Insecticidal pregnane glycosides from the root barks of periploca sepium

Abstract

To explore novel lead compounds for botanical pesticides from natural sources, a new pregnane glycoside (periplocoside) P2 as well as its isomer, a known pregnane glycoside P1, were isolated from the root barks of Periploca sepium using a bioactivity-guided method, and their structures were confirmed by 1D NMR, 2D NMR, IR, ESI-MSn and HRMS. Their insecticidal activities were evaluated against 3rd instar larvae of M. separata, and the results indicated that P2 exhibited excellent insecticidal activity with LC50 values of 2.9 and 2.2 mg/mL after 24 and 48 h, respectively, much lower than those of the positive control celangulin-V (24.7 and 21.0 mg/mL after 24 and 48 h, respectively). This work demonstrated that pregnane glycosides from Periploca sepium could be promising lead compounds for developing botanical pesticides urgently needed in agriculture.