ABSTRACT
Flavonoids are distributed in many plants. We studied the antitumor effects of flavonoids isolated from Viticis Fructus, casticin, artemetin, quercetagetin and 5,3'-dihydroxy-6,7,4' -trimethoxyflavanone. Casticin inhibited the growth of KB cells markedly (IC(50)=0.23 microM), compared with the other flavonoids tested (IC(50)=15.3-18.6 microM). In contrast, casticin did not inhibit the proliferation of A431 cells similar to normal cell lines, 3T3 Swiss Albino and TIG-103. Flow cytometric analyses revealed that the exposure of KB cells to casticin led to significant arrest at G2-M. In immunostaining of KB cells, casticin disrupted mitotic spindles. These results suggest that G2-M arrest by casticin may be relevant to its antimitotic activity, although the mechanism of selective growth inhibition has been unknown. Further examinations are required to confirm that casticin is an antitumor drug for specific cancers with low toxicity.
Subject(s)
Carcinoma, Squamous Cell/pathology , Flavonoids/pharmacology , G2 Phase/drug effects , Mitosis/drug effects , Vitex/chemistry , Aldehyde Reductase/antagonists & inhibitors , Animals , Carcinoma, Squamous Cell/metabolism , Cell Division/drug effects , Cells, Cultured , Chromones/pharmacology , Flavones , Flavonoids/isolation & purification , Humans , KB Cells , Mice , Spindle Apparatus/drug effects , Swiss 3T3 CellsABSTRACT
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.
