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Chemopreventive effect of dietary flavonoid morin on chemically induced rat tongue carcinogenesis
Author(s) -
Kawabata Kunihiro,
Tanaka Takuji,
Honjo Shiro,
Kakumoto Mikio,
Hara Akira,
Makita Hiroki,
Tatematsu Norichika,
Ushida Jun,
Tsuda Hiroyuki,
Mori Hideki
Publication year - 1999
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/(sici)1097-0215(19991029)83:3<381::aid-ijc14>3.0.co;2-x
Subject(s) - morin , tongue , 4 nitroquinoline 1 oxide , medicine , endocrinology , flavonoid , carcinogenesis , tongue neoplasm , glutathione , biology , chemistry , enzyme , antioxidant , biochemistry , pathology , cancer
The modifying effects of dietary exposure of the flavonoid morin on 4‐nitroquinoline 1‐oxide (4‐NQO)‐induced tongue tumorigenesis, the activities of phase II detoxifying enzymes glutathione S ‐transferase (GST) and quinone reductase (QR) in liver and tongue, and cell proliferation activity in tongue were investigated in male F344 rats. At 7 weeks of age, all animals except those treated with morin alone and control group were given 4‐NQO (20 ppm) in drinking water for 8 weeks to induce oral neoplasms. Starting 7 days before 4‐NQO exposure, experimental groups were fed experimental diets containing morin (100 and 500 ppm) for 10 weeks (“initiation feeding”). Starting 1 week after the cessation of exposure to 4‐NQO, other experimental groups given 4‐NQO and a basal diet were given experimental diets for 22 weeks (“post‐initiation feeding”). At week 32 week, “initiation feeding” of morin caused a significant reduction in the incidence of tongue carcinoma (by 44–100%). “Post‐initiation feeding” with morin also significantly decreased the frequency of tongue carcinoma (by 44%). Morin feeding elevated liver GST and QR activities and GST activity in the anterior portion of tongue. Feeding with morin significantly lowered QR activity of the posterior part of the tongue. Dietary exposure to morin significantly decreased the proliferating cell nuclear antigen‐positive index in the posterior portion. Also, morin feeding lowered tongue polyamine levels, especially in the “post‐initiation feeding” group. Our results indicate that morin acts as a chemopreventive agent against tongue carcinogenesis induced by 4‐NQO through modification of detoxifying enzyme activities and/or cell proliferation activities. Int. J. Cancer 83:381–386, 1999. © 1999 Wiley‐Liss, Inc.