Acaricidal Activity of Bufadienolides Isolated from Drimia pancration against Tetranychus urticae, and Structural Elucidation of Arenobufagin-3-O-α-L-rhamnopyranoside

Chemical characterization of the bulbs of Drimia pancration was conducted to isolate four steroidal saponins (1–4). Earlier, we focused on the structural elucidation of compounds 1–3. Herein, by means of 1H-NMR, 13C-NMR, Nuclear Overhauser Effects (NOE), and 2D-NMR spectra, the full stereochemical structure of 4 is reported, and all the 1H and 13C signals are assigned. Compounds 1–4 were tested for their acaricidal properties against the two-spotted spider mite Tetranychus urticae. Our results showed excellent activity of compound 1, with an LD50 (µg/cm2) of 0.29 and a LD90 (µg/cm2) of 0.96, whereas compounds 2, 3, and 4 showed moderate activity. Furthermore, t…