C27H46O

C27H46O is the molecular formula for cholesterol, the most abundant sterol in animals and an essential structural component of animal cell membranes. It functions as a modulator of membrane fluidity and permeability and serves as the metabolic precursor for a variety of biosynthetic pathways, including the synthesis of bile acids and steroid hormones.

Cholesterol has a tetracyclic cyclopenta[a]phenanthrene ring system with a single hydroxyl group at the 3β position and a hydrophobic 8-carbon side chain, giving a total of 27 carbon atoms. Its IUPAC name is (3β)-cholest-5-en-3-ol. The molecule is highly lipophilic and is largely insoluble in water, with solubility in organic solvents.

Cholesterol is produced endogenously mainly in the liver and also obtained from dietary animal products. Biosynthesis proceeds via the mevalonate pathway from acetyl-CoA, with HMG-CoA reductase as the rate-limiting enzyme, a key target of statin medications. It is transported in blood by lipoproteins, with LDL delivering cholesterol to tissues and HDL involved in reverse transport.

Physiologically, cholesterol is a critical component of cell membranes and a precursor to bile acids, which aid digestion, and to steroid hormones such as cortisol, aldosterone, and the sex hormones. Imbalances in cholesterol levels are associated with cardiovascular disease, leading to medical strategies that regulate its synthesis, absorption, and transport.