Gingiva as a site for xenobiotic metabolism in rats.

NADPH-dependent N-demethylation of aminopyrine and tripelennamine and hydroxylation of aniline, phenytoin and tripelennamine occurred in rat gingival homogenates. The metabolic profile in gingiva appeared to be similar to that in liver, the major organ in the body for the metabolism of these xenobiotics.

Drug-nitrite interactions in human saliva: effects of food constituents on carcinogenic N-nitrosamine formation.

A simple and rapid high-pressure liquid chromatographic assay for monitoring N-nitrosodimethylamine (NDMA) in human saliva was developed. The method was used to study in vitro the effects of common food constituents on NDMA formation in saliva from the interaction of salivary nitrite with aminopyrine and oxytetracycline. Natural phenolic compounds, caffeic acid, and tannic acid, and synthetic additives, erythorbic acid, sorbic acid, propyl gallate, and butylated hydroxytoluene--all inhibited NDMA formation (20-80%). With ascorbic acid, up to 90% inhibition of NDMA synthesis in saliva was observed. In contrast, chlorogenic acid (a phenolic component of coffee) acted as a catalyst (up to 48% increase) of the nitrosamine formation under identical experimental conditions.