Quantification of modified tyrosines in healthy and diabetic human urine using liquid chromatography/tandem mass spectrometry

Yoji Kato, Natsuko Dozaki, Toshiyuki Nakamura, Noritoshi Kitamoto, Akihiro Yoshida, Michitaka Naito, Masayasu Kitamura, Toshihiko Osawa

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53 Citations (Scopus)


The quantification of urinary oxidized tyrosines, dityrosine (DiY), nitrotyrosine (NY), bromotyrosine (BrY), and dibromotyrosine (DiBrY), was accomplished by quadruple liquid chromatography-tandem mass spectrometry (LC/MS/MS). The sample was partially purified by solid phase extraction, and was then applied to the LC/MS/MS using multiple-reaction monitoring (MRM) methods. The analysis for the DiY quantification was done first. The residual samples were further butylated with n-butanol/HCI, and the other modified tyrosines were then quantified with isotopic dilution methods. MRM peaks of the modified tyrosines (DiY, NY, BrY, and DiBrY) from human urine were measured and the elution times coincided with the authentic and isotopic standards. The amounts of modified tyrosines in healthy human urine (n = 23) were 8.8 ± 0.6 (D1Y), 1.4 ± 0.4 (NY), 3.8 ± 0.3 (BrY), and 0.7 ± 0.1 (DiBrY) μmol/mol of creatinine, respectively. A comparison of the modified tyrosines with urinary 8-oxo-deoxyguanosine, pentosidine, and Nε-(hexanoyl)lysine was also performed. Almost all products, except for NY, showed good correlations with each other. The amounts of the modified tyrosines (NY, BrY, and DiBrY) in the diabetic urine were higher than those in the urine from healthy people.

Original languageEnglish
Pages (from-to)67-78
Number of pages12
Journaljournal of clinical biochemistry and nutrition
Issue number1
Publication statusPublished - Jan 2009
Externally publishedYes


  • Diabetes
  • Dityrosine
  • Halotyrosines
  • Nitrotyrosine
  • Urine

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics
  • Clinical Biochemistry


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