone or with cytochrome P450 reductase alone or with cytochrome b5. These results indicate that cytochrome b5 and b5 reductase play a direct role in metabolic activation of DB289 to furamidine.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0090-9556
pubmed:author
pubmed:issnType
Print
pubmed:volume
33
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1886-93
pubmed:dateRevised
2006-11-29
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Unusual dehydroxylation of antimicrobial amidoxime prodrugs by cytochrome b5 and NADH cytochrome b5 reductase.
pubmed:affiliation
School of Pharmacy, University of North Carolina at Chapel Hill, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't