Kinetic study of littorine rearrangement in Datura innoxia hairy roots by (13)C NMR spectroscopy.
The kinetics of tropane alkaloid biosynthesis, particularly the isomerization of littorine into hyoscyamine, were studied by analyzing the kinetics of carbon-13 ((13)C) in metabolites of Datura innoxia hairy root cultures fed with labeled tropoyl moiety precursors. Both littorine and hyoscyamine were the major alkaloids accumulated, while scopolamine was never detected. Feeding root cultures with (RS)-phenyl[1,3-(13)C(2)]lactic acid led to (13)C spin-spin coupling detected on C-1' and C-2' of the hyoscyamine skeleton, which validated the intramolecular rearrangement of littorine into hyoscyamine. Label from phenyl[1-(13)C]alanine or (RS)-phenyl[1,3-(13)C(2)]lactic acid was incorporated at higher levels in littorine than in hyoscyamine. Initially, the apparent hyoscyamine biosynthesized rate (v(app)()hyo = 0.9 micromol (13)C.flask(-1).d(-1)) was lower than littorine formation (v(app)()litto = 1.8 micromol (13)C.flask(-1).d(-1)), suggesting that the isomerization reaction could be rate limiting. The results obtained for the kinetics of littorine biosynthesis were in agreement with the role of this compound as a direct precursor of hyoscyamine biosynthesis.
Laboratoire Androgenèse et Biotechnologie, Laboratoire de Génie Cellulaire, Université de Picardie Jules Verne, 33 Rue Saint Leu, F-80039 Amiens Cedex 01, France.
Arnaud
A
Lanoue
Michèle
M
Boitel-Conti
Jean-Charles
JC
Portais
Jean-Claude
JC
Laberche
Jean-Noël
JN
Barbotin
Philippe
P
Christen
Brigitte
B
Sangwan-Norreel
D000470:Alkaloids / Q000737:chemistry*; D001285:Atropine / Q000737:chemistry; D001286:Atropine Derivatives / Q000737:chemistry*; D002247:Carbon Isotopes / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D046508:Culture Techniques; D013286:Datura stramonium / Q000737:chemistry*; D007700:Kinetics; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D012601:Scopolamine / Q000737:chemistry; D013237:Stereoisomerism; D013997:Time Factors; D014326:Tropanes / Q000737:chemistry*
D000470:Alkaloids; D001286:Atropine Derivatives; D002247:Carbon Isotopes; D014326:Tropanes; C063158:littorine; D001285:Atropine; D012601:Scopolamine