Digitonide precipitable sterols: A reevaluation with special attention to lanosterol

Document Type

Article

Publication Title

Lipids

Abstract

The ability of digitonin to precipitate lanosterol from prepared mixtures and biological sources was evaluated. Commercially available lanosterol was determined to be composed of about 60% lanosterol and 40% dihydrolanosterol. Both sterols were only partially precipitated by digitonin under all conditions examined. The presence of cholesterol increased the precipitation of lanosterol, but never to completion. About 40% of the lanosterols from saponified sheep's-wool fat was not precipitated by digitonin. Also14C-labeled lanosterol recovered from rat brain following intracerebral injection of 2-[14C] mevalonate was only 70% precipitated by digitonin. Steric hinderance by the methyl groups at carbon -4 is suggested to explain the poor precipitability of this sterol. In conclusion, lanosterol can not be considered to be a digitonide-precipitable sterol equivalent to cholesterol. Caution should be exercised in situations where digitonin-precipitable sterols are being prepared from sources containing significant concentrations of lanosterol (i.e., mass and/or radiolabel). © 1982 American Oil Chemists' Society.

First Page

443

Last Page

447

DOI

10.1007/BF02535224

Publication Date

6-1-1982

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