A Simple Method to Identify the Unprocessed Strychnos Seeds used in Herbal Medicinal Products

Abstract

The seeds of Strychnos nux-vomica are popularly used in the treatment of arthritis. Being extremely toxic, the raw seeds are forbidden and must be processed before clinical use. The quality of crude and processed Strychnos seeds can be controlled by examining the toxic alkaloids using established HPLC methods. But this procedure does not work in the case where the seeds are powdered and mixed with other medicinal materials in proprietary production. In this quality control study on Strychnos seeds, the contents of two major toxic alkaloids (strychnine and brucine) and a major non-alkaloid constituent (loganic acid) in twenty-four samples of Strychnos seeds (nine processed and fifteen unprocessed) were compared using published HPLC-UV methods. The results showed that the better the seeds were processed, the less loganic acid was found. The alkaloids and non-alkaloid components simultaneously decreased in processed seeds. The content ratio between alkaloids and loganic acid was clearly different in well-processed and crude Strychnos seeds. Based on this interesting discovery, a simple chromatographic method was established which allows a simultaneous determination of loganic acid and the alkaloids strychnine and brucine. The relative peak area (RPA) of strychnine-to-loganic acid was revealed to be a reliable key quality control parameter in order to effectively identify the processed seeds. This new method has been successfully applied to detect the insufficiently processed Strychnos material in marketed herbal medicinal products.

Strychnos nux-vomica - Loganiaceae - strychnine - loganic acid - relative peak area

References

• 1 Bensky D, Gamble A. Chinese herbal medicine. Seattle; Eastland Press 1986: 646
• 2 The Pharmacopoeia Committee of China. The monograph Semen Strychni of the Chinese Pharmacopoeia (English edition, Vol. I). Beijing; the People's Medical Publishing House 2005: 303
• 3 Cai B C, Wu H, Yang X W, Hattori M, Nainba T. Analysis of spectral data for ¹³C NMR of sixteen Strychnos alkaloids.  Acta Pharm Sin. 1994;  29 44-8
• 4 Baser K HC, Bisset N G. Alkaloids of Srilankan Strychnos nux-vomica. .  Phytochemistry. 1982;  21 1423-9
• 5 Samulesson G. Drugs of natural origin. Stockholm; Swedish Pharmaceutical Press 1992: 282
• 6 Choi Y H, Sohn Y M, Kim C Y, Oh K Y, Kim J. Analysis of strychnine from detoxified Strychnos nux-vomica seeds using liquid chromatography-electrospray mass spectrometry.  J Ethnopharmacol. 2004;  93 109-12
• 7 Gu Z P, Zhang S M, Wang C L, Xiao P G. Determination of strychnine and brucine in Strychni and its preparation by gas chromatography.  Acta Pharm Sin. 1997;  32 791-4
• 8 Guo J F, Chen X Y, Zhong D F. Identification of strychnine, brucine and their metabolites in body fluids by liquid chromatography-electrospray ion trap mass spectrometry.  Yaowu Fenxi Zazhi. 2001;  21 167-70
• 9 Cai B C, Hattori M, Namba T. Processing of nux-vomica. II. Changes in alkaloids composition of the seeds of Strychnos nux-vomica on traditional drug-processing.  Chem Pharm Bull. 1990;  38 1295-8
• 10 Cai B C, Wang T S. Cytotoxicities of alkaloids from processed and unprocessed seeds of Strychnos nux-vomica. .  Acta Pharm Sin. 1998;  19 425-8
• 11 Wu Y, Wang T S, Yin F Z, Cai B C. Analgesic and anti-inflammatory properties of brucine and brucine N-oxide extracted from seeds of Strychnos nux-vomica. .  J Ethnopharmacol. 2003;  88 205-14
• 12 Lu Y C, Lin P C, Ji L J, Hu F Z. Determination of three bioactive ingredients of Gentiana aristata Maxim.  Chin Trad Pat Med. 2005;  27 1356-7