THE EFFECT OF COLUPULONE (A HOPS BETA-ACID) ON HEPATIC CYTOCHROME-P-450 ENZYMATIC-ACTIVITY IN THE RAT

Colupulone, a component of hops, was examined for its ability to alter rat hepatic cytochrome P-450 enzymatic activity, expression of hepati c cytochrome P-450 mRNA, and in vitro promutagen activation. Colupulon e was fed to male Sprague-Dawley rats for 5 days at 0.36% in the modif ied AIN 76 diet. Three cytochrome P-450 enzymatic activities were meas ured, and the corresponding steady-state mRNA levels were examined by Northern blot hybridization. Colupulone increased cytochrome P450IIB a nd P450IIIA steady-state mRNA levels. In vitro promutagen activation w as measured in the Ames assay using liver homogenates from each treatm ent group. Colupulone treatment did not alter the ex vivo cytochrome P -450-mediated activation of aflatoxin B-1 or benzo[a]pyrene to their m utagenic forms. The effect of long-term colupulone administration on i n vivo cytochrome P-450 enzymatic activity remains to be determined.