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.
Department of Nutrition, Case Western Reserve University, Cleveland, Ohio 44106, USA.
Blandine
B
Comte
Takhar
T
Kasumov
Bradley A
BA
Pierce
Michelle A
MA
Puchowicz
Mary-Ellen
ME
Scott
Williams
W
Dahms
Douglas
D
Kerr
Itzhak
I
Nissim
Henri
H
Brunengraber
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