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 15 mg/kg
body weight) to induce
colonic neoplasms. They were fed the experimental diets mixed with
columbin (4, 20, and 100 ppm) 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 (100 ppm in diet for 4 weeks), and the untreated control group. Dietary feeding of
columbin (4, 20, and 100 ppm) during the initiation phase of AOM-induced colon
carcinogenesis reduced the incidence and multiplicity of colonic
adenocarcinoma and the inhibition by feeding of 20 ppm (incidence: 20%, P=0.0242 and multiplicity: 0.20+/-0.40, P<0.02) and 100 ppm (incidence: 10%, P=0.0029 and multiplicity: 0.10+/-0.30, P<0.002)
columbin was significant when compared with the AOM alone group (incidence: 55% and multiplicity: 0.55+/-0.50). Also,
columbin administration in diet lowered the number of argyrophilic nucleolar organizer regions
protein per nucleus in non-lesional colonic crypts and the blood
polyamine content, which are reflected in cell proliferation activity. These results indicate chemopreventive ability of dietary
columbin against chemically induced colon
tumorigenesis when fed during the initiation phase, providing a scientific basis for chemopreventive ability of
columbin against human
colon cancer.