The Sterols of Alfalfa and Certain Cereal Grasses

Abstract

Little attention has been given to the sterols of the vegetative portion of green plants. This perhaps has been due partially to the difficulty of determining sterols quantitatively in the presence of chlorophyll and carotenoids. With an increase in the use of certain sterols for the production of pharmaceuticals, attention has been directed again to the sterols of green plant tissue, with methods being developed to facilitate their estimation (5). The study reported herein was undertaken to determine the nature and the amount of the sterols in the lipid fraction of some crops which are suitable for commercial dehydration, for such dehydrated mat-erial would be the logical source for the production of sterols from green plants if they are found to be economically important.Determination and characterization of sterols Fresh plant tissue was autoclaved for five minutes at 10 pounds pressure, and dried at 650 C for four hours. The dried material was ground to pass through a 20-mesh screen. Sterols were determined quantitatively by the colorimetric method of WALL and KELLEY (5), which consists of extracting the dried plant tissue with Skellysolve B, removing chlorophyll and xanthophyll by adsorption, precipitating carotene with iodine, precipitating the sterols with digitonin, and subjecting the resulting sterol digitonide to the Liebermann-Burchard reaction. A standard curve was established for each plant tissue to be studied by isolating the sterol with digitonin (5) and dissolving a weighed amount of the sterol digitonide in acetic acid. Aliquots of this solution were subjected to the Liebermann-Burchard reaction, and the intensity of the color produced was measured with a Beckman spectrophotometer. The digitonide of alfalfa sterol has an absorption maximum at 680 mu (5). Absorption maxima for the digitonides of the sterols of brome grass and the wheat plant were found at 680 mu also (fig.