Metabolism of 5-flourouracil to an N-cholyl-2-fluoro-β-alanine conjugate

Previously unrecognized role for bile acids in drug conjugation

D. J. Sweeny, S. Barnes, G. D. Heggie, Robert B Diasio

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Recently we demonstrated clinically significant levels of a previously unrecognized metabolite of the anticancer drug 5-fluorouracil (FUra) in bile of cancer patients. In the present study, reanalysis of bile from these patients demonstrated the presence of not one but two previously unrecognized metabolites. The major unrecognized metabolite was purified by reversed-phase HPLC, after which its molecular weight was determined by fast-atom-bombardment mass spectrometry to be 497. The similarity in HPLC retention times and molecular weights of this FUra derivative and the bile acids N-cholylglycine (M(r) 465) and N-cholyltaurine (M(r) 515), along with the structural similarity of the FUra catabolite 2-fluoro-β-alanine and the amino acids glycine and taurine, led to the hypothesis that this metabolite could be a conjugate of 2-fluoro-β-alanine and cholic acid. This hypothesis was tested and confirmed by hydrolyzing the purified metabolite by cholylglycine hydrolase after which: (i) 2-fluoro-β-alanine was demonstrated by using a sensitive HPLC technique capable of resolving all of the known putative FUra metabolites, and (ii) unconjugated cholic acid was identified by both GC and GC-MS. Additionally, chemically synthesized N-cholyl-2-fluoro-β-alanine was shown to cochromatograph on HPLC and TLC with the purified biliary metabolite. In summary, this study demonstrates a unique, so far as we know, pathway of drug metabolism in man in which an amino acid drug metabolite is conjugated with cholic acid and eliminated into the bile. Furthermore, the finding that 2-fluoro-β-alanine is conjugated to bile acids may provide some insight into the mechanism of cholestasis that is frequently observed after administration of fluoropyrimidine by hepatic arterial infusion.

Original languageEnglish (US)
Pages (from-to)5439-5443
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume84
Issue number15
StatePublished - 1987
Externally publishedYes

Fingerprint

Bile Acids and Salts
Alanine
Cholic Acid
Fluorouracil
High Pressure Liquid Chromatography
Bile
Pharmaceutical Preparations
choloylglycine hydrolase
Molecular Weight
Glycocholic Acid
Fast Atom Bombardment Mass Spectrometry
Amino Acids
Taurocholic Acid
Taurine
Cholestasis
Glycine
Liver
Neoplasms

ASJC Scopus subject areas

  • General
  • Genetics

Cite this

@article{4e5868b05135497f8498f4b9c1eafe54,
title = "Metabolism of 5-flourouracil to an N-cholyl-2-fluoro-β-alanine conjugate: Previously unrecognized role for bile acids in drug conjugation",
abstract = "Recently we demonstrated clinically significant levels of a previously unrecognized metabolite of the anticancer drug 5-fluorouracil (FUra) in bile of cancer patients. In the present study, reanalysis of bile from these patients demonstrated the presence of not one but two previously unrecognized metabolites. The major unrecognized metabolite was purified by reversed-phase HPLC, after which its molecular weight was determined by fast-atom-bombardment mass spectrometry to be 497. The similarity in HPLC retention times and molecular weights of this FUra derivative and the bile acids N-cholylglycine (M(r) 465) and N-cholyltaurine (M(r) 515), along with the structural similarity of the FUra catabolite 2-fluoro-β-alanine and the amino acids glycine and taurine, led to the hypothesis that this metabolite could be a conjugate of 2-fluoro-β-alanine and cholic acid. This hypothesis was tested and confirmed by hydrolyzing the purified metabolite by cholylglycine hydrolase after which: (i) 2-fluoro-β-alanine was demonstrated by using a sensitive HPLC technique capable of resolving all of the known putative FUra metabolites, and (ii) unconjugated cholic acid was identified by both GC and GC-MS. Additionally, chemically synthesized N-cholyl-2-fluoro-β-alanine was shown to cochromatograph on HPLC and TLC with the purified biliary metabolite. In summary, this study demonstrates a unique, so far as we know, pathway of drug metabolism in man in which an amino acid drug metabolite is conjugated with cholic acid and eliminated into the bile. Furthermore, the finding that 2-fluoro-β-alanine is conjugated to bile acids may provide some insight into the mechanism of cholestasis that is frequently observed after administration of fluoropyrimidine by hepatic arterial infusion.",
author = "Sweeny, {D. J.} and S. Barnes and Heggie, {G. D.} and Diasio, {Robert B}",
year = "1987",
language = "English (US)",
volume = "84",
pages = "5439--5443",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
number = "15",

}

TY - JOUR

T1 - Metabolism of 5-flourouracil to an N-cholyl-2-fluoro-β-alanine conjugate

T2 - Previously unrecognized role for bile acids in drug conjugation

AU - Sweeny, D. J.

AU - Barnes, S.

AU - Heggie, G. D.

AU - Diasio, Robert B

PY - 1987

Y1 - 1987

N2 - Recently we demonstrated clinically significant levels of a previously unrecognized metabolite of the anticancer drug 5-fluorouracil (FUra) in bile of cancer patients. In the present study, reanalysis of bile from these patients demonstrated the presence of not one but two previously unrecognized metabolites. The major unrecognized metabolite was purified by reversed-phase HPLC, after which its molecular weight was determined by fast-atom-bombardment mass spectrometry to be 497. The similarity in HPLC retention times and molecular weights of this FUra derivative and the bile acids N-cholylglycine (M(r) 465) and N-cholyltaurine (M(r) 515), along with the structural similarity of the FUra catabolite 2-fluoro-β-alanine and the amino acids glycine and taurine, led to the hypothesis that this metabolite could be a conjugate of 2-fluoro-β-alanine and cholic acid. This hypothesis was tested and confirmed by hydrolyzing the purified metabolite by cholylglycine hydrolase after which: (i) 2-fluoro-β-alanine was demonstrated by using a sensitive HPLC technique capable of resolving all of the known putative FUra metabolites, and (ii) unconjugated cholic acid was identified by both GC and GC-MS. Additionally, chemically synthesized N-cholyl-2-fluoro-β-alanine was shown to cochromatograph on HPLC and TLC with the purified biliary metabolite. In summary, this study demonstrates a unique, so far as we know, pathway of drug metabolism in man in which an amino acid drug metabolite is conjugated with cholic acid and eliminated into the bile. Furthermore, the finding that 2-fluoro-β-alanine is conjugated to bile acids may provide some insight into the mechanism of cholestasis that is frequently observed after administration of fluoropyrimidine by hepatic arterial infusion.

AB - Recently we demonstrated clinically significant levels of a previously unrecognized metabolite of the anticancer drug 5-fluorouracil (FUra) in bile of cancer patients. In the present study, reanalysis of bile from these patients demonstrated the presence of not one but two previously unrecognized metabolites. The major unrecognized metabolite was purified by reversed-phase HPLC, after which its molecular weight was determined by fast-atom-bombardment mass spectrometry to be 497. The similarity in HPLC retention times and molecular weights of this FUra derivative and the bile acids N-cholylglycine (M(r) 465) and N-cholyltaurine (M(r) 515), along with the structural similarity of the FUra catabolite 2-fluoro-β-alanine and the amino acids glycine and taurine, led to the hypothesis that this metabolite could be a conjugate of 2-fluoro-β-alanine and cholic acid. This hypothesis was tested and confirmed by hydrolyzing the purified metabolite by cholylglycine hydrolase after which: (i) 2-fluoro-β-alanine was demonstrated by using a sensitive HPLC technique capable of resolving all of the known putative FUra metabolites, and (ii) unconjugated cholic acid was identified by both GC and GC-MS. Additionally, chemically synthesized N-cholyl-2-fluoro-β-alanine was shown to cochromatograph on HPLC and TLC with the purified biliary metabolite. In summary, this study demonstrates a unique, so far as we know, pathway of drug metabolism in man in which an amino acid drug metabolite is conjugated with cholic acid and eliminated into the bile. Furthermore, the finding that 2-fluoro-β-alanine is conjugated to bile acids may provide some insight into the mechanism of cholestasis that is frequently observed after administration of fluoropyrimidine by hepatic arterial infusion.

UR - http://www.scopus.com/inward/record.url?scp=0023390432&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0023390432&partnerID=8YFLogxK

M3 - Article

VL - 84

SP - 5439

EP - 5443

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 15

ER -