The effects of pH and bile salts on the binding of MeIQx to wheat bran fibre.

The effects of pH and of the bile salts, sodium cholate, chenodeoxycholate, taurocholate, deoxycholate and glycodeoxycholate on the adsorption of the heterocyclic aromatic amine mutagen and carcinogen 2-amino-3,8-dimethylimidazo[4,5-f]-quinoxaline (MeIQx) onto wheat bran cell wall material have been examined. The highest binding affinity of MeIQx for bran was at pH 5.5. Binding affinity declined more rapidly with pH > 5.5 than with pH < 5.5. Bile salts in solution did not appreciably affect the binding of MeIQx to bran, but where the bile salts formed a suspension then the adsorption was reduced. Where precipitation of bile salts occurred then the free concentration of MeIQx was also reduced, indicating that MeIQx binding/immobilization could be enhanced through interaction with bile salts.