Protoxylogranatin B, a Key Biosynthetic Intermediate from Xylocarpus granatum: Suggesting an Oxidative Cleavage Biogenetic Pathway to Limonoid

Protoxylogranatin B, a new protolimonoid identified from the seeds of a Chinese mangrove, Xylocarpus granatum, was proposed as the key biosynthetic intermediate.Its structure was established on the basis of spectroscopic techniques, including 1 H-1 H COSY, HSQC, HMBC and NOESY spectra.The finding of this compound suggested an oxidative cleavage biogenetic pathway from protolimonoid to limonoid.