5,5-dimethyl-1-pyrroline-N-oxide alone enhances the spontaneous superoxide generation by primaquine

László Prónai, Kohji Ichimori, Yoshinori Saigusa, Hiroe Nakazawa

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3 Citations (Scopus)


Primaquine (PQ), a well-known antimalarial drug, has been reported to generate superoxide (O2-) in the presence of reducing agents such as NADPH. In the present study, chemiluminescence was detected by adding only PQ to aqueous 2-methyl-6-[p-methoxyphenyl]-3,7-dihydroimidazo-[1,2-α]pyrazin-3-one (MCLA), which is a specific chemiluminescent probe for O2-, and was quenched by superoxide dismutase (SOD), indicating that PQ alone can generate O2- in aerobic conditions. Furthermore, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) enhanced the O2- generation by PQ. Superoxide spin adduct, DMPO-OOH, was also detected by ESR both in aqueous solutions and in dimethyl sulfoxide with DMPO. The level of O2- generation showed a linear correlation with the DMPO concentration, and SOD competitively inhibited the DMPO-OOH formation. The results suggested that in aerobic conditions PQ is autoxidized to 5-hydroxy-PQ, which generates O2-, and DMPO accelerates the autoxidation process by trapping O2-. DMPO or M4PO alone enhances the spontaneous O2- generation by PQ, therefore cautious evaluation is necessary in all studies using the ESR/spin trapping technique to elucidate the mechanism of PQ-related radical generation.

Original languageEnglish
Pages (from-to)276-281
Number of pages6
JournalArchives of Biochemistry and Biophysics
Issue number1
Publication statusPublished - Jul 1991


ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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