Related Experiment Video
Updated: Sep 2, 2026

Using Capillary Electrophoresis to Quantify Organic Acids from Plant Tissue: A Test Case Examining Coffea arabica Seeds
Published on: November 12, 2016
Comparative LC-MS Study of Colored Compounds Derived from Oxidative Coupling of Caffeic Acid Esters with α- or
Ann-Sophie Schweizer1, Maike Passon2, Andreas Schieber1
1Institute of Nutritional and Food Sciences, Molecular Food Technology, Faculty of Agricultural, Nutritional and Engineering Sciences, University of Bonn, Friedrich-Hirzebruch-Allee 7, Bonn53115, Germany.
Abstract:
Oxidative coupling of caffeic acid esters with primary amino compounds may cause the formation of colored compounds, but there is still uncertainty about the mechanisms and structures, especially when derived from α-amino acids. Therefore, methyl caffeate (MCA) or 5-caffeoylquinic acid (5-CQA) was reacted with either α- or β-alanine, and the products were characterized using UHPLC-DAD-ESI-LIT-MS and UHPLC-DAD-ESI-QToF-MS. For both caffeic acid esters, UV-vis data, fragmentation patterns, and exact masses revealed the formation of analogous reaction products, supposedly based on a benzacridine core. However, data derived from model systems based on MCA were less complex due to the absence of acyl migration. As expected, presumed N-unsubstituted benzacridines were found with α- but not β-alanine, whereas N-substituted benzacridines were surprisingly found with both. The findings expand current knowledge of benzacridine formation from different precursors and provide a sound basis for the generation of reference substances and studies in real food systems.
More Related Videos
08:06Absolute Quantification of Cell-Free Protein Synthesis Metabolism by Reversed-Phase Liquid Chromatography-Mass Spectrometry
Published on: October 25, 2019
04:3213C6-Glucose Labeling Associated with LC-MS: Identification of Plant Primary Organs in Secondary Metabolite Synthesis
Published on: March 22, 2024
Related Concept Videos
α-Hydroxy Ketones via Reductive Coupling of Esters: Acyloin Condensation Overview
Spectroscopy of Carboxylic Acid Derivatives
In the...
IR and UV–Vis Spectroscopy of Aldehydes and Ketones
Loss of Carboxy Group as CO2: Decarboxylation of Malonic Acid Derivatives
Reactions of Aldehydes and Ketones: Baeyer–Villiger Oxidation
The carbonyl center is activated by...
IR and UV–Vis Spectroscopy of Carboxylic Acids
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency, 1710 cm−1. The C=O bond of the...