A straightforward procedure to biosynthesise melatonin using freshly chopped Achillea millefolium L. as reagent

d, l-Tryptophan as the precursor of melatonin and Achillea millefolium L. as the plant cell tissue were used in order to force the plant enzymatic system to enhance the production of melatonin.The biotransformation protocol was performed by adding the precursor to the freshly chopped plant material suspended in water and stirred at room temperature in total darkness. The melatonin content was evaluated by LC-DAD-ESI-MS. The precursor-treated sample gave at least six times (345 ng/g_{fresh plant}) the melatonin amount usually produced in young plants of A. millefolium L. (50 ng/g_fresh plant).The present study shows that, in principle, adding a specific precursor to a suitable freshly chopped plant material can significantly enhance a secondary metabolite production.