Phenolic compounds from Coix lachryma-jobi var. Ma-yuen

Four phenolic compounds and adenosine were isolated from the roots of Coix lachryma-jobi var. ma-yuen. On the basis of spectral evidence and the results of chemical synthesis, the structures of three were determined to be 4-ketopinoresinol, and threo- and erythro-1-C-syringylglycerol. The aglycone moiety of a new glucoside, 2,6-dimethoxy-p-hydroquinone 1-O-β-d-glucopyranoside, was determined from 13C and 1H NMR spectra and the position of the O-glucosyl moiety was confirmed by single-crystal X-ray analysis.