title: Quercetin enhances tumorigenicity induced by N-ethyl-N'-nitro-N-nitrosoguanidine in the duodenum of mice.
abstract: Quercetin, a flavonoid, widely distributed in many fruits and vegetables, is well known to have an antitumor effect despite its mutagenicity. In this study, we examined the effect of dietary quercetin on duodenum-tumorigenicity of mice induced by a chemical carcinogen, N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG). Eight-week-old male C57BL/6 mice were divided into 4 groups; ENNG without quercetin (group A), ENNG with 0.2% quercetin (group B), ENNG with 2% quercetin (group C), and 2% quercetin without ENNG (group D). ENNG was given in drinking water for the first 4 weeks, and thereafter quercetin was given in a mixed diet. At week 20, the average number of duodenal tumors per mouse was significantly higher in group C (mean±SE, 7.26±1.75, p<0.05) than in group A (2.32±0.31). The size of the duodenal tumors increased significantly in group B (1.79±0.09 mm, p<0.001) compared with group A (1.43±0.09 mm). In contrast, no duodenal tumor was induced in group D. The present findings suggest that excessive intake of quercetin occasionally is a risk factor for carcinogenesis of some specific organs such as the upper intestine.
authors: Department of Preventive Medicine, Kyoto Prefectural University of Medicine, Kyoto.
authors: Yoshizumi
authors: Y
authors: Matsukawa
authors: Hoyoku
authors: H
authors: Nishino
authors: Mitsunori
authors: M
authors: Yoshida
authors: Hiroyuki
authors: H
authors: Sugihara
authors: Kanade
authors: K
authors: Katsura
authors: Tetsurou
authors: T
authors: Takamatsu
authors: Junichi
authors: J
authors: Okuzumi
authors: Katsuhiko
authors: K
authors: Matsumoto
authors: Fumiko
authors: F
authors: Sato-Nishimori
authors: Toshiyuki
authors: T
authors: Sakai