Cholestanes

Cholesterol is the principal sterol of all animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.

thumb|250px|right|The epidermal strata of the skin

thumb|Numbering of the carbon atoms. In steranes, the side chain at C-17 varies.

chemical compound

Brassicasterol (24-methyl cholest-5,22-dien-3β-ol) is a 28-carbon sterol synthesised by several unicellular algae (phytoplankton) and some terrestrial plants, like rape. This compound has frequently been used as a biomarker for the presence of (marine) algal matter in the environment, and is one of the ingredients in stigmasterol-rich plant sterols (Number E499 in the European numbering system).

Lathosterol is a cholesterol-like molecule found small amounts in humans. The enzyme Δ7-sterol 5(6)-desaturase converts it to 7-dehydrocholesterol. It is accumulated in lathosterolosis.

Cholestane is a saturated tetracyclic steroid biosynthetically derived from triterpenoids. This 27-carbon biomarker is produced by diagenesis of cholesterol and is one of the most abundant biomarkers in the rock record. Presence of cholestane, its derivatives and related chemical compounds in environmental samples is commonly interpreted as an indicator of animal life and/or traces of O2, as animals are known for exclusively producing cholesterol, and thus has been used to draw evolutionary relationships between ancient organisms of unknown phylogenetic origin and modern metazoan taxa. Cholest

Desmosterol (cholesta-5,24-dien-3β-ol) is a lipid present in the membrane of phytoplankton and an intermediate product in cholesterol synthesis in mammal cells. Structurally, desmosterol has a similar backbone to cholesterol, with the exception of an additional double bond in the structure of desmosterol.

5β-Coprostanol (5β-cholestan-3β-ol) is a 27-carbon stanol formed from the net reductive metabolism of cholesterol (cholest-5en-3β-ol) in the gut of most higher animals and birds. This compound has frequently been used as a biomarker for the presence of human faecal matter in the environment. 5β-coprostanol is thought to be exclusively bacterial in origin.

Zymosterol is an intermediate in cholesterol biosynthesis. Disregarding some intermediate compounds (e.g. 4-4-dimethylzymosterol), lanosterol can be considered a precursor of zymosterol in the cholesterol synthesis pathway. The conversion of zymosterol into cholesterol happens in the endoplasmic reticulum. Zymosterol accumulates quickly in the plasma membrane coming from the cytosol. The movement of zymosterol across the cytosol is more than twice as fast as the movement of cholesterol itself.

7-Dehydrodesmosterol (or cholesta-5,7,24-trien-3-beta-ol) is a cholesterol intermediate.

Iodocholesterol, or 19-iodocholesterol, also as iodocholesterol (131I) (INN) and NP-59, is a derivative of cholesterol with an iodine atom in the C19 position and a radiopharmaceutical. When the iodine atom is a radioactive isotope (iodine-125 or iodine-131), it is used as an adrenal cortex radiotracer in the diagnosis of patients suspected of having Cushing's syndrome, hyperaldosteronism, pheochromocytoma, and adrenal remnants following total adrenalectomy.

chemical compound

Acebrochol (INN), also known as cholesteryl acetate dibromide or 5α,6β-dibromocholestan-3β-ol acetate, is a neuroactive steroid which was described as a sedative and hypnotic but was never marketed.

'20α,22R-Dihydroxycholesterol, or (3β)-cholest-5-ene-3,20,22-triol' is an endogenous, metabolic intermediate in the biosynthesis of the steroid hormones from cholesterol. Cholesterol ((3β)-cholest-5-en-3-ol) is hydroxylated by cholesterol side-chain cleavage enzyme (P450scc) to form 22R-hydroxycholesterol, which is subsequently hydroxylated again by P450scc to form 20α,22R-dihydroxycholesterol, and finally the bond between carbons 20 and 22 is cleaved by P450scc to form pregnenolone ((3β)-3-hydroxypregn-5-en-20-one), the precursor to the steroid hormones.

'22R-Hydroxycholesterol, or (3β)-cholest-5-ene-3,22-diol' is an endogenous, metabolic intermediate in the biosynthesis of the steroid hormones from cholesterol. Cholesterol ((3β)-cholest-5-en-3-ol) is hydroxylated by cholesterol side-chain cleavage enzyme (P450scc) to form 22R-hydroxycholesterol, which is subsequently hydroxylated again by P450scc to form 20α,22R-dihydroxycholesterol, and finally the bond between carbons 20 and 22 is cleaved by P450scc to form pregnenolone ((3β)-3-hydroxypregn-5-en-20-one), the precursor to the steroid hormones.

chemical compound

chemical compound

27-Hydroxycholesterol (27-HC) is an endogenous oxysterol with multiple biological functions, including activity as a selective estrogen receptor modulator (SERM) (a mixed, tissue-specific agonist-antagonist of the estrogen receptor (ER)) and as an agonist of the liver X receptor (LXR). It is a metabolite of cholesterol that is produced by the enzyme CYP27A1.

'24S-Hydroxycholesterol (24S-HC), also known as cholest-5-ene-3,24-diol or cerebrosterol', is an endogenous oxysterol produced by neurons in the brain to maintain cholesterol homeostasis. It was discovered in 1953 by Alberto Ercoli, S. Di Frisco, and Pietro de Ruggieri, who first isolated the molecule in the horse brain and then demonstrated its presence in the human brain.