Glucosylation of isatin-3-oxime followed by 2D in situ NMR in plant cells at highest magnetic field without labelling

In vivo monitoring of alkaloid metabolism in hybrid plant cell cultures by 2D cryo-NMR without labelling

Non-invasive measurements of alkaloid metabolism in plant cell suspension cultures of a somatic hybrid from Rauvolfia serpentina Benth. ex Kurz and Rhazya stricta Decaisne were carried out. When cell samples were taken sequentially from a stock feeding experiment, measuring times for in vivo NMR of 40 min were sufficient for following conversions of alkaloids at the natural abundance of 13C. Degradation of ajmaline added to the cells at 1.6 mM concentration to raumacline could be monitored after 96 h on a standard 800 MHz NMR instrument (Avance 800). Feeding vinorine an intermediate of ajmaline biosynthesis at 1.8 mM showed with a 500 MHz CryoProbe that the alkaloid enters two metabolic routes. Vinorine is intracellularly transformed on route I through vellosimine and 10-deoxysarpagine into sarpagine. On route II, the alkaloid is converted by hydroxylation through vomilenine into the glucoside raucaffricine. Intracellular alkaloid concentrations of approximately 500 microM are measurable in vivo with cryogenic NMR technology.