Semisynthesis of some matrine ether derivatives as insecticidal agents

In continuation of our program to discover new potential natural-product-based crop protection agents, we synthesized a series of 14-formyl-15-aryloxy/methoxymatrine and 14-aryloxymethylidenylmatrine derivatives as pesticidal agents by structural modification of matrine, a biorenewable quinolizidine alkaloid isolated from Sophora flavescens. The structural assignment was based on spectroscopic and X-ray analysis data. Their pesticidal activities were carried out against two typically crop-threatening agricultural insect pests, Mythimna separata Walker and Plutella xylostella Linnaeus. Compounds 4i and 4k exhibited more potent oral toxicity than matrine against 3rd-instar larvae of P. xylostella. As compared with matrine, all derivatives displayed a growth inhibitory property against early 3rd-instar larvae of M. separata, and in particular compounds 4i-k displayed more promising insecticidal activity than toosendanin. Some interesting results of structure-activity relationships were also observed.