HAIRY ROOT CULTURES OF PEGANUM-HARMALA .3. BIOSYNTHESIS OF SEROTONIN AND BETA-CARBOLINE ALKALOIDS IN HAIRY ROOT CULTURES OF PEGANUM-HARMALA

Tryptophan decarboxylase (TDC) activity, and serotonin and harmane alk aloids levels of a Peganum harmala root culture were followed over a g rowth cycle. A close relationship between the peak of TDC activity and the highest specific content of serotonin was found, while such a cor relation was not observed for the beta-carboline alkaloids, the main c onstituents of the root cultures. The content of serotonin, but not of the alkaloids was greatly enhanced by feeding tryptamine. Trials to i dentify individual biosynthetic steps of alkaloid biosynthesis by feed ing were only partially successful, because only the oxidation of dihy dro-beta-carbolines to aromatic harmane alkaloids was observed when th e various alkaloids were added to the root cultures. Tracer experiment s with tryptophan revealed the presence of 5- and 6-hydroxytetrahydron orharmane in the root cultures which, however, should not be biosynthe tic intermediates of the major alkaloids, harmalol and harmine.