Abstract:
To improve the insecticidal activities of avermectin B
2a, the functional carbamate fragment was introduced into the C4" position of avermectin B
2a, and 21 novel avermectin B
2a C4"-carbamate derivatives were designed, synthesized, and their structures were characterized by high-resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR). The insecticidal activity against
Plutella xylostella,
Mythimna separata,
Spodoptera frugiperda,
Ostrinia furnacalis and
Helicoverpa armigera was tested. The results showed that the insecticidal activities of most compounds against
M. separata,
S. frugiperda,
O. furnacalis and
H. armigera were improved to some degrees. Among them, compound
Z5 showed excellent insecticidal activity against
M. separata and
S. frugiperda, with LC
50 values of 1.02 and 2.44 mg/L, respectively. Its insecticidal activity is better than that of the control avermectin B
1a, and more than 20 times higher than that of avermectin B
2a. The structure-activity relationship analysis showed that more lipophilicity of the compound can help to improve the activity of the target compound. Molecular docking studies showed that with the introduction of the functional carbamate fragment into the C4" position of avermectin B
2a, π-π interaction was formed between the benzene ring of the carbamate fragment and the aromatic ring in the receptor protein residue, which was believed to contribute the insecticidal activity of the new compounds.