Reaction of Tryptophan with Carbohydrates:  Identification and Quantitative Determination of Novelβ-Carboline Alkaloids in Food

Abstract

The formation of various carbohydrate-derived beta-carbolines was observed when model reactions of tryptophan with glucose were studied by means of HPLC with diode array detection, as well as by means of HPLC-MS. Isolation of these compounds and subsequent characterization by tandem mass spectrometry and NMR spectroscopy led to the identification of diastereomeric 1-(1,3,4,5-tetrahydroxypent-1-yl)-9H-pyrido[3,4-b]indoles (1a/b), 1-(1,4,5-trihydroxypent-1-yl)-9H-pyrido[3,4-b]indoles (2a/b), and E/Z isomers of 1-(1,5-dihydroxypent-3-en-1-yl)-9H-pyrido[3,4-b]indole (3a/b). HPLC-MS was used to prove the presence of these novel beta-carboline alkaloids in various food samples. In addition, quantitative determination of beta-carbolines 1a, 1b, and 2a/b in numerous products was achieved by means of HPLC with fluorometric detection. Concentrations ranged from 12 to 1922 microg/L for 1a and 1b and from 3 to 644 microg/L for 2a/b. The highest concentrations of all carbohydrate-derived beta-carbolines under study were found in ketchup, soy sauce, and fish sauce.

Mass Spectrometry–Based Analysis of Urinary Biomarkers for Dietary Tomato Intake

“…Evidently, Tan E and Tan F were still quantifiable in urine even after 3 days of abstaining from tomato products, with the respective concentrations determined in all blank urine samples being however quite low (Figure 3). As the occurrence of these alkaloids was shown to be highest in tomato products but further shown in several other food commodities in lower levels, [15,22] these findings are expectable. Other foods primarily contributing to the elevated urine levels of these -carboline alkaloids are most likely beer, coffee, and cereal products.…”

The intermolecular Pictet-Spengler condensation with chiral carbonyl derivatives in the stereoselective syntheses of optically-active isoquinoline and indole alkaloids

“…In addition, Wang and co-workers identified 1-(1,3,4-trihydroxybutyl)-β-carboline (14) and 1-(1,4-dihydroxy butyl)-β-carboline (15) in model reactions of tryptophan with xylose 40 and the group of Herderich has recently identified numerous hexose-and pentose-derived β-carbolines in food samples 41 and studied the formation pathway of these novel alkaloids. 42 According to Wang, the formation of compounds 14 and 15 from tryptophan and xylose, involves a sequence including Pictet-Spengler condensation, oxidative decarboxylation, tautomerization, and dehydrogenation steps, a mechanism in which isomerization of the sugarderived side chain at C-1' is essential.…”

Formation and stability of heterocyclic amines in a meat flavour model system

“…Pyrolisis of tryptophan and glutamic acid, leads to the formation of Trp-P-1, Trp-P-2, Glu-P-1 and Glu-P-2 [5]. The comutagens harman and norharman are found in dry-model systems containing tryptophan and glucose and are easily formed, even at temperatures lower than 100 • C [6,7]. Mixtures of glucose, creatinine and amino acids, such as glycine, alanine, lysine, methionine, phenylalanine and threonine heated at different temperatures in diethylenglycol and water, and also in some cases in dry conditions, allow the formation of MeIQ, IQ, IQx, MeIQx, 4,8-DiMeIQx, 7,8-DiMeIQx and PhIP [8][9][10][11][12][13][14].…”