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United States Department of Agriculture

Agricultural Research Service

Title: Quantitative Determination of Gross Cardenolide Content of Cold-Pressed Milkweed Oil

Authors
item Harry-O`kuru, Rogers
item Abbott Dr, Thomas

Submitted to: Journal Of Industrial Crops And Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 17, 1997
Publication Date: N/A

Interpretive Summary: Milkweed is one of the new industrial crops. To be successful, the resources of such a crop must be economically marketed in order to justify investment. For milkweed, however, only the floss (a fine fiber attached to the seed for wind dispersal) is presently in demand in the comfort arena as a fiber fill. The other resources of the seed (oil content rich in E-vitamins and the seed meal) need to find markets but for the bioactive compounds called cardenolides suspected to be present in the seed. To explore the possibility of utilizing all or part of the resources of the seed, we have recently developed an analytical test in our laboratory for detecting very minute amounts of cardenolides. The results from this test procedure on cold-pressed and solvent-extracted milkweed oils indicate no cardenolides in the oils tested. The importance of these results would very likely move this new industrial crop one step closer to profitability for producers and a new renewable source of domestically produced vegitable oil for consumers.

Technical Abstract: A procedure was developed to detect and quantify cardenolide content of oil extracted from the seed of the common milkweed (Asclepias syriaca) using an Hitachi U-2000 spectrophotometer. The technique exploits the reaction of 2,2',4,4' tetranitrobiphenyl (TNBP), with cardenolides to form colored complexes in the presence of NaOH. The complex has an absorbance maximum at 620 nm with intensity maximum usually attained in 40 min after NaOH addition. Digitoxin, a known cardiac glycoside, was employed in generating standard calibration curves for the analysis. Absorbance spectra of A. syriaca cold-pressed and petroleum ether extracted oil samples as well as food-grade commercial vegetable oils, were compared to those of standards in order to detect and estimate their cardenolide content. No cardenolides were found in A. syriaca oil at detection limits of <1 ppm.

Last Modified: 12/25/2014
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