1954 年 74 巻 12 号 p. 1357-1362
It had been found that the relation Y=39.6-43X holds for the Rb value (X) and tannic acid content (Y) of the leaves of Geranium nepalense. Based on these finding, Rb values of the plants collected throughout Japan during July and August were studied and following points were clarified.
1) Rb values are generally 0.29-0.56 and from the above equation, the tannin content is calculated as 27-16%.
2) Mean values of plants collected during July were approximately equal to those in August.
3) Rb values of plants bearing white flowers were smaller than those of red flowers while average values from the same species collected during July were approximately equal to those in August.
4) Taking the Rb value of the products meeting pharmacopoeial standards as below 0.45, or taking 0.47 by considering experimental errors, 79% of 107 samples were found to meet this standard. If the tannic acid content is taken as over 20%, Rb value will become 0.46, and 73% meets the standard.
Summarizing the series of studies reported in Parts I to V of this series, following new method of examination is proposed.
Leaves are plucked uniformly from the sample, dried at 80° for 30 minutes, and reduced to a pharmacopoeial coarse powder. To 40cc. of boiling distilled water, 0.4g. of this coarse powder is added, and refluxed for 30 minutes, under brisk boiling. This is cooled to the room temperature, 5cc. of the supernatant is added to 15cc. of distilled water, and this solution is divided into four portions. To each portion, molar eqivalent of sodium hydroxide is added, extemporaneously, 5cc. of 0.2% aqueous solution of methylene blue is mixed in with agitation, and this mixture is transferred equally to eight glass cylinders of 3cm. internal diameter and height. Two standards of 5cc. of the foregoing 0.1% methylene blue solution in identical glass cyclinder are placed in the middle, with the sample solutions on the either side, and the capillary image is developed by suspending strips of filter paper (Toyo Roshi No. 50, 2×30cm.), dipping the end in each cylinder. The average height (cm.) of methylene blue in the mixture is designated as B, that of the standard as A, and the ratio of B to A, B/A, must be less than 0.46.