Biosynthesis of gallotannins. Enzymatic conversion of 1,6-digalloylglucose to 1,2,6-trigalloylglucose.

Cell-free extracts from Rhus typhina L. (staghorn sumach) leaves were found to catalyze the transfer of the galloyl moiety of β-glucogallin (1-O-galloyl-β-D-glucose) to 1,6-di-O-galloyl-β-D-glucose, resulting in the specific formation of 1,2,6-tri-O-galloyl-β-D-glucose, an intermediate of gallotannin biosynthesis. The reaction product was unequivocally identified by co-chromatography with authentic references using reversed-phase high-performance liquid chromatography and by (1)H-nuclear-magnetic-resonance spectroscopy.