Sitosterol is a plant sterol, with only a small difference from cholesterol - an extra ethyl group -C₂H₅.

Sitostanol is a plant stanol, with only one small difference from sitosterol - a single bond rather than a double bond on one of the rings.

As their names suggest, these compounds are alcohols, possessing an - OH group which can react with acids to form esters.

Shown below is an ester of sitostanol - sitostanyl oleate.

Sitostanyl oleate is an ester formed between sitostanol and the (mono-unsaturated) fatty acid oleic acid .