Reversible binding of the cooked food mutagen MeIQx to lignin-enriched preparations from wheat bran

The binding of the mutagen 3,8-dimethyl-3H-imidazo[4,5-f]quinoxaline-2-amine (MeIQx) to various fibre preparations from wheat bran was studied. The physical structures of wheat bran and lignin-enriched preparations were determined by scanning electron microscopy. With increasing mutagen concentration from 0.5-16 micrograms/ml, the fraction of MeIQx bound to cellulase-treated lignin was nearly constant, for a certain lignin density. The binding between cellulase-treated lignin and MeIQx was reversible. Incubation temperature influenced the rate at which the equilibrium between lignin and MeIQx was established, but had less effect on the equilibrium itself. With increasing fibre densities and a constant mutagen concentration, complete binding was apparently reached at a high fibre density. This was illustrated by plotting the data according to Scatchard. Increased binding of the MeIQx was obtained with increased enrichment of lignin in different fibre preparations.