Cytotoxicity assessment of ma-huang (Ephedra) under different conditions of preparation

Ma-huang is a traditional Chinese medicinal herb derived from Ephedra sinic a Stapf and other Ephedra species, used to treat asthma, nose and lung cong estion, and fever with anhidrosis. It contains 0.5-2.5% by weight of total alkaloids, of which ephedrine accounts for 30 to 90%. Recently, large amoun ts of ma-huang were used as a source of ephedrine in many dietary supplemen ts formulated for weight reduction, because ephedrine has been found effect ive in inducing weight loss in diet-restricted obese patients. However, ind iscriminate consumption of ma-huang-containing products has resulted in man y cases of poisoning, some of which were fatal. The objective of this study is to investigate the relative toxicity of ma-huang extracted under differ ent conditions. The toxicities of various extracts were assayed using MTT c olorimetry on a battery of cell lines, while ephedrine alkaloids were analy zed with HPLC. The results are summarized as follows. (1) The cytotoxicity of all ma-huang extracts could not be totally accounted for by their ephedr ine contents, suggesting the presence of other toxins in the extracts. (2) Grinding was a significant condition enhancing the toxicity of the extracts . (3) The relatively high sensitivity of the Neuro-2a cell line to the toxi city of ma-huang extracts suggests that the toxic principles were acting on neuronal cells. (4) One condition to produce a ma-huang extract with high ephedrine-to-toxins ratio would be to boil the whole herb for two h.