Macroscopic and Microscopic Authentication of Chinese and North American Species of Ephedra

Ephedra sinica Stapf or Ma Huang has been used in traditional Chinese medicine for over 5000 years as a bronchodilating and stimulatory agent. In the West, it is popularly used in dietary supplements for weight loss and to enhance athletic performance. Adverse events have been reported following consumption of dietary supplements containing ephedrine alkaloids. There are about 50 known species of Ephedra. The ratio of ephedrine to other alkaloids varies from species to species; all North American species lack alkaloids. The method commonly used in the dietary supplement industry for botanical authentication is to analyze the product for the presence of chemical markers known to be present in the specific herb. However, this method does not ensure that the product contains authentic herb, especially if it has been spiked with chemical marker compounds. In the trade and raw drug market, Ephedra is available in the form of stem cuttings or powders, without any vouchers, thus making identification of the species difficult. Using light microscopy, we can detect the presence of Ephedra herb, even in powder form, and identify within certain limits its geographical origin. Identification of Chinese and North American species of Ephedra has been made easier by developing a key using leaf and internode length as key identification characters.