Glucopyranosyloxybenzyl derivatives of (R)-2-benzylmalic acid and (R)-eucomic acid, and an aromatic glucoside from the pseudobulbs of Grammatophyllum speciosum

Three new glucosyloxybenzyl derivatives of (R)-2-benzylmalic acid and of (R)-eucomic acid, grammatophyllosides A-C, and a new phenolic glucoside, grammatophylloside D, were isolated from the pseudobulbs of Grammatophyllum speciosum along with cronupapine, vandateroside II, gastodin, vanilloloside, orcinol glucoside, and isovitexin. The structure elucidations of these compounds were based on analyses of physical and spectroscopic data, as well as chemical evidence.