49I-11 |
|
K. FUKUSHIMA, Department of Nutrition and Food Science/Food Bioprocess Engineering Lab, University of Maryland, 3407 Marie Mount Hall, College Park, MD 20742, P. Jing, Nutrition and Food Science, University of Maryland, 3407 Marie Mount Hall, College Park, MD 20742, and Y. M. Lo, Dept. of Nutrition & Food Science, Univ. of Maryland, Food Bioprocess Engineering Lab., 3102 Marie Mount Hall, College Park, MD 20742. Used in the Far East to treat asthma, nose and lung congestion, and fever, Ephedra is the major source of ephedrine-type alkaloids (ETA). Indiscriminate consumption of ETA-containing products has resulted in more than 1,100 reported cases of poisoning and other serious side effects since 1993. The quality of Ephedra is usually determined by the contents of total ETA. However, although individual ETA has similar pharmacological activity, they vary significantly in potency. Therefore, to characterize the toxicity of Ephedra, a bioassay is needed to correlate its bioactivity with ETA contents. The objective was to evaluate the bioactivity of Ephedra by measuring its cytoxicity against representative cell lines and analyzing the stress responses of a panel of biosensing strains specific to cell damages. Various dietary supplements containing ETA were studied. Rat myocardium cell line H9c2(2-1), which exhibits the properties of skeletal muscle, and human neuroblastoma cell line SH-SY5Y were used to conduct preliminary screening of potential cytotoxicity. MTT cell proliferation assay was used to measure the cell viability after exposure to Ephedra. A panel of six bioluminescent strains containing selected stress-responsive E. coli promoters fused to the Photorhabdus luminescens luxCDABE reporter was used. The ETA contents of the supplements were analyzed using HPLC. Both cell lines were sensitive to the presence of ETA with responses distinctive among different supplements. However, the inhibitory concentration 50% (IC50) data did not increase linearly (R2>0.95) with increasing ETA concentrations, suggesting the presence of other bioactive compounds in the supplements. The stress fingerprints showed increased expression of the lux gene fusion at increased ETA concentration, indicating characteristic sigma S stress in response to ETA. Not only will this novel bioassay enable rapid screening of Ephedra bioactivity, the knowledge obtained from the damage on the sensing cells will help define the role of Ephedra for discriminative uses.
Session 49I, Toxicology & Safety Evaluation: General
|