Ma-huang is a traditional Chinese medicinal herb derived from the stems and branches of Ephedru sinica Stapf and other Ephedra species. For centuries, it has been used to treat asthma, nose and lung congestion, and fever with anhidrosis....[ Read more ]

Ma-huang is a traditional Chinese medicinal herb derived from the stems and branches of Ephedru sinica Stapf and other Ephedra species. For centuries, it has been used to treat asthma, nose and lung congestion, and fever with anhidrosis.

Ma-huang contains 0.5 - 2.5% by weight of total alkaloids, of which ephedrine accounts for 30 to 90%. Ephedrine has been found to cause thermogenic and lipolytic effects on basal metabolism in lean, obese and post-obese humans and is effective in inducing weight loss in diet-restricted obese patients. Recently, large amounts of ma-huang were used as a source of ephedrine in many dietary supplements used for weight reduction. However, indiscriminate consumption of these ma-huang containing products has resulted in many cases of poisoning and undesirable effects, some of which were fatal.

The objective of this research is to investigate the relative toxicity of ma-huang, extracted alone and with other selected herbs, under different conditions. The toxicities of various extracts were assayed using MTT calorimetry on a battery of cell lines, while ephedrine alkaloids were analyzed with HPLC analyses as active principles. In addition, the ability of ephedrine and ma-huang extracts to potentiate CCl₄ as a model hepatoxicant was investigated, using the HepG2 cell line. The results are summarized as follows. 1) In these bioassays, the toxicity of all ma-huang extracts could not be totally accounted for by their ephedrine contents, suggesting the presence of other toxins in the extracts. Some of these toxins could be removed by solid phase extraction. 2) Grinding was the most significant condition enhancing the release of toxins. 3) Neuro-2a cell line was significantly more sensitive to the cytotoxicity of ma-huang extracts, suggesting that the toxic principles were acting on neuronal cells. 4) The best condition to produce a ma-huang extract with maximal ephedrine to toxins ratio would be to boil the whole herb for two hours; this condition substantiates the "long-period extraction" as advocated in some of the traditional Chinese medicinal literature. 5) The extraction efficiencies of ephedrine and the cytotoxic potency of ma-huang extracts varied when ma-huang was extracted with other selected herbs. 6) Ephedrine could potentiate the cytotoxicity of CCl₄ to HepG2 cell line, suggesting that consumption of even non-toxic doses of ephedrine may increase the chance of liver injuries caused by some hepatotoxicants.