Chemopreventive Effects of Magnolia ovobata Extracts on Colonic Aberrant Crypt Foci Induced by 1,2-Dimethylhydrazine in F344 Rats

The chemopreventive effects of Magnolia ovobata water extract (MWE) and 70% ethanol extract (MEE) on the development of colonic aberrant crypt foci (ACF) induced by 1,2-dimethylhydrazine (DMH) were investigated. Six-week-old male F344 rats were divided to 7 experimental groups; 1) DMH alone, 2) DMH+0.3% MWE, 3) DMH+1% MWE, 4) DMH+3% MWE, 5) DMH+1% MEE, 6) 3% MWE alone and 7) normal control. Animals were subcutaneously injected with DMH (30 mg/kg) 4 times to induce colonic ACF during the initial 2 weeks, and fed with a basal containing various concentrations of test materials (MWE or MEE) for 8 weeks including the DMH-treatment period. The formation of ACF on colonic mucosa was observed after staining with methylene blue. There are no specific effects of MWE and MEE on body weight, feed and water consumptions, organ weights, histopathological observations, and hematological and blood chemistry analyses. Challenge with DMH alone induced mean number of 270.1 ACF/colon which was somewhat inhibited by MWE treatment, showing average numbers of 234.3-242.1 ACF/colon. In comparison, the ACF number was significantly suppressed to 216.5 by administration of 1% MEE. Therefore, these results suggest that Magnolia ovobata extracts, especially MEE, exert a chemopreventive effect on the DMH-induced colon cancer by inhibiting the early development of ACF.