Urinary excretion of tetrahydro-beta-carbolines relating to ingestion of alcoholic beverages.

Tetrahydro-beta-carbolines, formed from aldehydes and tryptamine, have been suggested as potential biochemical markers for alcoholism. The excretion of 1-methyl-1,2,3,4-tetrahydro-beta-carboline (MTBC) and 1,2,3,4-tetrahydro-beta-carboline (TBC) in human urine was studied to assess their possible origin. In urine collected after a drinking party, MTBC and TBC were excreted in significantly higher concentrations compared with sobriety. MTBC and TBC were contained in beer and wine at ng/ml levels, but not in distillate alcoholic beverages such as whisky, brandy, gin, etc. The urinary excretion of MTBC and TBC was elevated after drinking beer, whereas no change was observed after drinking whisky. When a human subject was orally administered with deuterated L-tryptophan together with drinking whisky, deuterated tryptamine was increasingly excreted in urine. However, no increase was found in urinary deuterated MTBC. These results indicate that the urinary excretion of MTBC and TBC associated with alcohol ingestion does not imply promotion of their in vivo formation, but the exogenous supply of MTBC and TBC by drinking alcoholic beverages containing them.