Presence of tetrahydro-beta-carboline-3-carboxylic acids in foods by gas chromatography-mass spectrometry as their N-methoxycarbonyl methyl ester derivatives.

T Herraiz, F Sanchez

Index: J. Chromatogr. A. 765(2) , 265-77, (1997)

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Abstract

Various tetrahydro-beta-carboline-3-carboxylic acids (TH beta C-3-COOH) are identified in commercial foods and drinks by GC-MS. Positive identification of 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid (MTCA) is demonstrated in soy and tabasco sauces, wine, beer, wine vinegar, cider, orange juice, toasted bread, blue cheese and yoghurt. 1,2,3,4-Tetrahydro-beta-carboline-3-carboxylic acid (THCA) occurs in toasted bread, beer, cider, wine vinegar, soy and tabasco sauce, orange juice and blue cheese. MTCA and THCA are reported for the first time in several of these products. MTCA appears as a mixture of two diastereoisomers with the same mass spectra. MTCA is the major TH beta C-3-COOH in foodstuffs except for toasted bread that contains more THCA. GC-MS analysis of N-methoxycarbonyl methyl ester derivatives of TH beta C-3-COOHs was used for chemical identification. Those derivatives were synthesized in a qualitatively using methyl chloroformate or methyl chloroformate and diazomethane reagents. Electron impact mass spectra of N-methoxycarbonyl-TH beta C-3-COOH methyl esters are reported and fragmentation assigned and discussed. These results prove the presence of TH beta C-3-COOHs in commercial foodstuffs suggesting their uptake during the daily consumption of foods.