Biosynthesis of tropane ester alkaloids in Datura

Datura meteloides plants were fed via the roots with 1″,2′-¹⁴C]tigloyl hygroline and as a control, 2′-¹⁴C]hygrine. After a week the alkaloids were isolated and degraded. Despite hydrolysis of the putative precursor it was possible, by label ratio, to show that esterification occurs after, and not before, the tropane ring has been synthesized. Hygroline is proposed as a possible intermediate.