Synthesis, bioactivities and 3D-QSAR of novel avermectin B2a aglycon derivatives

Fourteen avermectin B2a aglycon derivatives were designed and synthesized after removing the oleandrose disaccharide of avermectin B2a. Their structures were characterized by 1H NMR, 13C NMR, HMRS. Preliminary bioassays indicated that these compounds exhibited good insecticidal activity against diamondback moth at 200 mg/L, with mortality no less than 90%. Compounds 10b, 12a, 12c, 17 demonstrated good acaricidal activity against the adult mites, larvae, and good inhibition rate of hatching to mite eggs of Tetranychus cinnabarinus. Compounds 5, 10b, 10c exhibited excellent fungicidal activity against fourteen fungal pathogens in vitro. 3D-QSAR analysis showed that the fungicidal activity of avermectin B2a aglycon derivatives would be increased when a negatively charged and bulky group was introduced at 13-position, which will be instructive for the further modification of avermectin B2a aglycon.