Farmers of the Franca region in Brazil observed that Bidens sulphurea was able to eliminate the Panicum maximum weed that infected the coffee plantations, without affecting the crop. To determine if the ability of inhibition observed can be due to the presence of phytotoxic compounds from leaves and roots, a biodirected isolation and spectroscopic characterization have been realized. The leaf dichloromethane and root acetone extracts were the most active, and the former appeared to be more phytotoxic to the target species, including four weeds. Twenty-six compounds were isolated from leaves and roots, and four of them have been described for the first time.

The major compounds in the leaf extract are the sesquiterpene lactones that showed a marked inhibition. A. viridis and P. maximum were the most sensitive species among weeds tested. These phytotoxic lactones were also evaluated on A. viridis and P. maximum in hydroponic conditions, with A. viridis being the species most affected by lactones. This is the first time that sesquiterpene lactone phytotoxicity has been evaluated in hydroponic culture. This is a preliminary approach of the use of B. sulphurea for weed control in agriculture, both as cover crop or using its components as natural herbicide leads.