Sterol Biosynthesis in Euglena gracilis Z.

Abstract

Squalene, squalene‐2,3‐oxide, triterpenes and 4α‐methylsterols of Euglena gracilis Z. have been characterised by thin‐layer chromatography, gas chromatography and mass spectrometry. Their distribution in dark‐grown and light‐grown Euglena cells is quantitatively and qualitatively different, reflecting differences in the sterol compositions. However the sterol precursor is found to be in each case cycloartenol, whereas lanosterol is not detected. A new 4α‐methylsterol is isolated and the structure of 4α‐24‐dimethyl‐5α‐cholesta‐8(9)‐en‐3ß‐ol proposed. 24‐Methylene lanostenol is formed in light‐grown Euglena. None of the compounds described have been found in water‐soluble fractions nor in the form of fatty‐acid esters. The following compounds have also been isolated: 24‐methylene cycloartanol, 24‐methylene agnostenol (?), ß‐amyrin, obtusifoliol, 24‐methylene lophenol and 4α‐methylzymosterol.