Formation of tetrahydro-beta-carbolines in human saliva

When human saliva obtained after cigarette smoking was incubated in the presence of tryptamine, the formation of 1,2,3,4-tetrahydro-beta-carboline (TBC) and 1-methyl-1,2,3,4-tetrahydro-beta-carboline (MTBC) was observed in a short time. After incubation with tryptamine (2.5 micrograms/microliter) for 10 min, the concentrations of TBC and MTBC formed were 3.27 +/- 0.94 and 0.35 +/- 0.17 ng/microliter, respectively. The formation of TBC and MTBC in intact saliva and in saliva heated at 100 degrees for 10 min was compared, but no significant difference was found. The analysis of foodstuffs showed that significant amounts of tryptamine were contained in various foods and beverages. The analysis of cigarette smoke solutions and immersion solutions of denture-base acrylic resins showed that ng-micrograms/microliter levels of formaldehyde and acetaldehyde were contained in cigarette smoke and leached from dental resins. These results indicate that both precursors, tryptamine and aldehydes, coexist in oral environments and that their interaction to form TBC and MTBC potentially occurs in human saliva without participation of salivary enzyme.