Identification of Coumarins from Lemon Fruit (Citrus limon) as Inhibitors of in Vitro Tumor Promotion and Superoxide and Nitric Oxide Generation

• Published in: Journal of agricultural and food chemistry Vol. 47; no. 8; pp. 3151 - 3157
• Main Authors: Miyake, Yoshiaki, Murakami, Akira, Sugiyama, Yukiteru, Isobe, Minoru, Koshimizu, Koichi, Ohigashi, Hajime
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.08.1999
• Subjects: Animals; antineoplastic agents; Antineoplastic Agents - isolation & purification; Antineoplastic Agents - toxicity; Antioxidants - isolation & purification; Antioxidants - pharmacology; Biological and medical sciences; Carcinogenesis, carcinogens and anticarcinogens; Cell Line; chemoprevention; Citrus - chemistry; Citrus limon; coumarins; Coumarins - chemistry; Coumarins - isolation & purification; Coumarins - pharmacology; Foods and miscellaneous; Free Radical Scavengers; Herpesvirus 4, Human - drug effects; Herpesvirus 4, Human - growth & development; HL-60 Cells; Human herpesvirus 4; Humans; identification; in vitro; Interferon-gamma - pharmacology; lemons; Lipopolysaccharides - pharmacology; Macrophages - drug effects; Macrophages - physiology; Medical sciences; Mice; Nitric Oxide - metabolism; peel; Plant Extracts - chemistry; Recombinant Proteins; Superoxides - metabolism; Tetradecanoylphorbol Acetate - pharmacology; Tumor Cells, Cultured; Tumors; Virus Activation - drug effects; Gammaherpesvirinae; Biochemical analysis; Bioassay; Fruit; Citrus fruit; Herpesviridae; Rutaceae; Epstein Barr virus; Anticarcinogen; Experimental study; Lemon; Coumarin; In vitro; Virus; Citrus limon; Dicotyledones; Nitric oxide; Angiospermae; Chemical protection; Spermatophyta; Inhibition; Tumor promotion
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf980999y

Three coumarins were isolated as siginificant inhibitors of tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced Epstein−Barr virus (EBV) activation in Raji cells from the peel of lemon fruit. They were identified as 8-geranyloxypsolaren (LE−1), 5-geranyloxypsolaren (bergamottin, LE−2), and 5-geranyloxy-7-methoxycoumarin (LE−3), respectively, by spectroscopic analysis. Three isolates had no potential O2-scavenging and markedly suppressed TPA-induced superoxide (O2 -) generation in differentiated human promyelocytic HL-60 cells. Furthermore, LE−1 and LE−3 reduced both lypopolysaccharide (LPS) and interferone-γ (IFN-γ)-induced nitric oxide (NO) generation in mouse macrophage RAW 264.7 cells. Similarly, they were found to be NO generation inhibitors rather than scavengers by measuring the extracellular l-citrulline levels. The occurrence of these coumarins in a lemon fruit was abundant in the flavedo of the peel based on quantitative analysis using high-performance liquid chromatography (HPLC). The present study suggests that the coumarins in lemon fruit are promising chemopreventive agents by inhibiting radical generation. Keywords: Citrus limon; coumarin; psoralen; chemopreventive agent; Epstein−Barr virus; superoxide; nitric oxide