In vitro interaction of 7,12-dimethylbenz[a]anthracene and its biliary metabolites with dietary fiber.

Abstract

This in vitro study examined the ability of various dietary fiber components to bind 7,12-dimethylbenz[a]anthracene (DMBA), a hydrocarbon carcinogen known to contaminate food. Bile salt solutions of DMBA were incubated with individual fiber materials under various conditions, and the degree of binding was assessed. Binding of DMBA from simple bile salt solution was greatest with delipidated bran greater than acid lignin greater than alpha-cellulose greater than unprocessed bran. Binding to acid lignin was slowly reversible, was constant within the pH range 4-8, and appeared independent of a bile salt-fiber interaction. Acid lignin bound DMBA from a mixed lipid-bile salt solution significantly, but less effectively than from pure bile salt solutions. DMBA biliary metabolites from Sprague-Dawley rats were bound less extensively to all the fiber materials than was the parent hydrocarbon, but following hydrolysis of the metabolites by beta-glucuronidase binding was significantly increased. These results indicate that there is considerable potential for dietary fiber to interact with DMBA and its metabolites in the lumen of the gastrointestinal tract, possibly influencing hydrocarbon carcinogen bioavailability.