Rhei Rhizoma (rhubarb), called Daio in Japanese, is one of the important herbal drugs. To date, qualitative analysis of its typical laxative components, anthraquinone derivatives including sennoside A, has been used for the qualitative evaluation of rhubarb by means of several analytical methods.
1)However, such evaluation is incomplete because rhubarb has been used for the treatment of "Oketsu" (various syndromes caused by the obstruction of blood circulation such as dysmenorrhoea, hypermenorrhea, hematemesis, lower abdominal pain, etc.), jaundice, diarrhea and food poisoning, in addition to constipation. Although various individual pharmacological effects related to the above treatments, such as purgative activity, 2,3) anti-bacterial and anti-fungal activities, 4) anti-tumor activity, 5) anti-inflammatory and analgesic activities, 6,7) improvement of renal disorders, [8][9][10][11] improvement of nitrogen metabolism, 12,13) psychotropic activity, 14) anti-allergic effects, 15,16) anti-cholera toxin activity, 17,18) promoting blood circulation and removing blood stasis, 19) and the various involved active compounds have been reported, comprehensive chemical study of the composition of bioactive constituents of rhubarb has been rare. Kashiwada et al. 20) set up a HPLC method to analyze almost all the phenolic compounds simultaneously, and reported that the majority of the compounds could be separated by a 0.05 M H 3 PO 4 solution-acetonitrile gradient elution system. However, several compounds, i.e. procyanidin B-1 3-Ogallate and 1,2,6-trishowed overlapping peaks. In addition, polymeric procyanidins, i.e. RG-tannin and rhatannin, showed serious band broadening and tailing. Therefore, it is still necessary to develop a HPLC method which can be used for the effective separation and quantitative determination of the active components, which would then be used to evaluate the quality of rhubarb samples.In this study, we developed new HPLC methods to analyze 30 compounds (1-30, Fig. 1) in rhubarb, quantitatively, and the contents of the active components were compared in rhubarb samples of different botanical origins.
ExperimentalMaterials Three Rhei Rhizoma samples derived from the following species were quantitatively examined: rhizomes of R. tanguticum (Huangnan County, Qinghai Prov., TMPW no. 20065), R. palmatum (Jiulong County, Sichuan Prov., TMPW no. 20216) and R. officinale (Wanyuan County, Sichuan Prov., TMPW no. 20267). The botanical origins of each sample were correctly identified by the molecular biological methods previously reported. 21,22) The rhubarb sample (Qinghai Prov., TMPW no. 19929) used for the isolation of standard compounds was purchased from Uchida Wakanyaku Co., Ltd. (Japan). Voucher specimens have been deposited in the Museum of Materia Medica, Institute of Natural Medicine, University of Toyama (TMPW).Chemicals and Reagents Sephadex LH-20 (Amersham Biosciences, Sweden) and reversed phase gel MCI CHP-20P (70-150 mesh, Mitsubishi Chemical Co., Japan) were used for column chromatography. A...
