lanostane

Lanostane is a tetracyclic triterpene hydrocarbon that provides the core four-ring skeleton used in the biosynthesis of sterols. It contains a 30-carbon framework that serves as the structural basis for a variety of biologically important molecules, including lanosterol and other sterols derived through further oxidation and side-chain modifications.

Structurally, lanostane resembles the steroid nucleus with an aliphatic side chain attached to the ring system. The lanostane framework is the basis from which many oxygenated sterols are produced, and it is commonly discussed in the context of steroid biosynthesis and natural product chemistry. The precise arrangement of rings and substituents distinguishes lanostane from related skeletons used in different sterols.

In biochemical pathways, the lanostane-type skeleton arises during the cyclization of oxidosqualene, a key early step in sterol biosynthesis. The enzyme oxidosqualene cyclase converts a linear precursor into the lanostane core, which can then undergo various oxidations, demethylations, and side-chain modifications to yield lanosterol in fungi and animals, or related sterols such as cholesterol and ergosterol in other organisms. The lanostane framework thus plays a central role in the diversification of sterols, which are essential components of cell membranes and precursors to other biologically active molecules.

Because of its prominence in sterol chemistry, lanostane is frequently discussed in natural product chemistry, biochemistry, and pharmacology as the foundational hydrocarbon skeleton for a broad family of sterols.