RESUMEN
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.
RESUMEN
To explore the effects of NaF on the growth and cephalotaxine production of Cephalotaxus mannii suspension cells, NaF was added into the C mannii cell suspension cultures at day 15 of culture time. It is documented that NaF suppressed cell growth but enhanced cephalotaxine production. The largest yield obtained of cephalotaxine reached to 9.57mg/L when the cultures were treated with an appropriate dosage of 15mg/L NaF, which was 3.7 times that of the control cultures (2.58mg/L). Additionally, NaF markedly enhanced the activity of glucose 6-phosphate dehydrogenase (G6PDH) and reduced the level of hydrogen peroxide (H2O2) of cells. It was also found that NaF weakened the oxidative damage of cell membrane and led to lower content of malonyl dialdehyde (MDA) in NaF-treated cells compared with the control cells. The MDA content of NaF-treated cells decreased 91% compared to the controls. Although lower membrane lipid peroxidation in NaF-treated cells, its membrane permeability was higher than the control cells and showed a high product secret rate. What is more, NaF boosted the activity of phenylalanine ammonium-lyse (PAL), but did not burst a peak of PAL activity in the time curve of PAL activity. These results indicated NaF acted as an inhibitor of the Enbden Parnas (EMP) pathway, not as an elicitor to promote cephalotaxine production.