Galloyl Derivatives and Tannins

Penta-O-galloyl- or penta-0-digalloyl-D-glucose (galloyltannins) 

Fischer, Ber. 52, 809 (1919) K. Freudenberg, Tannin, Cellulose and Lignin. Springer, Berlin, 1933. 

Glucogallin obtained from the Chinese rhubarb by Gilson has been identified (100) through synthesis as l-0-galloyl-j3-D-glucose. 

The bark of the North American shrub Hamamelis virginica contains in addition to other tannins, about 1 to 2% of crystalline hamameli-tannin (XVI) 97). The substance has the composition of a di-O-galloylhexose, and on acid or enzyme hydrolysis, it gives two moles of gallic acid and one mole of an unusual hexose, hamamelose (XVII), whose structure has been established as 2-C-(hydroxymethyl)-D-ribose (XVII) 101). 

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