Cholesterol is the principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.
A steroid is an organic compound with four fused rings arranged in a specific molecular configuration.
Adolf Otto Reinhold Windaus was a German chemist who won a Nobel Prize in Chemistry in 1928 for his work on sterols and their relation to vitamins. He was the doctoral advisor of Adolf Butenandt who also won a Nobel Prize in Chemistry in 1939.
Sterol is an organic compound with formula C
17H
28O, whose molecule is derived from that of gonane by replacement of a hydrogen atom in position 3 by a hydroxyl group. It is therefore an alcohol of gonane. More generally, any compounds that contain the gonane structure, additional functional groups, and/or modified ring systems derived from gonane are called steroids. Therefore, sterols are a subgroup of the steroids. They occur naturally in most eukaryotes, including plants, animals, and fungi, and can also be produced by some bacteria. The most familiar type of animal sterol is cholesterol, which is vital to cell membrane structure, and functions as a precursor to fat-soluble vitamins and steroid hormones.
Phytosterols are phytosteroids, similar to cholesterol, that serve as structural components of biological membranes of plants. They encompass plant sterols and stanols. More than 250 sterols and related compounds have been identified. Free phytosterols extracted from oils are insoluble in water, relatively insoluble in oil, and soluble in alcohols.
Smith–Lemli–Opitz syndrome is an inborn error of cholesterol synthesis. It is an autosomal recessive, multiple malformation syndrome caused by a mutation in the enzyme 7-Dehydrocholesterol reductase encoded by the DHCR7 gene. It causes a broad spectrum of effects, ranging from mild intellectual disability and behavioural problems to lethal malformations.
Campesterol is a phytosterol whose chemical structure is similar to that of cholesterol, and is one of the ingredients for E number E499.
Stigmasterol – a plant sterol (phytosterol) – is among the most abundant of plant sterols, having a major function to maintain the structure and physiology of cell membranes. In the European Union, it is a food additive listed with E number E499, and may be used in food manufacturing to increase the phytosterol content, potentially lowering the levels of LDL cholesterol.
Steranes constitute a class of tetracyclic triterpanes derived from steroids or sterols via diagenetic and catagenetic degradation, such as hydrogenation. They are found in sediments and sedimentary rocks in nature. Steranes are derivatives of gonane, the steroid nucleus which is also called "cyclopentanoperhydrophenanthrene". They have an androstane skeleton with a side chain at carbon C-17. The sterane structure constitutes the core of all sterols. Steranes are widely used as biomarkers for the presence of eukaryotes in past ecosystems because steroids are nearly exclusively produced by eukaryotes. In particular, cholestanes are diagenetic products of cholesterol in animals, while stigmastanes are diagenetic products of stigmasterols in algae and land plants. However, some bacteria are now known to produce sterols and it is inferred that the ultimate origin of sterol biosynthesis is in bacteria. Sterols are produced via protosterols that are direct cyclization compounds of squalene by the catalysis of oxidosqualene cyclase. All known sterols in eukaryotes are enzymatically extensively modified from protosterols, while organisms that only produce protosterols are not known. The oldest record of modified steranes are in sedimentary rocks deposited ca. 720–820 million years ago. In contrast, diagenetic products of protosterols are widely distributed in older Proterozoic rocks and imply the presence of extinct proto-eukaryotes and/or sterol-producing bacteria before the evolution of crown-group eukaryotes.
β-sitosterol (beta-sitosterol) is one of several phytosterols with chemical structures similar to that of cholesterol. It is a white, waxy powder with a characteristic odor, and is one of the components of the food additive E499. Phytosterols are hydrophobic and soluble in alcohols.
The steroidogenic acute regulatory protein, commonly referred to as StAR (STARD1), is a transport protein that regulates cholesterol transfer within the mitochondria, which is the rate-limiting step in the production of steroid hormones. It is primarily present in steroid-producing cells, including theca cells and luteal cells in the ovary, Leydig cells in the testis and cell types in the adrenal cortex.
Cholestane is a saturated tetracyclic triterpene. 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. Cholesterol is made in low abundance by other organisms (e.g., rhodophytes, land plants), but because these other organisms produce a variety of sterols it cannot be used as a conclusive indicator of any one taxon. It is often found in analysis of organic compounds in petroleum.
Cholesterol 7 alpha-hydroxylase also known as cholesterol 7-alpha-monooxygenase or cytochrome P450 7A1 (CYP7A1) is an enzyme that in humans is encoded by the CYP7A1 gene which has an important role in cholesterol metabolism. It is a cytochrome P450 enzyme, which belongs to the oxidoreductase class, and converts cholesterol to 7-alpha-hydroxycholesterol, the first and rate limiting step in bile acid synthesis.
In enzymology, a Δ7-sterol 5(6)-desaturase is an enzyme that catalyzes the chemical reaction
Tomatine is a glycoalkaloid, found in the stems and leaves of tomato plants, and in the fruits at much lower concentrations. Chemically pure tomatine is a white crystalline solid at standard temperature and pressure.
CYP8B1 also known as sterol 12-alpha-hydroxylase is a protein which in humans is encoded by the CYP8B1 gene.
Desmosterol (Cholesta-5,24-dien-3β-ol) is a lipid present in the membrane of phytoplankton. Structurally, desmosterol has a similar backbone to cholesterol, with the exception of an additional double bond in the structure of desmosterol.
START is a lipid-binding domain in StAR, HD-ZIP and signalling proteins. The archetypical domain is found in StAR, a mitochondrial protein that is synthesized in steroid-producing cells. StAR initiates steroid production by mediating the delivery of cholesterol to the first enzyme in the steroidogenic pathway. The START domain is critical for this activity, perhaps through the binding of cholesterol. Following the discovery of StAR, 15 START-domain-containing proteins were subsequently identified in vertebrates as well as other that are related.
Cholesterol total synthesis in chemistry describes the total synthesis of the complex biomolecule cholesterol and is considered a great scientific achievement. The research group of Robert Robinson with John Cornforth published their synthesis in 1951 and that of Robert Burns Woodward with Franz Sondheimer in 1952. Both groups competed for the first publication since 1950 with Robinson having started in 1932 and Woodward in 1949. According to historian Greg Mulheirn the Robinson effort was hampered by his micromanagement style of leadership and the Woodward effort was greatly facilitated by his good relationships with chemical industry. Around 1949 steroids like cortisone were produced from natural resources but expensive. Chemical companies Merck & Co. and Monsanto saw commercial opportunities for steroid synthesis and not only funded Woodward but also provided him with large quantities of certain chemical intermediates from pilot plants. Hard work also helped the Woodward effort: one of the intermediate compounds was named Christmasterone as it was synthesized on Christmas Day 1950 by Sondheimer.
A steroidogenesis inhibitor, also known as a steroid biosynthesis inhibitor, is a type of drug which inhibits one or more of the enzymes that are involved in the process of steroidogenesis, the biosynthesis of endogenous steroids and steroid hormones. They may inhibit the production of cholesterol and other sterols, sex steroids such as androgens, estrogens, and progestogens, corticosteroids such as glucocorticoids and mineralocorticoids, and neurosteroids. They are used in the treatment of a variety of medical conditions that depend on endogenous steroids.
