INHIBITORY EFFECT OF COPTIDIS RHIZOMA AND SCUTELLARIAE RADIX ON AZOXYMETHANE-INDUCED ABERRANT CRYPT FOCI FORMATION IN RAT COLON

This study was conducted to obtain effective cancer chemopreventive ag ents with low toxicity from medicinal herbs. The effect of aqueous ext racts from 9 medicinal herbs with antiinflammatory effect were examine d on the formation of azoxymethane (AOM)-induced aberrant crypt foci ( ACF), putative preneoplastic lesions of the colon, Male F344 rats were treated with 15 mg/kg body weight of AOM once a week for two weeks. H erbal extract consisting of 2% of the diet was administered from 1 d p rior to the first carcinogen treatment. The number of AOM-induced ACF per colon was counted at 4 week. Extracts of Coptidis Rhizoma and Scut ellariae Radix significantly inhibited AOM-induced ACF formation. The number of ACF was decreased to 54% and 78% of that of the control by 2 % Coptidis Rhizoma and Scutellariae Radix extract in the diet, respect ively. Berberine and Baicalin, major ingredients of Coptidis Rhizoma a nd Scutellariae Radii, inhibited ACF formation at a dose equivalent to the amount in each herbal extract. Therefore, to investigate the mech anisms of action of berberine and baicalein which is the active substa nces of orally administered baicalin, their effects on cyclooxygenase 1 and 2 activities were studied. Berberine was found to inhibit cycloo xygenase 2 activity without inhibition of cyclooxygenase 1 activity, a nd baicalein inhibited cyclooxygenase 1 activity. Thus, Coptidis Rhizo ma and Scutellariae Radix suppressed experimental colon carcinogenesis , and their chemopreventive effects were explained from the inhibition of berberine on cyclooxygenase 2 activity and baicalein on cyclooxyge nase 1 activity.