In organisms that live in the marine world, sterol methylation patterns vary greatly and reflect the complexity of mixtures of sterols arising through the food chain.
Sterols in fungi typically exist as a mixture of several sterols with one that is dominant, i.e., representing over 50% of the total sterol composition.
Chemically, lanolin consists of a mixture of several sterols, fatty acids, and their esters.
A complex mixture of plant sterols and stanols were also present, consistent with an herbivorous diet.
Analysis of the Shasta ground sloth coprolites (approximately 12,000 years old) showed the predominant presence of glycine-conjugated bile acids, similar to analyses of bile and feces of living sloths, in addition to a complex mixture of plant sterols and stanols expected from an herbivorous diet.
Higher plants are a mixture of 24-alkylated sterols, 24-ethyl and 24-methyl sterols generally accounting, respectively, for more than 70% and less than 30% of the total sterol.
The sterol fraction of Glycine max (soybean) was found to contain a mixture of 13 major sterols which differed dramatically in composition between seeds and shoots.
Typical C4-desmethyl Δ5-sterols, including sitosterol, predominate the sterol mixture of shoots, whereas C4-methyl sterol intermediates, cycloartenol and 24(28 -methylene cycloartanol, accumulate in seeds.
(17) On the other hand, the size and direction of the 24-alkyl group have phylogenetic significance; 24β-methyl sterols predominate in less-advanced organisms, including many fungi and protozoa, and 24α-ethyl sterols populate the sterol mixture of advanced organisms, typified by vascular plants.
The cell membrane also contains a mixture of distinct lipids and sterols specific to the cell type.
