Identification of phenylbutyrylglutamine, a new metabolite of phenylbutyrate metabolism in humans.
Phenylbutyrate is used in humans for treating inborn errors of ureagenesis, certain forms of cancer, cystic fibrosis and thalassemia. The known metabolism of phenylbutyrate leads to phenylacetylglutamine, which is excreted in urine. We have identified phenylbutyrylglutamine as a new metabolite of phenylbutyrate in human plasma and urine. We describe the synthesis of phenylbutyrylglutamine and its assay by gas chromatography/mass spectrometry as a tert-butyldimethylsilyl or methyl derivative, using standards of [(2)H(5)]phenylbutyrylglutamine and phenylpropionylglutamine. After administration of phenylbutyrate to normal humans, the cumulative urinary excretion of phenylacetate, phenylbutyrate, phenylacetylglutamine and phenylbutyrylglutamine amounts to about half of the dose of phenylbutyrate. Thus, additional metabolites of phenylbutyrate are yet to be identified.
Comte
Blandine
B
Department of Nutrition, Case Western Reserve University, Cleveland, Ohio 44106, USA.
Kasumov
Takhar
T
Pierce
Bradley A
BA
Puchowicz
Michelle A
MA
Scott
Mary-Ellen
ME
Dahms
Williams
W
Kerr
Douglas
D
Nissim
Itzhak
I
Brunengraber
Henri
H
D000284:Administration, Oral; D000328:Adult; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D005973:Glutamine / Q000031:analogs & derivatives* / Q000097:blood / Q000138:chemical synthesis / Q000302:isolation & purification* / Q000493:pharmacokinetics / Q000652:urine; D006801:Humans; D008297:Male; D015394:Molecular Structure; D010648:Phenylacetates / Q000493:pharmacokinetics; D010654:Phenylbutyrates / Q000008:administration & dosage / Q000493:pharmacokinetics*; D011355:Prodrugs / Q000493:pharmacokinetics*
D010648:Phenylacetates; D010654:Phenylbutyrates; D011355:Prodrugs; C463300:phenylbutyrylglutamine; D005973:Glutamine; C003089:phenylacetylglutamine; C025136:phenylacetic acid