海人草有効成分の比色定量法 (第1報)

抄録

The coloration of digenic acid, the effective principle of Digenea simplex, with ninhydrin differs in acid and alkaline reaction. In acid solution, the dye produced transits to the organic solvent layer, and that in the isobutyl alcohol solution shows absorption maximum at 410mμ, the color fading by light. In the case of alkaline solution, the production of the dye increases by the addition of a reductive agent, such as ascorbic acid, besides ninhydrin. The colored solution exhibits the absorption maximum at 425mμ. Both reactions can be utilized for the colorimetric determination of digenic acid. After warming at 70° the solution of digenic acid with ninhydrin at pH 4, the dye is transited to the isobutyl alcohol layer, or the acid is heated in aqueous pyridine solution or in a buffer of pH 8.5, with the addition of a small amount of ascorbic acid, for 15 minutes at 100°, the red color of reduced ninhydrin is discolored by air oxidation, and the resultant solution is submitted to colorimetry. The optimal determination range is 10-50 γ in acid reaction, and 30-150γ in alkaline reaction. With Digenea extract, digenic acid is isolated by paper partition chromatography and colorimetrically determined. The content of digenic acid in Digenea simplex Ag. is usually around 450-500mg. per kg.