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Dihydrocholesterol (cholestanol; 5α-cholestan-3β-ol) is a cholesterol metabolite formed by oxidation and an intermediate in the biosynthesis of chenodeoxycholic acid . Cholestanol (10 μg/ml) induces apoptosis in cornea and lens epithelial cells and increases the activity of IL-1β converting enzyme (ICE) and CPP32 proteases. Dietary administration of 1% cholestanol to mice increases serum and liver cholestanol levels and leads to corneal opacities and gallstones and in rats it leads to cholestanol deposition in the cerebellum. Cholestanol levels are increased in plasma of patients with cerebrotendinous xanthomatosis (CTX), a disease characterized by a deficiency in the mitochondrial enzyme sterol 27-hydrolylase (CYP27A1) that leads to progressive neurological symptoms.

It appears as a white crystalline powder and is odourless. The substance is insoluble in water but readily soluble in organic solvents such as chloroform, ethanol and diethyl ether.¹ Its specific rotation is +24.2° (22 °C, in chloroform).

5α-Cholestan-3β-ol is a carbon stanol formed from biohydrogenation of Cholesterol (C432501) in the gut. Studies have also examined the conversion of 5α-Cholestan-3β-ol catalyzed by 3-β-hydroxysteroid dehydrogenase of rat liver.

ChEBI: A cholestanoid that is (5alpha)-cholestane substituted by a beta-hydroxy group at position 3.

Dihydrocholesterol can be prepared either by chemical synthesis or by extraction from natural sources. Chemical synthesis typically uses cholesterol as the starting material. Hydrogenation is carried out in a solvent such as glacial acetic acid using a catalyst, for example platinum oxide, to reduce the C5–C6 double bond, followed by purification through saponification and crystallisation. Alternatively, dihydrocholesterol may be isolated from natural materials, including animal tissues such as bovine brain and liver, or purified from gallstones.

5α-Cholestan-3β-ol is derived from cholesterol by the action of intestinal microorganisms. It is known to induce the formation of gall stones in rabbits in the presence of sodium ions.

Purify 5--cholestan-3-ol via acetylation, crystallisation and de-acetylation, then recrystallisation from EtOH or slightly aqueous EtOH, or MeOH. Its solubility is: 0.5% (MeOH) and 1% (EtOH) at 25o. [Mizutani & Whitten J Am Chem Soc 107 3621 1985.] The acetate has m 114-115o from EtOAc/MeOH and, [] D 20 +13o (c 2, CHCl3). [Bruce & Ralls Org Synth Col Vol II 191 1943, Beilstein 6 IV 3577.]

The chemical structure of dihydrocholesterol is very similar to that of cholesterol, as both compounds possess the cyclopentanoperhydrophenanthrene steroid nucleus. Its structural features include a β-hydroxyl group at the C3 position of the steroid nucleus and an aliphatic side chain attached at the C17 position. Unlike cholesterol, the C5–C6 double bond is hydrogenated and converted into a saturated single bond in dihydrocholesterol. Accordingly, dihydrocholesterol is systematically named 5α-cholestan-3β-ol.

[1] S SERIZAWA. Studies on the biosynthesis of cholestanol in cultured cells.[J]. Journal of biochemistry, 1982, 92 5: 1547-1557. DOI: 10.1093/oxfordjournals.jbchem.a134079
[2] K INOUE. Cholestanol induces apoptosis of corneal endothelial and lens epithelial cells.[J]. Investigative ophthalmology & visual science, 2000, 41 5: 991-997.
[3] SEYAMA Y. Cholestanol metabolism, molecular pathology, and nutritional implications.[J]. Journal of medicinal food, 2003, 6 3: 217-224. DOI: 10.1089/10966200360716634
[4] B. PILO DE LA FUENTE . Usefulness of cholestanol levels in the diagnosis and follow-up of patients with cerebrotendinous xanthomatosis[J]. Neurologia, 2011, 26 7: Pages 397-404. DOI: 10.1016/j.nrleng.2010.12.002
[5] Nes*, W. David. “Biosynthesis of Cholesterol and Other Sterols.” Chemical Reviews, 111 10, 2011, pp. 6423–51, https://doi.org/10.1021/cr200021m.