Encapsulation of Cynara Cardunculus Guaiane-type Lactones in Fully Organic Nanotubes Enhances Their Phytotoxic Properties

The encapsulation of bioactive natural products has emerged as a relevant tool for modifying the poor physicochemical properties often exhibited by agrochemicals. In this regard, natural guaiane-type sesquiterpene lactones isolated from Cynara cardunculus L. have been encapsulated in a core/shell nanotube@agrochemical system. Monitoring of the F and O signals in marked sesquiterpenes confirmed that the compound is present in the nanotube cavity. These structures were characterized using scanning transmission electron microscopy–X-ray energy-dispersive spectrometry techniques, which revealed the spatial layout relationship and confirmed encapsulation of the sesquiterpene lactone derivative. In addition, biological studies were performed with aguerin B (1), cynaropicrin (2), and grosheimin (3) on the inhibition of germination, roots, and shoots in weeds (Phalaris arundinacea L., Lolium perenne L., and Portulaca oleracea L.). Encapsulation of lactones in nanotubes gives better results than those for the nonencapsulated compounds, thereby reinforcing the application of fully organic nanotubes for the sustainable use of agrochemicals in the future.