The root bark of Melia toosendan afforded four new limonoids with a C-19/C-29 bridged acetal structure, together with two known limonoids, 12α-hydroxyamoorastatone and its 12-acetate. The new compounds were elucidated as 1-O-acetyltrichilin H and 29-O-substituted amoorastatone derivatives, named neoazedarachins A, B and D, by spectroscopic and chemical means. Their antifeedant activity was also studied.
Keywords: 1-O-acetyltrichilin H; Melia toosendan; antifeedant; limonoid; neoazedarachins.