24R-Methylcholestan-3beta-ol, commonly known as brassicasterol, is a C28 phytosterol characterized by a cholestane skeleton with a methyl group at the C-24 position and a double bond between C-22 and C-23. It is a key sterol component found in various plant sources, particularly in the Brassicaceae family (e.g., rapeseed, mustard), as well as in some algae and fungi. Brassicasterol is widely studied as a biomarker for distinguishing plant-derived organic matter in environmental and geological samples. In the pharmaceutical and nutraceutical industries, it is recognized as a component of plant sterol mixtures, which are used as functional food ingredients and dietary supplements for their potential cholesterol-lowering effects. Its presence and ratio to other sterols are also important in the quality control of vegetable oils and in the authentication of certain food products. As a natural sterol, brassicasterol is investigated for its potential biological activities, including anti-inflammatory and antioxidant properties. It serves as a valuable reference standard in analytical chemistry for the quantification of sterol profiles.