ROLE OF COLON MUCOSA CYTOCHROME P450 IN ACTIVATION OF CARCINOGEN AND THEIR INDUCTION AND INHIBITION

The data presented in this report indicate that rat colon mucosa microsome contain a competent mixed function oxidase system depended on cytochrome P450. The colon enzymatic system catalyze the hydroxylation of the model colon carcinogen 1, 2—dimethylhydrazine(DMH). DMH is hydroxylated by colon system at rate 79.5％ of the rate catalyzed by liver system. The colon system's hydroxylation activity and cytochrome P450 content can he induced by pretreatment with phenobarbital and can be inhibited by pretreatment with vitamin E. The experiment suggests important role of colon mucosa cytoehrome P450 in activation of carcinogen and possibility of vitamin E in protection of large bowel chemical carcinogenesis.