Detection of Senna and Rhubarb Used Only as Drugs from Herbal Teas Advertising Effect of Weight Reduction

Abstract

Senna leaf, senna pod and rhubarb are the strong laxative crude drugs peculiarly containing such effective components as sennoside A (SA) and sennoside B (SB). These crude drugs are prescribed as ingredients used only as drugs by the notification of Pharmaceutical Affairs Bureau. Therefore, foods containing these drugs are regulated as illegal drugs, unapproved/unpermitted drugs, on the Pharmaceutical Affairs Law. We had successfully identified and detected rhubarb besides senna leaf and senna pod from some of imported herbal teas which were regarded as "health foods."The established method for the identification of these drugs is as follows. As the accurate method for the detection of characteristic common components of SA and SB three dimensional-HPLC (3D-HPLC) and TLC were utilized and they were distinguished each other based on the peculiarities shown below. 1. Rhein 8-glucoside is a characteristic component of rhubarb and successfully detected by 3D-HPLC. 2. On the TLC chromatogram for the identification method of senna or rhubarb described in Japanese Pharmacopoeia (JP), each unique spot could be found, a pale white spot at senna, a remarkable orange-yellow spot usually observed on a mixture of free anthraquinones, chrysophanol, emodin, aloeemodin, etc. at rhubarb. 3. Through magnifying glass, even from cut samples, each characteristic tissue is found, namely pieces of leaves with an entire, acuminate, asymmetric leaf base, swelling veins or some hairs on the senna leaf, glossy pieces of pod changed to dark in place and often retuse seeds on senna pod, and brownish porous pieces of rhubarb. 4. Under a microscope, warty hairs from senna leaves and large clustered crystals (over 50μm) with vessels, pigments and other components from rhubarbs could be respectively observed as described in JP.