DYNAMICS OF THE BIOSYNTHESIS OF METHYLURSUBIN IN PLANT-CELLS EMPLOYING IN-VIVO C-13 NMR WITHOUT LABELING

In vivo NMR experiments with a digital 600 MHz instrument, exploiting the natural abundance of C-13, allowed us for the first time to follow the biosynthesis of the newly detected glycoside, methylursubin (4-methoxyphenyl-O -beta-D-primeveroside), from 4-methoxyphenol through the intermediate methylarbutin in cell suspensions of the Indian medical plant, Rauwolfia serpentina. The metabolic dynamics indicate that, within 48 hr, 4-methoxyphenol is almost completely converted into the primeveroside, methylursubin. Because of the higher sensitivity at 150.9 MHz compared to that at 100.6 MHz, measuring times could be reduced to 1.5 hr. This allows detailed monitoring of the conversion of 4-methoxyphenol with an excellent signal-to-noise ratio.