Generation mechanism of radical species by tyrosine-tyrosinase reaction

Mika Tada, Masahiro Kohno, Shigenobu Kasai, Yoshimi Niwano

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


Alleviated melanin formation in the skin through inhibition of tyrosine-tyrosinase reaction is one of the major targets of cosmetics for whitening ability. Since melanin has a pivotal role for photoprotection, there are pros and cons of inhibition of melanin formation. This study applying electron spin resonance (ESR)-spin trapping method revealed that .H and .OH are generated through tyrosine-tyrosinase reaction. When deuterium water was used instead of H2O, the signal of 5,5-dimethyl-1-pyrroline N-oxide (DMPO)-H (a spin adduct of DMPO and .H) greatly decreased, whilst DMPO-OH (a spin adduct of DMPO and .OH) did not. Thus, it is suggested that .H was derived from H2O, and .OH through oxidative catalytic process of tyrosine to dopaquinone. Our study suggests that tyrosinase inhibitors might contribute to alleviate the oxidative damage of the skin by inhibiting .OH generation via the enzyme reaction.

Original languageEnglish
Pages (from-to)162-166
Number of pages5
JournalJournal of Clinical Biochemistry and Nutrition
Issue number2
Publication statusPublished - 2010 Sep


  • Radical species
  • Tyrosinase
  • Tyrosine

ASJC Scopus subject areas

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


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