Magnetic microcapsule exploration in the gastrointestinal cavity of the origins of colorectal cancer-associated DNA-damaging agents in the human diet.

Magnetically recoverable, semipermeable microcapsules have been devised for covalent entrapment of reactive substances in the intestinal cavity to biomonitor potentially DNA-damaging agents and the effects of etiologically important components of the human diet. These microcapsules have been shown to trap five types of agents in vivo, namely, carcinogen electrophiles, nitrosating agents, mutagens/carcinogens having a planar molecular structure, and as-yet unidentified endogenous cross-linking agents and precursors of reactive oxygen species. Substantial alterations in both total metabolites and types of metabolites trapped from [14C]benzo(a)pyrene were found to be caused by increasing (within the human intake range) the dietary levels of beef protein and dietary fiber. The system thus responds to a variety of potentially critical agents and in a manner consistent with epidemiologically important dietary modulators for colorectal carcinogenesis. Work toward recognizing entrapped endogenous agents has also begun.