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United States Department of Agriculture

Agricultural Research Service

Title: Analysis of Swainsonine: Extraction Methods, Detection, and Measurement in Populations of Locoweeds (Oxytropis SPP.)

Authors
item Gardner, Dale
item Molyneux, Russell
item Ralphs, Michael

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 30, 2001
Publication Date: September 13, 2001
Citation: GARDNER, D.R., MOLYNEUX, R.J., RALPHS, M.H. ANALYSIS OF SWAINSONINE IN LOCOWEEDS (OXYTROPIS SPP.): EXTRACTION METHODS AND DETECTION USING LIQUID CHROMATOGRAPHY AND TANDEM MASS SPECTROMETRY. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY. 2001.

Interpretive Summary: An analytical method to measure the locoweed toxin, swainsonine, in locoweed plants was developed. After drying and grinding, plant material is extracted using a small-scale liquid/liquid extraction procedure followed by isolation of the swainsonine by solid phase extraction with a cation exchange resin. Detection and quantitation of the extracted swainsonine is accomplished using reverse phase high performance liquid chromatography coupled to atmospheric pressure chemical ionization tandem mass spectrometry (LC/MS2). The limit of quantitation was estimated to be 0.001% swainsonine by weight in dry plant material and corresponds to a general threshold of plant toxicity. A large number of Oxytropis sericea (white locoweed) and O. lambertii (Lambert locoweed) plants were analyzed for swainsonine and the swainsonine concentration in the plants was found to be highly variable. The combined three year mean swainsonine values taken from three populations of O. sericea ranged from 0.046% in Utah to 0.097% in a New Mexico population. Sixteen individual populations of O. lambertii were sampled from eight different U. S. states. Only five of the 16 populations were found to contain high enough concentration of swainsonine to be considered toxic. The toxic populations of O. lambertii were restricted to the most southern and western portion of its distribution and all were identified as belonging to var. bigelovii.

Technical Abstract: An analytical method has been developed to measure the locoweed toxin, swainsonine, in locoweed plant material. Dry ground plant samples were extracted using a small-scale liquid/liquid extraction procedure followed by isolation of the swainsonine by solid phase extraction with a cation exchange resin. Detection and quantitation of the swainsonine were accomplished using reverse phase high performance liquid chromatography coupled to atmospheric pressure chemical ionization tandem mass spectrometry (LC/MS2). The limit of quantitation was estimated to be 0.001% swainsonine by weight in dry plant material which corresponds to the lower threshold for toxicity of locoweeds. The methods of analysis was applied to the analysis of Oxytropis sericea (white locoweed) and O. lambertii (Lambert locoweed) plant samples to measure the variability of individual plant swainsonine levels within populations and within species. Individual plant variability was found to be highly significant for both O sericea and O. lambertii populations. The combined three year mean swainsonine values taken from three populations of O. sericea ranged ranged from 0.046% in Utah to 0.097% in a New Mexico population. Sixteen individual populations of O. lambertii were sampled from eight different U.S. states. Swainsonine was detected at levels greater than 0.001% in only five of the 16 collection sites. Those populations of O. lambertii found to contain higher swainsonine levels were restricted to the most southern and western portion of its distribution and all were identified as belonging to var. bigelovil, whereas var. articulata and var. lambertii samples contained swainsonine at levels below 0.001%

Last Modified: 9/23/2014
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