The absolute stereochemistry of protoxylogranatin A - a new protolimonoid from the seeds of Chinese mangrove Xylocarpus granatum

A new protolimonoid, named protoxylogranatin A, has been isolated from the seeds of a Chinese mangrove Xylocarpus granatum. Its structure was elucidated on the basis of modern spectroscopic data. The absolute configuration was determined by the application of the modified Mosher MTPA ester method. The first complete assignments of 1H and 13C NMR spectral data for this protolimonoid were achieved by means of 2D NMR techniques, including 1H-1H COSY, HSQC, HMBC and NOESY spectra.