Moluccensins R-Y, limonoids from the seeds of a mangrove, Xylocarpus moluccensis

Eight limonoids, named moluccensins R-Y (1, 2, 5-10), and six known compounds, including 6-hydroxymexicanolide (3), were isolated from the seeds of an Indian mangrove, Xylocarpus moluccensis, collected in the estuaries of Andhra Pradesh. The absolute configuration of moluccensin V (7) was confirmed by means of single-crystal X-ray diffraction analysis. The (1)H and (13)C NMR data for 6-hydroxymexicanolide (3) was assigned for the first time, and the 6R absolute configuration established by single-crystal X-ray diffraction analysis. Moluccensin R (1), 6R-hydroxymexicanolide (3), and 2-hydroxyfissinolide (4) exhibited marked antifeedant activity against the third-instar larvae of Brontispa longissima at a concentration of 1 mg/mL. The most potent compound tested was 2-hydroxyfissinolide (4), with an AFC(50) (concentration for 50% antifeedant activity) value of 94 μg/mL at 24 h.