ABSTRACT
Objective: To investigate the effects of L-tryptophan and its derivative 5-methyl-DL-tryptophan (5-MT) on suspension cells growth and cephalotaxine production of Cephalotaxu mannii. Methods: The cell suspension cultures were treated with L-tryptophan and 5-MT on day 15, respectively. Then the cell growth, cephalotaxine production, and activity of key enzymes in the metabolism pathway were determined. Results: L-tryptophan and 5-MT could enhance cephalotaxine production. The cultures treated with 5 mg/L L-tryptophan showed the highest cephalotaxine yield (2.944 mg/L). While treated with 10 mg/L L-tryptophan and 5 mg/L 5-MT, the cephalotaxine yields were 1.947 and 2.192 times of the control culture (1.343 mg/L); The biomass of suspension cultures were decreased by 9.35% and 18.04%, respectively, less than those in the control group (2.406 g/L); The activity of 3-deoxy-D-arabino- heptulosonate-7-phosphate synthase was decreased by 12.4% and 5.57% compared with the control (0.67 U/mg); The activity of phenylalanine ammonium-lyase activity increased by 37.72% and 28.02% and the total phenolics content increased by 19.14% and 9.61% compared with the control (78.21 U/mg and 0.36 mg/mL). Conclusion: L-tryptophan and its derivative 5-MT can inhibit the L-tryptophan biosynthetic pathway and promote the accumulation of cephalotaxus alkaloids.