A bitter diterpenoid furanolactone columbin from Calumbae Radix inhibits azoxymethane-induced rat colon carcinogenesis

The modifying effect of dietary administration of a diterpenoid furanolactone columbin isolated from the crude drug Calumbae Radix (the root of Jateorhiza columba MIERS, Menispermacea) on azoxymethane (AOM)-induced was investigated in male F344 rats. Animals were initiated with AOM (three weekly subcutaneous injections of 15mg/kg body weight) to induce colonic neoplasms. They were fed the experimental diets mixed with columbin (4, 20, and 100ppm) for 4 weeks, starting 1 week before the first dosing of AOM and thereafter maintained on the basal diet without columbin. Additional experimental groups included the AOM alone group, the columbin alone group (100ppm in diet for 4 weeks), and the untreated control group. Dietary feeding of columbin (4, 20, and 100ppm) during the initiation phase of AOM-induced colon carcinogenesis reduced the incidence and multiplicity of colonic adenocarcinoma and the inhibition by feeding of 20ppm (incidence: 20%, P=0.0242 and multiplicity: 0.20±0.40, P