Metabolic pathways of the psychotropic-carboline alkaloids, harmaline and harmine, by liquid chromatography/mass spectrometry and NMR spectroscopy

► Metabolites of harmaline and harmine can be explained by five proposed pathways. ► Three new metabolites of hydroxylated β-carboline-sulphate/-glucuronide were found. ► Harmaline metabolised to harmine by oxidative dehydrogenation was found for the first time. ► Harmaline and harmine mainly excreted in urine and bile as glucuronide and sulphate conjugates. ► Two hydroxylated positions were identified for harmaline and harmine.