Presence of kynurenic acid in alcoholic beverages - Is this good news, or bad news?

Kynurenic acid (KYNA) is a metabolite of tryptophan formed enzymatically along kynurenine pathway in bacteria, fungi, plants and animals. It was suggested that yeast may produce KYNA during the fermentation process. Since KYNA was found to interact with alcohol metabolism by inhibition of aldehyde dehydrogenase activity the aim of this study was to measure the content of KYNA in selected alcoholic beverages of various type, beer, wine, mead and spirits. Moreover, the absorption and elimination rate of KYNA administered as a beverage was investigated in humans. Twelve healthy volunteers (6 female and 6 male) were studied. Fifty six samples of alcoholic beverages were of commercial origin. KYNA was determined by means of high-performance liquid chromatography method with fluorometric detection. KYNA was identified in all studied beverages. The amounts of KYNA found in various types of beverages differed significantly: mead 9.4-38.1 mu g/100 ml, wine 1.4-10.9 mu g/100 ml, beer 0.1-5.2 mu g/100 ml, spirits 0.01-0.1 mu g/100 ml. In human, it was found that KYNA is rapidly absorbed from digestive tract reaching its maximal concentration in blood 30 min after administration. Thus, the potential interaction between KYNA and alcohol occurring in human body after ingestion of alcoholic beverages was proven.