Limonoids with an oxygen bridge between C(1) and C(29) from the seeds of a Krishna mangrove, Xylocarpus granatum.

Ten limonoids, named granatumins L-U (1-10, resp.), were isolated from the seeds of an Indian mangrove, Xylocarpus granatum, collected in the estuary of Krishna, Andhra Pradesh. The structures of these compounds were established on the basis of spectroscopic data. The relative configuration of granatumin L (1) was confirmed by a single-crystal X-ray diffraction analysis. Granatumins L-T (1-9, resp.) belong to the small group of limonoids with an oxygen bridge between C(1) and C(29), while granatumin U (10) is a 28-Me-oxidized mexicanolide. This is the first report of limonoids with an O-bridge between C(1) and C(29) from the Indian X. granatum. The pronounced structural diversity of limonoids from this mangrove might originate from environmental factors.