ISOTENTOXIN, A CONVERSION PRODUCT OF THE PHYTOTOXIN TENTOXIN

Isotentoxin, the E-isomer of the phytotoxin tentoxin, can be produced from tentoxin by UV irradiation. A clean separation of both cyclopepti des is possible using adsorption chromatography on Sephadex G-15. Sinc e artificial daylight causes an inter-conversion of both compounds, sp ecial care should be taken in consideration for the interpretation of the chlorosis bioassays. Indeed, isotentoxin seems to have no chlorosi s activity, but has stronger wilting effects than tentoxin against the problem weed Galium aparine L.