Insecticidal flavaglines and other compounds from Fijian Aglaia species

Bioassays with lipophilic crude extracts of four Fijian Aglaia species against Spodoptera littoralis displayed strong insecticidal activity for A. basiphylla and A. gracilis, whereas A. archboldiana and A. vitiensis did not have any significant effects. The insect toxicity of A. basiphylla was caused by the well known benzofuran flavaglines rocaglamide, desmethylrocaglamide and aglafoline. In contrast, A. gracilis contained four related pyrimidinone derivatives in the root and stem bark, including two new congeners named marikarin and 3'-hydroxymarikarin. Moreover, two new putrescine bisamides, secoodorine and secopiriferine, a new benzopyran flavagline. desacetylaglain A. and a new norsesquiterpene were isolated from the leaves together with three known bisamides and 3-hydroxy-5,7,4'-trimethoxyflavone. The structures of the new compounds were elucidated by spectroscopic methods. Comparative feeding assays within the active pyrimidinone flavaglines showed that the free hydroxy group in aromatic ring A of marikarin diminishes insecticidal activity.