THE EFFECTS OF CARRAGEENAN ON DRUG-METABOLIZING ENZYME-SYSTEM ACTIVITIES IN THE GUINEA-PIG

Carrageenans are seaweed extracts comprising high molecular weight sulphated polygalactosides. They are used in foods at concentrations of up to 2.5% as thickening and gelling agents. When degraded to lower molecular weight forms, they have been shown to induce ulcerative colitis and colon cancer in laboratory animals. Furthermore, undergraded carrageenan (CG) has been shown to promote azoxymethane and methylnitrosourea initiated carcinogenesis, but the promotion mechanism is unclear. To determine if this mechanism involves alterations of tissue drug-metabolizing enzyme system (DMES) activities, six groups of five guinea-pigs each were administered 0.2% kappa undergraded, 0.2% iota undergraded, 1% kappa degraded or 1% iota degraded CG, or control solutions in the drinking-water for 8 wk. Microsomal and cytosolic DMES activities of the liver, small intestine and colon were determined. The kappa undergraded CG group exhibited significant (P < 0.05) increases in small intestine cytochrome P-450 levels and benzo[a]pyrene hydroxylase activities. These data suggest that undergraded CG may selectively induce DMES activities in the small intestine mucosa.