Selective Extraction of Bioactive Phenylethanoids from .

Cardenolide-free extracts from showed significant antifeedant effects against the aphid and this activity correlated with their phenylethanoid content. The content in phenylethanoids of has been studied. Maceration of the aerial parts of was used for the selective extraction of the natural compound rengyolone () and the aglycone of cornoside (compound ). Pure rengyolone () can be obtained from in approximately 90% purity from fresh plant from the CHCl soluble fraction of the ethanolic extract (0.8% yield). The ethanol extraction of freshly collected showed the presence of compound as the only phenylethanoid. Compound was proven to easily evolve to rengyolone. Due to this instability, and although its presence in plants has been previously reported, the spectroscopical data of are reported herein for the first time. Selective mono-acetylation of compound of led to the active natural compound hallerone (). The aphid antifeedant (against ) and nematicidal (against root-knot nematode ) activities of these compounds have been evaluated. Here we report for the first time on the aphid antifeedant effects of , , and . Additionally, the nematicidal activity of hallerone () is described here for the first time.