[Effects of nitrogen forms on camptothecin content and its metabolism-related enzymes activities in Camptotheca acuminata seedlings].
OBJECTIVE
To investigate the effects of nitrogen forms on the camptothecin (CPT) content, tryptophan synthase (TSB) and tryptophan decarboxylase (TDC) activities in Camptotheca acuminata seedlings.


METHODS
The seedlings of C. acuminata with 6 pairs of leaves were subjected to 5 different NH4(+) -N/NO3(-) -N ratio (0 : 100, 75 : 25, 50 : 50, 25 : 75, 100 : 0) treatments by sand culture in a greenhouse. The CPT content, TSB activity in the young leaves and TDC in the stem barks of the seedlings were determined by HPLC on the 15th, 30th, 45th, 60th and 75th day, respectively.


RESULTS
The obvious relationship between CPT content and nitrogen forms was observed. When NH4(+) - N /NO3(-) -N ratio was 25 : 75, CPT accumulation in young leaves displayed the best advantages (the highest value is 5.69 per thousand) and increased in the early 30 days of treatment and then declined. There was no obvious relationship between TSB activity in the young leaves and nitrogen forms. TDC activity in the stem bark was the highest when NH4(+) -N /NO3(-) -N ratio was 25 : 75, and the change of TDC activity paralleled to CPT content in the young leaves.


CONCLUSIONS
A short-term treatment that NH4(+) -N /NO3(-) -N ratio was 25:75 may gain high CPT content in the young leaves through enhancing the TDC activity in the stem bark of C. acuminata seedlings.
Sun
Shi-Qin
SQ
Harbin Medical University, Daqing Branch, Department of Pharmacy, Daqing 163319, China.
Yan
Xiu-Feng
XF
D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000378:metabolism; D029769:Camptotheca / Q000187:drug effects* / Q000201:enzymology* / Q000378:metabolism; D002166:Camptothecin / Q000378:metabolism*; D004365:Drugs, Chinese Herbal / Q000378:metabolism; D009584:Nitrogen / Q000737:chemistry* / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects* / Q000201:enzymology* / Q000378:metabolism; D014367:Tryptophan Synthase / Q000378:metabolism
D004365:Drugs, Chinese Herbal; D001142:Aromatic-L-Amino-Acid Decarboxylases; D014367:Tryptophan Synthase; D009584:Nitrogen; D002166:Camptothecin