The unsaponifiables of Vernonia anthelmintica seed oil

Abstract

The unsaponifiable fraction of Vernonia anthelmintica seed oil has been studied in detail. Preparative thin layer chromatography (TLC) on argentated plates has revealed that the hydrocarbon fraction contains squalene as well as normal odd chain alkanes among which C31 predominates. A small fraction containing C18-C28 n-alcohols was also found. The sterol fraction made up the bulk of the unsaponifiables (66%). This fraction contained at least six sterols but two of these accounted for over 90% of the total. The sterols occur in the oil in the esterified form; gas liquid chromatography shows that they are preferentially esterified to linoleic acid. These esters have been isolated by column chromatography on silica gel and have been separated by preparative TLC. Purification by preparative TLC followed by high resolution mass spectrometry has shown that empirical formulas of the two most abundant sterols are C29H46O and C29H48O. The latter corresponds to the already reported Δ7-avenasterol. The former is a new sterol having three double bonds and a stigmastane backbone. © 1968 The V. D. Anderson Co.