ゲンノショウコ試験法研究 (第4報)

ゲンノショウコ葉体のタンニン酸含量の季節による移動について

抄録

There is no test rules for the determination of tannic acid in the Pharmacopoeia for Geranium (dried whole herb of Geranium nepalense) although tannic acid is assumed to be one of its effective principles. The experimental results revealed that there is a functional relationship between the Rb value and tannic acid content of Geranium (leaf blade) and that tannic acid content determined with methylene blue could be taken as the actual content of tannic acid. Based on these findings, seasonal variation of tannic acid content in the leaf blade of Geranium was examined in order to offer these data for Pharmacopoeia tests. The content of tannic acid was found to be the smallest during December to February in the same stock of plants growing in the same area, to increase gradually, and become the maximum during June to August, decreasing thereafter. By plotting this on a graph, a curve is obtained and with the measurement of the Rb value it would make it possible to detect the content of tannic acid (quality) of the plant, knowing the time of collection.