Validation of an Analytical Method to Determine Melatonin and Compounds Related to l-Tryptophan Metabolism Using UHPLC/HRMS

Abstract

Melatonin is a bioactive compound that is present in wines because of the metabolism of l-tryptophan by yeasts. Even though the complete pathway of synthesis is not well elucidated, certain related indolic compounds might be involved in it. Consequently, their determination is a matter of interest. On one hand, their formation during fermentation might be related to a specific role for yeasts metabolism, not known so far. On the other hand, the synthesis by yeasts of bioactive compounds with putative health benefits for consumers, such as melatonin or serotonin, is a relevant matter. This paper aims to develop and validate an analytical method by ultra high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC/HRMS) to monitor both melatonin and related indolic compounds, in order to decrease their detection limits and make it possible to assess their occurrence in culture medium and fermented products. In addition, the other objective is to evaluate the production of these compounds by a commercial Saccharomyces cerevisiae used to make white wines. Diminishing the limit of detection below 0.5 ng mL−1 for all compounds under study is an achievement of this work. Furthermore, the strain under study (AROMA WHITE) has been found to synthesise melatonin and related compounds as serotonin. Additionally, the evolution of these compounds over time may contribute to understanding the role that they play in yeast metabolism.