The role of chemical fingerprinting: application to Ephedra

Ephedra sinica, known as Ma Huang, is one of the oldest medicinal herbs in Traditional Chinese Medicine (TCM). Preparations, namely teas, of E. sinica have been used for over 5000 years as a stimulant and as an antiasthmatic. In the West, extracts of E. sinica, E. intermedia or E. equisetina are most commonly used in dietary supplements as a stimulant and to promote weight loss. More than 50 species of Ephedra are native to both hemispheres, but the detection of ephedrine alkaloids has been limited to species in Eurasia. Currently, methods exist to quantitate the ephedrine alkaloids in extracts of plant material or dietary supplements, but the methods are not able to verify the extract is of an Ephedra species. Reverse phase high performance liquid chromatography with photodiode array detection was applied for the chemical fingerprinting of the Ephedra species. Two regions of comparison were determined in the chromatograms at 320 nm. The series of peaks between 52 and 64 min confirms an Ephedra species is being analyzed. The aforementioned peaks also could distinguish between Ephedra species from Eurasia, North America and South America. Peaks at ca. 57 and 59 min were isolated and determined to be two new compounds, 4-(2-eicosyloxycarbonyl-vinyl)-benzoic acid and 4-(2-docosyloxycarbonyl-vinyl)-benzoic acid respectively. Authentication of ground plant material as Ephedra can be achieved by this chemical fingerprinting method.