Studies on Tannins of Spyrogyra arcta

White amorphous Spyrogyra tannin was prepared from fresh Spyrogyra arcta by the use of acetone. This tannin gave 1 mole of glucose and 5.3 moles of gallic acid when hydrolyzed with tannase. (Table 1). Methyl gallate and gallic acid were detected on the paper chromatogram by methanolysis; then 3, 4, 5-trimethylgallic acid, a small quantity of 4, 5-dimethylgallic acid, and monomethylglucose were obtained by the hydrolysis of the methylated tannin with sulphuric acid. It has, therefore, been proved that Spyrogyra tannin is pentagalloyl-D-glucose similar to Turkish gallotannin, and for example, assumes the chemical structure of I as its main component. It contains moreover, a small quantity of galloylglucose, possesing two or more m-digalloyl groips.