Phytotoxic polyacetylenes from roots of Russian knapweed (Acroptilon repens (L.) DC.)

Acroptilon repens represents one of the most threatened invasive weeds of North America. The bioassay-guided fractionation of this species yielded five acetylenic compounds; one hitherto unknown. The presence of these compounds in the exudates and the soil surrounding the plant was also investigated. Contrary to previous reports, the root exudates did not contain 7,8-benzoflavone.