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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: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only
Publication Acceptance Date: May 14, 1997
Publication Date: N/A

Technical Abstract: Milkweed plants (Asclepias spp., asclepiadaceae) biosynthesize a variety of secondary metabolites including cardiac glycosides (cardenolides) which are stored in roots, stems, seeds and leaves of the plant. At the present, only the seed floss, a fine fiber attached to the seed, is used commercially as an insulating fiber fill. Finding uses for other plant components (oil content and seed meal) will depend largely on the ability to detect, and if present, to separate the bioactive cardenolides from either oil or meal. A procedure was developed to detect and quantify cardenolide content of oil extracted from milkweed (A. syriaca) seed using an Hitachi U-2000 spectrophotometer and a modification of a procedure by Brower et al. 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: 8/27/2014
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