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Identification of 27‐nor‐(24 R )‐24‐methylcholesta‐5,22‐dien‐3β‐ol and brassicasterol as the major sterols of the marine dinoflagellate Gymnodinium simplex
Author(s) -
Goad L. John,
Withers Nancy
Publication year - 1982
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02534578
Subject(s) - dinoflagellate , sterol , chemistry , biology , stereochemistry , chromatography , biochemistry , botany , cholesterol
The major 4α‐monomethyl sterol of the dinoflagellate Gymnodinium simplex was identified as (24 S )‐4α,24‐ dimethylcholestan‐3β‐ol. The major 4‐demethyl sterols were characterized as (24 R )‐24‐methylcholesta‐5,22‐dien‐3β‐ol (brassicasterol) and 27‐nor‐(24 R )‐24‐methylcholesta‐5,22‐dien‐3β‐ol. The latter sterol has the opposite configuration at C‐24 to that assigned to occelasterol, which has the same basic structure and has previously been reported as a constituent of the sterols of a marine worm. 24‐Nor‐cholesta‐5,22‐dien‐3β‐ol was also identified along with several other trace sterols. The co‐occurrence of 27‐nor‐(24 R )‐cholesta‐5,22‐dien‐3β‐ol together with 24‐nor‐cholesta‐5,22‐dien‐3β‐ol and brassicasterol provides new evidence for the biosynthetic origins of the two former nor‐sterols. It is suggested that they may be produced de novo by a route involving nor‐isoprenoid pyrophosphates and nor‐squalene as intermediates, rather than as bacterial degradation products of brassicasterol (or related sterols) as previously suggested in the literature.