Studies on Tannins of Spirogyra arcta

Part 4. Formation of Alkyl Gallate from Tannic acid by Fungous Tannase

Abstract

Previously, it was reported that methyl gallate was formed from Spirogyra tannin by the enzymatic action of the spat plasm when Spirogyra arcia was dipped in 70% methyl alcohol. In this experiment, it has been proved that alkyl gallates were also formed from tannic acid by fungous tannase in alcohol solution.
Tannase has been prepared from Asp. niger cultured on the tannic acid-containing medium. When tannase acts on tannic acid in methyl, ethyl, propyl and butyl alcohol solution, corresponding alkyl gallates are formed in proportion to the concentration of alcohols and the maxima of the con-centration of alcohols are as follows; methyl alcohol 50%, ethyl alcohol 40% and propyl alcohol is 30% (Table 1 and Fig. 1, 2). The decomposing-process of tannic acid by tannase in 40% methyl alcohol solution is shown in Fig. 3 and 4.
From the results of these experiments, it is concluded that tannase accelerates the hydrolysis and alcoholysis of depside-type tannin at the same time.