Ptaquiloside, the major carcinogen of bracken fern (Pteridium aquilinu
m), was isolated in high yield from milled freeze-dried plant material
. Because the compound is unstable, a new method was devised to avoid
steps which caused loss of activity. Modern multipulse and 2D NMR tech
niques allowed confirmation of the previously proposed structure, alth
ough some assignments were shown to be incorrect.