Novel antifeeding limonoids from Dysoxylum hainanense

Seven novel limonoids were isolated from the bark of Dysoxylum hainanense Merr, of which four were limonoid acids {dysoxylumic acids A (), B (), C (), D ()}, and three others {dysoxylumolides A (), B (), C ()}. Their structures were established by extensive NMR experiments. In compounds ()–(), C-16 was an oxymethine group, which is rare in limonoids. Dysoxylumic acids A–C as well as known compounds dysoxylumins A–C exhibited significant antifeeding activity against Pieris rapae L, while dysoxylumolides A–C and dysoxylumic acid D showed moderate activity.