Sensitive determination of tyrosine metabolites, p-hydroxyphenylacetic acid, 4-hydroxy-3-methoxyphenyl-acetic acid and 4-hydroxy-3-methoxymandelic acid, by gas chromatography-negative-ion chemical-ionization mass spectrometry. Application to a stable isotope-labelled tracer experiment to investigate their metabolism in man.
A method has been established for studying the dynamic metabolism of tyrosine to its metabolites in humans using a deuterium-labelled amino acid. Phenylalanine-d5 was administered orally to human subjects (5 mg/kg) and the levels of p-hydroxyphenylacetic acid-d4, 4-hydroxy-3-methoxyphenylacetic acid-d3, and 4-hydroxy-3-methoxymandelic acid-d3 excreted into urine every hour were determined by gas chromatography-negative-ion chemical-ionization mass spectrometry. This method was also applied to some patients with depression and it was possible to detect a slight alteration in the excretion of some compounds compared with the control.
D002851:Chromatography, High Pressure Liquid; D003903:Deuterium; D008401:Gas Chromatography-Mass Spectrometry; D006719:Homovanillic Acid / Q000032:analysis* / Q000138:chemical synthesis; D006801:Humans; D010648:Phenylacetates / Q000032:analysis* / Q000138:chemical synthesis / Q000652:urine; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism*; D014642:Vanilmandelic Acid / Q000032:analysis* / Q000138:chemical synthesis / Q000652:urine
D010648:Phenylacetates; C026246:4-hydroxyphenylacetate; D014443:Tyrosine; D014642:Vanilmandelic Acid; D003903:Deuterium; D006719:Homovanillic Acid