Auraptene, a citrus coumarin, inhibits 12-O-tetradecanoylphorbol-13-acetate-induced tumor promotion in ICR mouse skin, possibly through suppression of superoxide generation in leukocytes

Akira Murakami, Wataru Kuki, Yasuo Takahashi, Hiroshi Yonei, Yoshimasa Nakamura, Yoshimi Ohto, Hajime Ohigashi, Koichi Koshimizu

Research output: Contribution to journalArticle

151 Citations (Scopus)

Abstract

Coumarin-related compounds, auraptene and umbelliferone, have been isolated from the cold-pressed oil of natsumikan (Citrus natsudaidai HAYATA), and tested as inhibitors of tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced Epstein-Barr virus activation in Raji cells. The 50% inhibitory concentration (IC50) of auraptene (18 μM) was almost equal to that of genistein. Umbelliferone, which lacks a geranyloxyl group present in auraptene, was less active (IC50 = 450 μM). In a two-stage carcinogenesis experiment with 7,12-dimethylbenz[a]anthracene (topical application at 0.19 μmol) and TPA (topical application at 1.6 nmol) in ICR mouse skin, topical application of auraptene (at 160 nmol) significantly reduced tumor incidence and the numbers of tumors per mouse by 27% (P < 0.01) and 23% (P < 0.05), respectively. Auraptene at a concentration of 50 μM markedly suppressed superoxide (O2-) generation induced by 100 nM TPA in differentiated human promyelocytic HL-60 cells. Having no O2--scavenging potential, auraptene may inhibit the multicomponent NADPH oxidase system. Inhibition of intracellular hydroperoxide formation in differentiated HL-60 cells by auraptene was also confirmed by flow-cytometric analysis using 2',7'-dichlorofluorescein diacetate as a fluorescence probe. Quantitative analyses using high-performance liquid chromatography showed the occurrence of auraptene not only in both the peels and sarcocarps of natsumikan, but also in those of hassaku orange (C. hassaku) and grapefruit (C. paradisi), and even in their bottled fresh juice form. These results indicate that auraptene is a chemopreventer of skin tumorigenesis, and implies that suppression of leukocyte activation might be the mechanism through which it inhibits tumor promotion.

Original languageEnglish
Pages (from-to)443-452
Number of pages10
JournalJapanese Journal of Cancer Research
Volume88
Issue number5
DOIs
Publication statusPublished - May 1997
Externally publishedYes

Keywords

  • Anti-tumor promoter
  • Auraptene
  • Chemoprevention
  • Citrus coumarin
  • Superoxide

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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