Species absorbing in the 500-nm region in the reactions of pyridoxamine with pyrroloquinoline quinone and phenathrolinequinones

Yoshiko Nagata, Yoshikazu Matsushima, Noriko Fujii, Sumi Fukuda, Hideko Kanazawa, Reiko Yoda, Shigenobu Matsumoto

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1 Citation (Scopus)


Quinonoid species absorbing in the 500-nm region, which should serve as a model for the key intermediate in reactions catalyzed by pyridoxal phosphate enzymes, was formed in the reactions of pyridoxamine (PM) with pyrroloquinoline quinone (PQQ), 1,7-phenathroline-5,6-quinone and 4,7- phenathroline-5,6-quinone in alkaline methanol at 25δC. The band at around 500 nm appeared gradually and its intensity reached a maximum about 6h after initiation of the reaction, then decreased gradually and disappeared. 1,10- Phenathroline-5,6-quinone which lacks pyridine nitrogen peri to the o-quinone carbonyl groups did not react with primary amines under the conditions used. Crystalline product was prepared from PM and PQQ. Absorption spectra of its methanol and water solutions were similar to the spectrum formed from the reaction of PM and PQQ with 500 nm band assigned to the quinonoid. The results of FAB mass were consistent with the formula of the ketimine and the quinonoid formed from PM and PQQ.

Original languageEnglish
Pages (from-to)1774-1777
Number of pages4
JournalChemical and Pharmaceutical Bulletin
Issue number12
Publication statusPublished - 1999 Dec



  • 1,10-phenathroline- 5,6-quinone
  • 1,7- phenathroline-5,6-quinone
  • 4,7-phenathroline-5,6-quinone
  • Pyridoxamine
  • Pyrroloquinoline quinone
  • Quinonoid intermediate

ASJC Scopus subject areas

  • Chemistry(all)
  • Drug Discovery

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