Identification of alkaloids; the condensation products of biogenic amines with formaldehyde, enzymatically formed from 5-methyltetrahydrofolic acid.

The use of thin-layer chromatography has demonstrated that incubations of indoleamines with 5-methyl[14-C]tetrahydrofolic acid and an enzyme previously described as an N-methyltransferase, do not yield Nw, N1, or O-methylated products. Further elucidation by thin-layer chromatography, gas chromatography, mass spectrometry and selected ion monitoring enabled us to identify the reaction products as tetrahydroisoquinolines and tetrahydro-beta-carbolines in mixtures incubated respectively with catecholamines and indoleamines in the presence of 5-methyl[14-C]tetrahydrofolic acid and enzyme. The alkaloids have been shown to originate from a spontaneous condensation of the corresponding amines with formaldehyde, this latter being formed in the first stage of the reaction by enzymatic conversion from 5-methyltetrahydrofolic acid.