Capillary-isotachophoretic detection and identification of sennosides A and B in extracts of crude plant drugs.

Abstract

SUMMARYAn analytical system for separating sennosides A and B was established using capillaryisotachophoresis. These are the major purgative components of Rhei Rhyzoma (daiou; the rhyzomes of Rheim palmatum and related species) and Sennae Folium (Senna; the leaves of Cassia angusti florum and related species). Under the conditions employed, the zone of sennoside A was clearly separated from that of its stereoisomer, sennoside B, and the sennosides in the crude drug extracts were identified by mixed charging with authentic samples. The sennoside A and B contents in a total of 30 Rhei Rhyzoma and Sennae Folium specimens were then determined by this system, and a part of them (10 specimens, in total) was also treated by the thin-layer chromatographic method. The results showed that the present capillary-isotachophoresis system is powerful, at least to the same degree as the conventional thinlayer chromatographic system, as a tool for rapid and microscale analysis for use in pharmacognosy. It can be used to measure the major sennoside contents in a large number of crude drug specimens.