Natural products-based insecticidal agents 6. Design, semisynthesis, and insecticidal activity of novel monomethyl phthalate derivatives of podophyllotoxin against Mythimna separata Walker in vivo.

To discover the more potent analogs, 12 novel monomethyl phthalate derivatives of podophyllotoxin were synthesized and preliminarily tested against the pre-third-instar larvae of Mythimna separata Walker in vivo at the concentration of 1mg/mL. Compounds 8e-i showed the higher insecticidal activity than podophyllotoxin. Especially 8g exhibited the most potent insecticidal activity compared with toosendanin, a commercially available insecticide derived from Melia azedarach. The structure-activity relationships demonstrated that trans-lactone, 4beta-substitution, 2beta-chlorine substitution, and 4'-methoxy group were the important structural properties of podophyllotoxins for good insecticidal activity. Copyright 2010 Elsevier Ltd. All rights reserved.