Antifeedant Activity of Spin-Labeled Derivatives of Deoxypodophyllotoxin against Brontispa longissima Larvae

To continue our search for natural product-based compounds for the control of Brontispa longissima larvae, eight spin-labeled podophyllotoxin derivatives (4a-h) and the intermediates 2 and 3 were tested for their insect antifeedant activity against third-instar larvae of B. longissima. Among all the tested compounds, 4a, 4c, 2 and 3 showed pronounced antifeedant activities with AFC50 values of 0.16, 0.31, 0.15 and 0.28 mg/mL, respectively. The different antifeedant activity ranges of these compounds indicated that variation of the structures of L-amino acids in these compounds markedly affected the activity profiles of this compound class, and some important SAR information has been revealed from it.