Simultaneous Determination of Anthraquinones, Their 8-.BETA.-D-Glucosides, and Sennosides of Rhei Rhizoma by Capillary Electrophoresis

Abstract

In a continuation of our work on quinones that occur widely in the plant kingdom and that may have biological activities, we have developed a simple cyclodextrin modified capillary zone electrophoresis (CD-CZE) to separate and determine emodin, chrysophanol, aloe-emodin, rhein, emodin-8-b-D-glucoside, chrysophanol-8-b-D-glucoside, rhein-8-b-Dglucoside, sennoside A, and sennoside B of Rhei Rhizoma. Rhei Rhizoma is an old-and well-known herbal medicine known for its purgative effect due to anthracene derivatives, especially their glycosides. The analysis of these compounds and anthraquinones in pharmaceutical preparations or in complex matrices such as crude plant extracts is, therefore, of special interest.1,2) Some naturally-occurring anthraquinones have already been examined by thin layer chromatography, 3) HPLC methods, [4][5][6][7][8] and capillary electrophoresis (CE), [9][10][11][12][13][14] however, only a single component or limited components have been determined in the majority of them. A few simultaneous analyses of different types of components have been conducted. 6,8,14) Studies related to simultaneous determination by CE are especially rare. Rhei Rhizoma contains a wide variety of components, including monomeric anthraquinones, their glycosides, and dimeric anthrone glycosides, and thus simultaneous determination of these different groups of components showing large differences in polarity is desirable for the quality control of the herb. For this purpose, we have developed a simple and rapid CD-CZE method (except for rhein) using 0.005 M a-CD in 0.03 M borate buffer (pH 10.0) containing 20% acetonitrile. ExperimentalReagents and Materials Sodium tetraborate, sodium dodecyl sulphate (SDS), sodium hydroxide, hydroxypropyl-b-CD (HP-b-CD), g-CD, and HPg-CD were purchased from Wako Pure Chemicals (Osaka, Japan), a-CD, b-CD, and sennoside A (8) from Nacalai Tesque (Kyoto, Japan), sennoside B (9) from Funakoshi (Tokyo, Japan), and boric acid from Fluka (Buchs, Switzerland). Acetonitrile, methanol, and water were of HPLC grade. Emodin (1) and chrysophanol (2) were isolated from the root bark of Cassia siamea.15) Emodin-8-b-D-glucoside (5) was isolated from the root of Polygonum cuspidatum SIEB. et ZUCC. 16,17) and chrysophanol-8-b-D-glucoside (6) from Cascara Sagrada (the root of Rhamnus purshiana DC.).18,19) Aloeemodin (3), rhein (4), and rhein-8-b-D-glucoside (7) were isolated from Rhei Rhizoma 20) (Fig. 1). Rhei Rhizoma (Rheum palmatum L., Rheum tanguticum MAXIM.) was purchased from The Iguchi Pharmacy (Kobe, Japan).Procedure for CE The CE analyses were carried out using a Beckman MDQ and P/ACE System 5000 apparatus (Fullerton, CA, U.S.A.) equipped with a UV detector set at 254 nm, a diode array detector, and a Beckman untreated fused-silica capillary (570 mmϫ75 mm i.d.; 500 mm effective length). The analytical conditions were as follows: sampling time, 5 s (hydrodynamic mode; 0.5 p.s.i.); applied constant voltage, 20 kV; column temperature, 20°C. The CD-CZE electrolyte was a buffer solution prepared b...

Analysis of phenolic compounds in rhubarbs using liquid chromatography coupled with electrospray ionization mass spectrometry

“…Therefore, a simple, rapid, and accurate method for the analysis of bioactive compounds in rhubarb is necessary for the quality control of crude rhubarb drugs and their pharmaceutical preparations. Qualitative and quantitative analyses of rhubarbs have been extensively pursued [11][12][13][14]. However, most of these investigations focus on the determination of anthraquinones by TLC, HPLC, and HPCE.…”

Characterization of emodin metabolites in Raji cells by LC–APCI-MS/MS

“…These results proved that the method for the measurement of emodin metabolites was reliable and reproducible. The detection limit of emodin for HPLC, capillary electrophoresis (CE), and the present LC-APCI-MS/MS method were 40 ng/mL, 44 100 ng/mL, 45 and 13.5 pg/mL, respectively. Thus, the sensitivity of LC-MS/MS analysis was superior to that of HPLC and CE.…”

High-Performance Liquid Chromatographic Determination and Metabolic Study of Sennoside A in Daiokanzoto by Mouse Intestinal Bacteria

“…HPLC methods for the determination of sennoside A in rhubarb have been developed. [11][12][13][14] However, these methods were not applicable to the determination of sennoside A in incubation mixtures of DKT, because metabolites derived from glycyrrhiza constituents interfered with the measurement of sennoside A. We have reported an HPLC method for determination of sennoside A in Kampo medicines containing rhubarb 18) ; however, it is difficult to measure sennoside A in incubation mixtures of DKT because sennoside A cannot be separated from other metabolites.…”

“…Although we developed an HPLC method for simultaneous determination of sennoside A metabolites in studies on the metabolism of sennoside A with rat and mouse feces, 10) rheinanthrone was unstable in the incubation mixtures of rhubarb. Therefore, sennoside A was used as a marker compound in this study on the metabolism of sennoside A. HPLC methods for the determination of sennoside A in rhubarb have been reported, [11][12][13][14] but these methods were not applicable to the determination of sennoside A in the incubation mixtures of DKT because of interferences from the other metabolites present.…”