[Chemical studies on crude drug processing. X. On the constituents of rehmanniae radix (4): comparison of the constituents of various rehmanniae radixes originating in China, Korea, and Japan].

In order to characterize the chemical change of their constituents during the processing of various Rehmanniae Radixes, we have investigated the constituents by comparing with those of Chinese Juku-jio (variously processed root of Chinese Rehmannia sp.), Korean Kan-jio (dried root of Korean Rehmannia sp.) and each two species of Japanese Sho-jio (fresh root), Japanese Kan-jio (dried root), and Japanese Juku-jio (steamed root), prepared from Rehmannia glutinosa Libosch. var. purpurea Makino (Akaya-jio in Japanese) and Rehmannia glutinosa Libosch. forma hueichingensis Hsiao (Kaikei-jio in Japanese). It was found that, during the processing for preparing Kan-jio and Juku-jio from Sho-jio, jio-serebroside (9) and acteoside (10) were provided, and that the iridoid glycosides were completely degradated or their contents decreased remarkably. Quantitative analysis by means of gas liquid chromatography (GLC) has confirmed that the contents of monosaccharides and oligosaccharides in Kan-jio and Juku-jio increased more than those in Sho-jio. During the course of these studies, a new iridoid glycoside named 6'-O-acetylcatalpol (2) was isolated from Japanese Sho-jio and the structure has been determined.