Ce. Vaccarini et Gm. Bonetto, Selective phytotoxic activity of withanolides from Iochroma australe to crop and weed species, J CHEM ECOL, 26(9), 2000, pp. 2187-2196
Phytotoxic effects of lochroma australe extract and 4,7,20-oxowithanolides
were examined in Petri dish bioassays at 10, 100, and 1000 ppm. The extract
and the major constituent (17S,20R,22R)-4 beta ,7 beta ,20 alpha -trihydro
xy-1-oxowitha-2,5,24-trienolide (2) reduced growth of the radicle of the we
eds Sorghum halepense (Monoct.) and Chenopodium album (Dicot.). Neither the
extract nor withanolides had significant effect on germination or radicle
length of the commercial crop species Lactuca sativa. From our experimental
data we conclude that the withanolides tested here are natural products wi
th selective herbicidal activity against weed species.