Light-dependent inhibition of protein kinase c and superoxide generation of neutrophils by hypericin, an antiretroviral agent

Takahiko Utsumi, Minoru Okuma, Toshihiko Utsumi, Tomoko Kanno, Tatsuji Yasuda, Hirotsugu Kobuchi, Alan A. Horton, Kozo Utsumi

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

Hypericin, a photosensitizing plant pigment, has antiretroviral activity. When exposed to light, the inhibition of Friend leukemia virus (FLV)-induced splenomegaly by hypericin was increased. The ID50 was decreased to less than 2.5 μg/mouse by exposure to tungsten light (29 × 10-3 W/cm2 for 3 min). This pigment inhibited phorbol 12-myristate 13-acetate (PMA)-activated protein kinase C of rat brain in a light- and concentration-dependent manner. The ID50 of hypericin and the light intensity for inhibition of PKC were 0.1 μM under a constant light of 29 × 10-3 W/cm2 for 3 min and 5 × 10-3 W/cm2 in the presence of 1 μM hypericin for 3 min, respectively. The PMA-induced respiratory burst of neutrophils was inhibited in the light but stimulated in the dark by hypericin. The ID50 for inhibition of the respiratory burst was similar to that for inhibition of PKC. These results suggest that hypericin might inhibited PKC-mediated processes of intact cells, including PMA-induced superoxide generation of neutrophils by some light-dependent mechanism, and that this mechanism might underlie its light-dependent inhibition of FLV infection.

Original languageEnglish
Pages (from-to)493-497
Number of pages5
JournalArchives of Biochemistry and Biophysics
Volume316
Issue number1
DOIs
Publication statusPublished - Jan 1995
Externally publishedYes

Keywords

  • Antiretroviral pigment
  • Hypericin
  • Neutrophil O— generation
  • PKC
  • Photoactivated inhibition

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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