Inhibition of intestinal carcinogenesis by a new flavone derivative, chafuroside, in oolong tea

Abstract

A new flavone derivative, chafuroside, has been isolated as a strong anti-inflammatory compound from oolong tea leaves, and its structure determined to be (2R,3S,4S,4aS,11bS)-3,4,11-trihydroxy-2-(hydroxymethyl)-8-(4-hydroxyphenyl)-3,4,4a,11b-tetrahydro-2H,10H-pyrano[2',3':4,5]furo[3,2-g]chromen-10-one. To assess its potential to inhibit intestinal carcinogenesis, 2.5, 5 and 10 p.p.m. chafuroside was given in the diet to Apc-deficient Min mice for 14 weeks from 6 weeks of age. Total numbers of polyps were reduced to 83, 73 and 56% of the control value, respectively. Moreover, dietary administration at 10 and 20 p.p.m. reduced azoxymethane (AOM)-induced colon aberrant crypt foci (ACF) development in rats to 69% of the AOM-treated control value with the higher dose. Chafuroside-associated toxicity was not observed at 2.5-10 p.p.m. in Min mice and 10-20 p.p.m. in AOM-treated rats. These results suggest that chafuroside might be a good chemopreventive agent for colon cancer.

Figure 1

Structure of chafuroside.

Figure 2

Effects of chafuroside on the size distribution of intestinal polyps in Min mice. Min mice were fed a basal diet (▪) or a diet containing 2.5 (□), 5 (▨) or 10 p.p.m. () chafuroside for 14 weeks. The number of polyps/mouse in each size class is given as a mean value (bars represent SD). *P < 0.05, **P < 0.01.