Insecticidal Alkaloids from the Seeds of Macleaya cordata on Cotton Aphid (Aphis gossypii)

摘要

Alcohol extracts from the seeds of Macleaya cordata have shown a significant insecticidal effect against the growth of the cotton aphid, Aphis gossypii Glover. In this study, we aimed to isolate the principal component of M cordata to manifest its insecticidal effect on A. gossypii. The dried seeds of M cordata were extracted with 80% aqueous methanol (MeOH), and the concentrated extracts were partitioned successively with ethyl acetate (EtOAc), n-butyl alcohol (n-BuOH), and H2O. During the search for an insecticidal compound against the aphids, activity-guided fractionation led to the isolation of two alkaloids from an n-BuOH fraction through repeated silica gel column chromatographic separations. Based on NMR, MS, and IR. spectroscopic data, the chemical structures of the compounds were determined to be 8-hydroxydihydrochelerythrine (1) and 8-methoxydihydrosanguinarine (2) This is the first study in which 8-methoxydihydrosanguinarine was isolated from M cordata. 8-Hydroxydihydrochelerythrine (1) and 8-methoxydihydrosanguinarine (2) decreased the survival of the cotton aphid by 76.1 +/- 7.9 and 73.6 +/- 14.6% at 100 ppm, respectively,