Isotopic labelling-based analysis elucidates biosynthesis pathways in Saccharomyces cerevisiae for Melatonin, Serotonin and Hydroxytyrosol formation

•Bioactive compounds are produced during alcoholic fermentation.•Yeasts can synthetize melatonin by different pathways: from tryptophan and serotonin.•Yeasts produce Hydroxytyrosol from labelled tyrosine and also from other sources.•Isotopic labelling proved useful as strategy to elucidate biosynthetic pathways.