Limonoids from Melia azedarach with Deterrent Activity against Insects

The ethanolic extract of ripe fruits of Melia azedarach (Meliaceae) and its subfractions were tested against four insect species, portraying important agricultural pests. Five limonoids were isolated: two tirucallane type triterpenoids never isolated before from this species (21α-methylmelianodiol, 21β-ethylmelianodiol), as well as three ring C-seco limonoids previously reported on this tree (1-O-detigloyl-1-O-cinnamoylohchinolal, 1-O-detigloyl-1-O-benzoylohchinolal and ohchinolal). The complete NMR data of these natural products are reported here. Different patterns of activity were found among the products tested against the different pest models, emphasizing the value of testing potential biocontrol products against different insect targets.