Photoactivated inhibition of superoxide generation and protein kinase C activity in neutrophils by blepharismin, a protozoan photodynamically active pigment

Yoshiya Watanabe, Keisuke E-ige, Hirotsugu Kobuchi, Yoji Kato, Tatsuomi Matsuoka, Toshihiko Utsumi, Tamotsu Yoshioka, Alan A. Horton, Kozo Utsumi

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7 Citations (Scopus)


Blepharismin is an endogenous photosensitizing pigment found in the protozoan Blepharisma. This pigment inhibited the generation of Superoxide anion (O2-) in neutrophils not only via a diacylglycerol-induced protein kinase C (PKC)-dependent reaction but also by an arachidonate-induced PKC-independent reaction. The inhibition was light and concentration dependent for both reactions. Light-activated inhibition was strong at wavelengths between 520 and 570nm but not above 610nm. PKC activity in neutrophils and from rat brain was inhibited by blepharismin in a light- and concentration dependent manner. Moreover, arachidonate-activated NADPH oxidase activity in a cell-free system was also inhibited by the pigment in a light- and concentration-dependent manner. These results suggest that blepharismin inhibits NADPH oxidase activation through the non-specific inhibition of various membrane-bound enzymes and that this inhibition may also be correlated with that of PKC.

Original languageEnglish
Pages (from-to)529-536
Number of pages8
JournalBiochemical Pharmacology
Issue number4
Publication statusPublished - Feb 14 1995



  • NADPH-oxida se
  • active oxygen generation
  • enzyme inhibition
  • fluorescence of pigment
  • perylenequinones
  • tyrosine kinase

ASJC Scopus subject areas

  • Biochemistry
  • Pharmacology

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