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A steroid is a biologically active
organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...
with four rings arranged in a specific
molecular configuration The molecular configuration of a molecule is the ''permanent'' geometry that results from the spatial arrangement of its bonds. The ability of the same set of atoms to form two or more molecules with different configurations is stereoisomerism. ...
. Steroids have two principal biological functions: as important components of
cell membrane The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...
s that alter
membrane fluidity In biology, membrane fluidity refers to the viscosity of the lipid bilayer of a cell membrane or a synthetic lipid membrane. Lipid packing can influence the fluidity of the membrane. Viscosity of the membrane can affect the rotation and diffusion ...
; and as
signaling molecules In biology, cell signaling (cell signalling in British English) or cell communication is the ability of a cell to receive, process, and transmit signals with its environment and with itself. Cell signaling is a fundamental property of all cellula ...
. Hundreds of steroids are found in
plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclu ...
s,
animal Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...
s and
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
. All steroids are manufactured in cells from the sterols
lanosterol Lanosterol is a tetracyclic triterpenoid and is the compound from which all animal and fungal steroids are derived. By contrast plant steroids are produced via cycloartenol. Role in biosynthesis of other steroids Elaboration of lanosterol under en ...
(
opisthokonts The opisthokonts () are a broad group of eukaryotes, including both the animal and fungus kingdoms. The opisthokonts, previously called the "Fungi/Metazoa group", are generally recognized as a clade. Opisthokonts together with Apusomonadida and ...
) or cycloartenol (plants). Lanosterol and cycloartenol are derived from the
cyclization A cyclic compound (or ring compound) is a term for a compound in the field of chemistry in which one or more series of atoms in the compound is connected to form a ring. Rings may vary in size from three to many atoms, and include examples where ...
of the
triterpene Triterpenes are a class of chemical compounds composed of three terpene units with the molecular formula C30H48; they may also be thought of as consisting of six isoprene units. Animals, plants and fungi all produce triterpenes, including squa ...
squalene Squalene is an organic compound. It is a triterpenoid with the formula C30H50. It is a colourless oil, although impure samples appear yellow. It was originally obtained from shark liver oil (hence its name, as ''Squalus'' is a genus of sharks). A ...
. The steroid core structure is typically composed of seventeen
carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...
atoms, bonded in four " fused" rings: three six-member cyclohexane rings (rings A, B and C in the first illustration) and one five-member
cyclopentane Cyclopentane (also called C pentane) is a highly flammable alicyclic hydrocarbon with chemical formula C5H10 and CAS number 287-92-3, consisting of a ring of five carbon atoms each bonded with two hydrogen atoms above and below the plane. It occu ...
ring (the D ring). Steroids vary by the
functional groups In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest ...
attached to this four-ring core and by the
oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...
of the rings. Sterols are forms of steroids with a hydroxy group at position three and a skeleton derived from
cholestane 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 compo ...
. ''Also available with the same authors at'' ; ''Also available online at'' Steroids can also be more radically modified, such as by changes to the ring structure, for example,
cutting Cutting is the separation or opening of a physical object, into two or more portions, through the application of an acutely directed force. Implements commonly used for wikt:cut, cutting are the knife and saw, or in medicine and science the scal ...
one of the rings. Cutting Ring B produces
secosteroid A secosteroid () is a type of steroid with a "broken" ring. The word ''secosteroid ''derives from the Latin verb ''secare'' meaning "to cut", and 'steroid'. Secosteroids are alternatively described as a subclass of steroids; ; or derived from s ...
s one of which is vitamin D3. Examples include anabolic steroids, the
lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids includ ...
cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell mem ...
, the sex hormones
estradiol Estradiol (E2), also spelled oestradiol, is an estrogen steroid hormone and the major female sex hormone. It is involved in the regulation of the estrous and menstrual female reproductive cycles. Estradiol is responsible for the development o ...
and
testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristi ...
, and the
anti-inflammatory Anti-inflammatory is the property of a substance or treatment that reduces inflammation or swelling. Anti-inflammatory drugs, also called anti-inflammatories, make up about half of analgesics. These drugs remedy pain by reducing inflammation as o ...
drug
dexamethasone Dexamethasone is a glucocorticoid medication used to treat rheumatic problems, a number of skin diseases, severe allergies, asthma, chronic obstructive lung disease, croup, brain swelling, eye pain following eye surgery, superior vena ...
.


Nomenclature

Gonane Gonane is a chemical compound with formula , whose molecule can be described as three molecules or entities of cyclohexane and one of cyclopentane, fused in a particular way. More specifically, the molecule can be described as that of cyclohe ...
, also known as steran or cyclopentanoperhydrophenanthrene, the simplest steroid and the nucleus of all steroids and sterols, is composed of seventeen
carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...
atoms in carbon-carbon bonds forming four fused rings in a three-dimensional shape. The three cyclohexane rings (A, B, and C in the first illustration) form the skeleton of a perhydro derivative of phenanthrene. The D ring has a
cyclopentane Cyclopentane (also called C pentane) is a highly flammable alicyclic hydrocarbon with chemical formula C5H10 and CAS number 287-92-3, consisting of a ring of five carbon atoms each bonded with two hydrogen atoms above and below the plane. It occu ...
structure. When the two methyl groups and eight carbon
side chain In organic chemistry and biochemistry, a side chain is a chemical group that is attached to a core part of the molecule called the "main chain" or backbone. The side chain is a hydrocarbon branching element of a molecule that is attached to a ...
s (at C-17, as shown for cholesterol) are present, the steroid is said to have a cholestane framework. The two common 5α and 5β stereoisomeric forms of steroids exist because of differences in the side of the largely planar ring system where the hydrogen (H) atom at carbon-5 is attached, which results in a change in steroid A-ring conformation. Isomerisation at the C-21 side chain produces a parallel series of compounds, referred to as isosteroids. Examples of steroid structures are: File:Testosteron.svg, alt=Chemical diagram,
Testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristi ...
, the principal male
sex hormone Sex hormones, also known as sex steroids, gonadocorticoids and gonadal steroids, are steroid hormones that interact with vertebrate steroid hormone receptors. The sex hormones include the androgens, estrogens, and progestogens. Their effect ...
and an anabolic steroid File:Cholsäure.svg, alt=Chemical diagram,
Cholic acid Cholic acid, also known as 3α,7α,12α-trihydroxy-5β-cholan-24-oic acid is a primary bile acid that is insoluble in water (soluble in alcohol and acetic acid), it is a white crystalline substance. Salts of cholic acid are called cholates. Chol ...
, a bile acid, showing the carboxylic acid and additional hydroxyl groups often present File:Dexamethasone structure.svg, alt=Chemical diagram,
Dexamethasone Dexamethasone is a glucocorticoid medication used to treat rheumatic problems, a number of skin diseases, severe allergies, asthma, chronic obstructive lung disease, croup, brain swelling, eye pain following eye surgery, superior vena ...
, a synthetic corticosteroid drug File:Lanosterin.svg, alt=Chemical diagram,
Lanosterol Lanosterol is a tetracyclic triterpenoid and is the compound from which all animal and fungal steroids are derived. By contrast plant steroids are produced via cycloartenol. Role in biosynthesis of other steroids Elaboration of lanosterol under en ...
, the
biosynthetic Biosynthesis is a multi-step, enzyme-Catalysis, catalyzed process where substrate (chemistry), substrates are converted into more complex Product (chemistry), products in living organisms. In biosynthesis, simple Chemical compound, compounds are mo ...
precursor to animal steroids. The number of carbons (30) indicates its
triterpenoid Triterpenes are a class of chemical compounds composed of three terpene units with the molecular formula C30H48; they may also be thought of as consisting of six isoprene units. Animals, plants and fungi all produce triterpenes, including squal ...
classification. File:Progesteron.svg, alt=Chemical diagram, Progesterone, a steroid hormone involved in the female menstrual cycle, pregnancy, and embryogenesis File:Medrogestone.png, alt=Chemical diagram,
Medrogestone Medrogestone, sold under the brand name Colprone among others, is a progestin medication which has been used in menopausal hormone therapy and in the treatment of gynecological disorders. It is available both alone and in combination with an est ...
, a synthetic drug with effects similar to progesterone File:Sitosterol structure.svg, alt=Chemical diagram,
β-Sitosterol β-sitosterol (beta-sitosterol) is one of several phytosterols (plant sterols) 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 ...
, a plant or
phytosterol 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 phy ...
, with a fully branched hydrocarbon side chain at C-17 and an hydroxyl group at C-3
In addition to the ring scissions (cleavages), expansions and contractions (cleavage and reclosing to a larger or smaller rings)—all variations in the carbon-carbon bond framework—steroids can also vary: * in the bond orders within the rings, * in the number of methyl groups attached to the ring (and, when present, on the prominent side chain at C17), * in the functional groups attached to the rings and side chain, and * in the configuration of groups attached to the rings and chain. For instance, sterols such as cholesterol and lanosterol have a hydroxyl group attached at position C-3, while
testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristi ...
and progesterone have a carbonyl (oxo substituent) at C-3; of these,
lanosterol Lanosterol is a tetracyclic triterpenoid and is the compound from which all animal and fungal steroids are derived. By contrast plant steroids are produced via cycloartenol. Role in biosynthesis of other steroids Elaboration of lanosterol under en ...
alone has two methyl groups at C-4 and cholesterol (with a C-5 to C-6 double bond) differs from testosterone and progesterone (which have a C-4 to C-5 double bond).


Species distribution and function

In eukaryotes, steroids are found in fungi, animals, and plants.


Fungal steroids

Fungal steroids include the ergosterols, which are involved in maintaining the integrity of the fungal cellular membrane. Various antifungal drugs, such as
amphotericin B Amphotericin B is an antifungal medication used for serious mycosis, fungal infections and leishmaniasis. The fungal infections it is used to treat include mucormycosis, aspergillosis, blastomycosis, candida infections, candidiasis, coccidioidomy ...
and
azole antifungals Azoles are a class of five-membered heterocyclic compounds containing a nitrogen atom and at least one other non-carbon atom (i.e. nitrogen, sulfur, or oxygen) as part of the ring. Their names originate from the Hantzsch–Widman nomenclature. ...
, utilize this information to kill pathogenic fungi. Fungi can alter their ergosterol content (e.g. through loss of function mutations in the enzymes ERG3 or ERG6, inducing depletion of ergosterol, or mutations that decrease the ergosterol content) to develop resistance to drugs that target ergosterol. Ergosterol is analogous to the
cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell mem ...
found in the cellular membranes of animals (including humans), or the
phytosterols 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 phytos ...
found in the cellular membranes of plants. All mushrooms contain large quantities of ergosterol, in the range of tens to hundreds of milligrams per 100 grams of dry weight. Oxygen is necessary for the synthesis of ergosterol in fungi. Ergosterol is responsible for the
vitamin D Vitamin D is a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and many other biological effects. In humans, the most important compounds in this group are vitamin D3 (c ...
content found in mushrooms; ergosterol is chemically converted into provitamin D2 by exposure to
ultraviolet light Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...
. Provitamin D2 spontaneously forms vitamin D2. However, not all fungi utilize ergosterol in their cellular membranes; for example, the pathogenic fungal species ''
Pneumocystis jirovecii ''Pneumocystis jirovecii'' (previously ''P. carinii'') is a yeast-like fungus of the genus ''Pneumocystis''. The causative organism of ''Pneumocystis'' pneumonia, it is an important human pathogen, particularly among immunocompromised hosts. Pr ...
'' does not, which has important clinical implications (given the mechanism of action of many antifungal drugs). Using the fungus ''
Saccharomyces cerevisiae ''Saccharomyces cerevisiae'' () (brewer's yeast or baker's yeast) is a species of yeast (single-celled fungus microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have b ...
'' as an example, other major steroids include ergosta‐5,7,22,24(28)‐tetraen‐3β‐ol, zymosterol, and
lanosterol Lanosterol is a tetracyclic triterpenoid and is the compound from which all animal and fungal steroids are derived. By contrast plant steroids are produced via cycloartenol. Role in biosynthesis of other steroids Elaboration of lanosterol under en ...
. ''S. cerevisiae'' utilizes 5,6‐dihydroergosterol in place of ergosterol in its cell membrane.


Animal steroids

Animal steroids include compounds of
vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with c ...
and
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...
origin, the latter including
ecdysteroid Ecdysteroids are arthropod steroid hormones that are mainly responsible for molting, development and, to a lesser extent, reproduction; examples of ecdysteroids include ecdysone, ecdysterone, turkesterone and 2-deoxyecdysone. These compounds are ...
s such as
ecdysterone 20-Hydroxyecdysone (ecdysterone or 20E) is a naturally occurring ecdysteroid hormone which controls the ecdysis (moulting) and metamorphosis of arthropods. It is therefore one of the most common moulting hormones in insects, crabs, etc. It is als ...
(controlling molting in some species). Vertebrate examples include the
steroid hormones A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be grouped into two classes: corticosteroids (typically made in the adrenal cortex, hence ''cortico-'') and sex steroids (typically made in the gonads or placenta). Withi ...
and cholesterol; the latter is a structural component of cell membranes that helps determine the fluidity of cell membranes and is a principal constituent of
plaque Plaque may refer to: Commemorations or awards * Commemorative plaque, a plate or tablet fixed to a wall to mark an event, person, etc. * Memorial Plaque (medallion), issued to next-of-kin of dead British military personnel after World War I * Pl ...
(implicated in
atherosclerosis Atherosclerosis is a pattern of the disease arteriosclerosis in which the wall of the artery develops abnormalities, called lesions. These lesions may lead to narrowing due to the buildup of atheromatous plaque. At onset there are usually no s ...
). Steroid hormones include: *
Sex hormone Sex hormones, also known as sex steroids, gonadocorticoids and gonadal steroids, are steroid hormones that interact with vertebrate steroid hormone receptors. The sex hormones include the androgens, estrogens, and progestogens. Their effect ...
s, which influence sex differences and support reproduction. These include
androgen An androgen (from Greek ''andr-'', the stem of the word meaning "man") is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This in ...
s,
estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...
s, and progestogens. * Corticosteroids, including most synthetic steroid drugs, with natural product classes the
glucocorticoid Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every verteb ...
s (which regulate many aspects of
metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run c ...
and immune function) and the
mineralocorticoid Mineralocorticoids are a class of corticosteroids, which in turn are a class of steroid hormones. Mineralocorticoids are produced in the adrenal cortex and influence salt and water balances ( electrolyte balance and fluid balance). The primary ...
s (which help maintain blood volume and control
renal The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; bloo ...
excretion of electrolytes) * Anabolic steroids,
natural Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are ...
and synthetic, which interact with androgen receptors to increase muscle and bone synthesis. In popular use, the term "steroids" often refers to anabolic steroids.


Plant steroids

Plant steroids include steroidal
alkaloid Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar ...
s found in Solanaceae and
Melanthiaceae Melanthiaceae, also called the bunchflower family, is a family of flowering herbaceous perennial plants native to the Northern Hemisphere. Along with many other lilioid monocots, early authors considered members of this family to belong to t ...
(specially the genus
Veratrum ''Veratrum'' is a genus of flowering plants in the family Melanthiaceae. It occurs in damp habitats across much of temperate and subarctic Europe, Asia, and North America. ''Veratrum'' species are vigorous herbaceous perennials with highly poiso ...
),
cardiac glycoside Cardiac glycosides are a class of organic compounds that increase the output force of the heart and decrease its rate of contractions by inhibiting the cellular sodium-potassium ATPase pump. Their beneficial medical uses are as treatments for c ...
s, the
phytosterol 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 phy ...
s and the
brassinosteroid Brassinosteroids (BRs or less commonly BS) are a class of polyhydroxysteroids that have been recognized as a sixth class of plant hormones and may have utility as an anticancer drug for endocrine-responsive cancers to induce apoptosis and inhibit ...
s (which include several plant hormones).


Prokaryotes

In prokaryotes, biosynthetic pathways exist for the tetracyclic steroid framework (e.g. in mycobacteria) – where its origin from eukaryotes is conjectured – and the more-common pentacyclic triterpinoid
hopanoid Hopanoids are a diverse subclass of triterpenoids with the same hydrocarbon skeleton as the compound hopane. This group of pentacyclic molecules therefore refers to simple hopenes, hopanols and hopanes, but also to extensively functionalized deriv ...
framework.


Types


By function

The major classes of
steroid hormones A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be grouped into two classes: corticosteroids (typically made in the adrenal cortex, hence ''cortico-'') and sex steroids (typically made in the gonads or placenta). Withi ...
, with prominent members and examples of related functions, are: * Corticosteroids: **
Glucocorticoid Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every verteb ...
s: *** Cortisol, a
glucocorticoid Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every verteb ...
whose functions include
immunosuppression Immunosuppression is a reduction of the activation or efficacy of the immune system. Some portions of the immune system itself have immunosuppressive effects on other parts of the immune system, and immunosuppression may occur as an adverse reacti ...
**
Mineralocorticoid Mineralocorticoids are a class of corticosteroids, which in turn are a class of steroid hormones. Mineralocorticoids are produced in the adrenal cortex and influence salt and water balances ( electrolyte balance and fluid balance). The primary ...
s: *** Aldosterone, a
mineralocorticoid Mineralocorticoids are a class of corticosteroids, which in turn are a class of steroid hormones. Mineralocorticoids are produced in the adrenal cortex and influence salt and water balances ( electrolyte balance and fluid balance). The primary ...
that helps regulate blood pressure through water and electrolyte balance * Sex steroids: ** Progestogens: *** Progesterone, which regulates cyclical changes in the endometrium of the
uterus The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The ...
and maintains a
pregnancy Pregnancy is the time during which one or more offspring develops (gestation, gestates) inside a woman, woman's uterus (womb). A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occur ...
**
Androgens An androgen (from Greek ''andr-'', the stem of the word meaning "man") is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This in ...
: ***
Testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristi ...
, which contributes to the development and maintenance of male
secondary sex characteristic Secondary sex characteristics are features that appear during puberty in humans, and at sexual maturity in other animals. These characteristics are particularly evident in the sexually dimorphic phenotypic traits that distinguish the sexes of a s ...
s **
Estrogens Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal acti ...
: ***
Estradiol Estradiol (E2), also spelled oestradiol, is an estrogen steroid hormone and the major female sex hormone. It is involved in the regulation of the estrous and menstrual female reproductive cycles. Estradiol is responsible for the development o ...
, which contributes to the development and maintenance of female secondary sex characteristics Additional classes of steroids include: * Neurosteroids such as and allopregnanolone * Bile acids such as
taurocholic acid Taurocholic acid, known also as cholaic acid, cholyltaurine, or acidum cholatauricum, is a deliquescent yellowish crystalline bile acid involved in the emulsification of fats. It occurs as a sodium salt in the bile of mammals. It is a conjugat ...
*
Aminosteroid Aminosteroids are a group of steroids with a similar structure based on an amino-substituted steroid nucleus. They are neuromuscular blocking agents, acting as competitive antagonists of the nicotinic acetylcholine receptor (nAChR), and block th ...
neuromuscular blocking agent Neuromuscular-blocking drugs block neuromuscular transmission at the neuromuscular junction, causing paralysis of the affected skeletal muscles. This is accomplished via their action on the post-synaptic acetylcholine (Nm) receptors. In clin ...
s (mainly synthetic) such as
pancuronium bromide Pancuronium (trademarked as Pavulon) is an aminosteroid muscle relaxant with various medical uses. It is used in euthanasia and is used in some states as the second of three drugs administered during lethal injections in the United States. Mecha ...
* Steroidal antiandrogens (mainly synthetic) such as
cyproterone acetate Cyproterone acetate (CPA), sold alone under the brand name Androcur or with ethinylestradiol under the brand names Diane or Diane-35 among others, is an antiandrogen and progestin medication used in the treatment of androgen-dependent condition ...
*
Steroidogenesis inhibitor 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 hor ...
s (mainly exogenous) such as alfatradiol * Membrane sterols such as
cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell mem ...
, ergosterol, and various
phytosterol 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 phy ...
s * Toxins such as steroidal saponins and
cardenolide A cardenolide is a type of steroid. Many plants contain derivatives, collectively known as cardenolides, including many in the form of cardenolide glycosides (cardenolides that contain structural groups derived from sugars). Cardenolide glycoside ...
s/
cardiac glycoside Cardiac glycosides are a class of organic compounds that increase the output force of the heart and decrease its rate of contractions by inhibiting the cellular sodium-potassium ATPase pump. Their beneficial medical uses are as treatments for c ...
s As well as the following class of
secosteroid A secosteroid () is a type of steroid with a "broken" ring. The word ''secosteroid ''derives from the Latin verb ''secare'' meaning "to cut", and 'steroid'. Secosteroids are alternatively described as a subclass of steroids; ; or derived from s ...
s (open-ring steroids): *
Vitamin D Vitamin D is a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and many other biological effects. In humans, the most important compounds in this group are vitamin D3 (c ...
forms such as
ergocalciferol Ergocalciferol, also known as vitamin D2 and nonspecifically calciferol, is a type of vitamin D found in food and used as a dietary supplement. As a supplement it is used to prevent and treat vitamin D deficiency. This includes vitamin D defici ...
,
cholecalciferol Cholecalciferol, also known as vitamin D3 and colecalciferol, is a type of vitamin D that is made by the skin when exposed to sunlight; it is found in some foods and can be taken as a dietary supplement. Cholecalciferol is made in the skin fo ...
, and
calcitriol Calcitriol is the active form of vitamin D, normally made in the kidney. It is also known as 1,25-dihydroxycholecalciferol. It is a hormone which binds to and activates the vitamin D receptor in the nucleus of the cell, which then increases the ...


By structure


Intact ring system

Steroids can be classified based on their chemical composition. One example of how
MeSH A mesh is a barrier made of connected strands of metal, fiber, or other flexible or ductile materials. A mesh is similar to a web or a net in that it has many attached or woven strands. Types * A plastic mesh may be extruded, oriented, exp ...
performs this classification is available at the Wikipedia MeSH catalog. Examples of this classification include: In biology, it is common to name the above steroid classes by the number of carbon atoms present when referring to hormones: C18-steroids for the estranes (mostly estrogens), C19-steroids for the androstanes (mostly androgens), and C21-steroids for the pregnanes (mostly corticosteroids). The classification "
17-ketosteroid 150px, Androstenedione 150px, Androsterone 150px, Estrone A ketosteroid, or an oxosteroid, is a steroid in which a hydrogen atom has been replaced with a ketone (C=O) group. A 17-ketosteroid is a ketosteroid in which the ketone is located s ...
" is also important in medicine. The gonane (steroid nucleus) is the parent 17-carbon tetracyclic hydrocarbon molecule with no
alkyl In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cycloa ...
sidechains.


Cleaved, contracted, and expanded rings

Secosteroids (Latin ''seco'', "to cut") are a subclass of steroidal compounds resulting, biosynthetically or conceptually, from scission (cleavage) of parent steroid rings (generally one of the four). Major secosteroid subclasses are defined by the steroid carbon atoms where this scission has taken place. For instance, the prototypical secosteroid
cholecalciferol Cholecalciferol, also known as vitamin D3 and colecalciferol, is a type of vitamin D that is made by the skin when exposed to sunlight; it is found in some foods and can be taken as a dietary supplement. Cholecalciferol is made in the skin fo ...
, vitamin D3 (shown), is in the 9,10-secosteroid subclass and derives from the cleavage of carbon atoms C-9 and C-10 of the steroid B-ring; 5,6-secosteroids and 13,14-steroids are similar. Norsteroids (
nor- In chemical nomenclature, nor- is a prefix to name a structural analog that can be derived from a parent compound by the removal of one carbon atom along with the accompanying hydrogen atoms. The nor-compound can be derived by removal of a , , or C ...
, L. ''norma''; "normal" in chemistry, indicating carbon removal) and homosteroids (homo-, Greek ''homos''; "same", indicating carbon addition) are structural subclasses of steroids formed from biosynthetic steps. The former involves enzymic ring expansion-contraction reactions, and the latter is accomplished ( biomimetically) or (more frequently) through
ring closure A cyclic compound (or ring compound) is a term for a compound in the field of chemistry in which one or more series of atoms in the compound is connected to form a ring. Rings may vary in size from three to many atoms, and include examples where ...
s of acyclic precursors with more (or fewer) ring atoms than the parent steroid framework. Combinations of these ring alterations are known in nature. For instance, ewes who graze on corn lily ingest
cyclopamine Cyclopamine (11-deoxojervine) is a naturally occurring chemical that belongs in the family of steroidal alkaloids. It is a teratogen isolated from the corn lily ('' Veratrum californicum'') that causes fatal birth defects. It prevents the embryo ...
(shown) and veratramine, two of a sub-family of steroids where the C- and D-rings are contracted and expanded respectively via a
biosynthetic Biosynthesis is a multi-step, enzyme-Catalysis, catalyzed process where substrate (chemistry), substrates are converted into more complex Product (chemistry), products in living organisms. In biosynthesis, simple Chemical compound, compounds are mo ...
migration of the original C-13 atom. Ingestion of these C-nor-D-homosteroids results in birth defects in lambs:
cyclopia Cyclopia (named after the Greek mythology character cyclopes) is the most extreme form of holoprosencephaly and is a congenital disorder (birth defect) characterized by the failure of the embryonic prosencephalon to properly divide the orbits of ...
from
cyclopamine Cyclopamine (11-deoxojervine) is a naturally occurring chemical that belongs in the family of steroidal alkaloids. It is a teratogen isolated from the corn lily ('' Veratrum californicum'') that causes fatal birth defects. It prevents the embryo ...
and leg deformity from veratramine. A further C-nor-D-homosteroid (nakiterpiosin) is excreted by
Okinawa is a prefecture of Japan. Okinawa Prefecture is the southernmost and westernmost prefecture of Japan, has a population of 1,457,162 (as of 2 February 2020) and a geographic area of 2,281 km2 (880 sq mi). Naha is the capital and largest city ...
n cyanobacteriosponges. e.g., '' Terpios hoshinota'', leading to coral mortality from black coral disease. Nakiterpiosin-type steroids are active against the signaling pathway involving the
smoothened Smoothened is a protein that in humans is encoded by the SMO gene. Smoothened is a Class Frizzled (Class F) G protein-coupled receptor that is a component of the hedgehog signaling pathway and is conserved from flies to humans. It is the molecula ...
and
hedgehog A hedgehog is a spiny mammal of the subfamily Erinaceinae, in the eulipotyphlan family Erinaceidae. There are seventeen species of hedgehog in five genera found throughout parts of Europe, Asia, and Africa, and in New Zealand by introductio ...
proteins, a pathway which is hyperactive in a number of cancers.


Biological significance

Steroids and their metabolites often function as
signalling In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The ''IEEE Transactions on Signal Processing'' ...
molecules (the most notable examples are steroid hormones), and steroids and phospholipids are components of
cell membrane The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...
s. Steroids such as cholesterol decrease
membrane fluidity In biology, membrane fluidity refers to the viscosity of the lipid bilayer of a cell membrane or a synthetic lipid membrane. Lipid packing can influence the fluidity of the membrane. Viscosity of the membrane can affect the rotation and diffusion ...
. Similar to
lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids includ ...
s, steroids are highly concentrated energy stores. However, they are not typically sources of energy; in mammals, they are normally metabolized and excreted. Steroids play critical roles in a number of disorders, including malignancies like prostate cancer, where steroid production inside and outside the tumour promotes cancer cell aggressiveness.


Biosynthesis and metabolism

The hundreds of steroids found in animals, fungi, and
plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclu ...
s are made from
lanosterol Lanosterol is a tetracyclic triterpenoid and is the compound from which all animal and fungal steroids are derived. By contrast plant steroids are produced via cycloartenol. Role in biosynthesis of other steroids Elaboration of lanosterol under en ...
(in animals and fungi; see examples above) or cycloartenol (in other eukaryotes). Both lanosterol and cycloartenol derive from
cyclization A cyclic compound (or ring compound) is a term for a compound in the field of chemistry in which one or more series of atoms in the compound is connected to form a ring. Rings may vary in size from three to many atoms, and include examples where ...
of the
triterpenoid Triterpenes are a class of chemical compounds composed of three terpene units with the molecular formula C30H48; they may also be thought of as consisting of six isoprene units. Animals, plants and fungi all produce triterpenes, including squal ...
squalene Squalene is an organic compound. It is a triterpenoid with the formula C30H50. It is a colourless oil, although impure samples appear yellow. It was originally obtained from shark liver oil (hence its name, as ''Squalus'' is a genus of sharks). A ...
. Lanosterol and cycloartenol are sometimes called protosterols because they serve as the starting compounds for all other steroids. Steroid biosynthesis is an
anabolic Anabolism () is the set of metabolic pathways that construct molecules from smaller units. These reactions require energy, known also as an endergonic process. Anabolism is the building-up aspect of metabolism, whereas catabolism is the breaking ...
pathway which produces steroids from simple precursors. A unique biosynthetic pathway is followed in animals (compared to many other
organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...
s), making the pathway a common target for antibiotics and other anti-infection drugs. Steroid metabolism in humans is also the target of cholesterol-lowering drugs, such as
statin Statins, also known as HMG-CoA reductase inhibitors, are a class of lipid-lowering medications that reduce illness and mortality in those who are at high risk of cardiovascular disease. They are the most common cholesterol-lowering drugs. Low ...
s. In humans and other animals the biosynthesis of steroids follows the mevalonate pathway, which uses acetyl-CoA as building blocks for dimethylallyl diphosphate (DMAPP) and isopentenyl diphosphate (IPP). In subsequent steps DMAPP and IPP conjugate to form farnesyl diphosphate (FPP), which further conjugates with each other to form the linear triterpenoid squalene. Squalene biosynthesis is catalyzed by squalene synthase, which belongs to the squalene/phytoene synthase family. Subsequent
epoxidation In organic chemistry, an epoxide is a cyclic ether () with a three-atom ring. This ring approximates an equilateral triangle, which makes it strained, and hence highly reactive, more so than other ethers. They are produced on a large scale ...
and cyclization of squalene generate lanosterol, which is the starting point for additional modifications into other steroids (steroidogenesis). In other eukaryotes, the cyclization product of epoxidized squalene (oxidosqualene) is cycloartenol.


Mevalonate pathway

The mevalonate pathway (also called HMG-CoA reductase pathway) begins with acetyl-CoA and ends with dimethylallyl diphosphate (DMAPP) and isopentenyl diphosphate (IPP). DMAPP and IPP donate isoprene units, which are assembled and modified to form
terpene Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes ...
s and isoprenoids (a large class of lipids, which include the carotenoids and form the largest class of plant natural products. Here, the isoprene units are joined to make
squalene Squalene is an organic compound. It is a triterpenoid with the formula C30H50. It is a colourless oil, although impure samples appear yellow. It was originally obtained from shark liver oil (hence its name, as ''Squalus'' is a genus of sharks). A ...
and folded into a set of rings to make
lanosterol Lanosterol is a tetracyclic triterpenoid and is the compound from which all animal and fungal steroids are derived. By contrast plant steroids are produced via cycloartenol. Role in biosynthesis of other steroids Elaboration of lanosterol under en ...
. Lanosterol can then be converted into other steroids, such as cholesterol and ergosterol. Two classes of drugs target the
mevalonate pathway The mevalonate pathway, also known as the isoprenoid pathway or HMG-CoA reductase pathway is an essential metabolic pathway present in eukaryotes, archaea, and some bacteria. The pathway produces two five-carbon building blocks called isopentenyl ...
:
statin Statins, also known as HMG-CoA reductase inhibitors, are a class of lipid-lowering medications that reduce illness and mortality in those who are at high risk of cardiovascular disease. They are the most common cholesterol-lowering drugs. Low ...
s (like
rosuvastatin Rosuvastatin, sold under the brand name Crestor among others, is a statin medication, used to prevent cardiovascular disease in those at high risk and treat abnormal lipids. It is recommended to be used together with dietary changes, exercise, ...
), which are used to reduce elevated cholesterol levels, and
bisphosphonate Bisphosphonates are a class of drugs that prevent the loss of bone density, used to treat osteoporosis and similar diseases. They are the most commonly prescribed drugs used to treat osteoporosis. They are called bisphosphonates because they ...
s (like
zoledronate Zoledronic acid, also known as zoledronate and sold under the brand name Zometa by Novartis among others, is a medication used to treat a number of bone diseases. These include osteoporosis, high blood calcium due to cancer, bone breakdown due ...
), which are used to treat a number of bone-degenerative diseases.


Steroidogenesis

Steroidogenesis is the biological process by which steroids are generated from cholesterol and changed into other steroids. The pathways of steroidogenesis differ among species. The major classes of steroid hormones, as noted above (with their prominent members and functions), are the progestogens, corticosteroids (corticoids),
androgen An androgen (from Greek ''andr-'', the stem of the word meaning "man") is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This in ...
s, and
estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...
s. Human steroidogenesis of these classes occurs in a number of locations: *Progestogens are the precursors of all other human steroids, and all human tissues which produce steroids must first convert cholesterol to
pregnenolone Pregnenolone (P5), or pregn-5-en-3β-ol-20-one, is an endogenous steroid and precursor/ metabolic intermediate in the biosynthesis of most of the steroid hormones, including the progestogens, androgens, estrogens, glucocorticoids, and mineraloc ...
. This conversion is the rate-limiting step of steroid synthesis, which occurs inside the mitochondrion of the respective tissue. *Cortisol, corticosterone, aldosterone, and testosterone are produced in the adrenal cortex. *Estradiol, estrone and progesterone are made primarily in the ovary, estriol in
placenta The placenta is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate mate ...
during pregnancy, and
testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristi ...
primarily in the
testes A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoste ...
(some testosterone is also produced in the adrenal cortex). *Estradiol is converted from testosterone directly (in males), or via the primary pathway DHEA - androstenedione - estrone and secondarily via testosterone (in females). * Stromal cells have been shown to produce steroids in response to signaling produced by androgen-starved prostate cancer cells. *Some neurons and
glia Glia, also called glial cells (gliocytes) or neuroglia, are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system that do not produce electrical impulses. They maintain homeostasis, form myel ...
in the
central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...
(CNS) express the enzymes required for the local synthesis of pregnenolone, progesterone, DHEA and DHEAS, ''de novo'' or from peripheral sources.


Alternative pathways

In plants and bacteria, the non-mevalonate pathway (MEP pathway) uses pyruvate and
glyceraldehyde 3-phosphate Glyceraldehyde 3-phosphate, also known as triose phosphate or 3-phosphoglyceraldehyde and abbreviated as G3P, GA3P, GADP, GAP, TP, GALP or PGAL, is a metabolite that occurs as an intermediate in several central pathways of all organisms.Nelson, D ...
as substrates to produce IPP and DMAPP. During diseases pathways otherwise not significant in healthy humans can become utilized. For example, in one form of
congenital adrenal hyperplasia Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders characterized by impaired cortisol synthesis. It results from the deficiency of one of the five enzymes required for the synthesis of cortisol in the adrenal cort ...
a deficiency in the 21-hydroxylase enzymatic pathway leads to an excess of
17α-Hydroxyprogesterone 17α-Hydroxyprogesterone (17α-OHP), also known as 17-OH progesterone (17-OHP), or hydroxyprogesterone (OHP), is an endogenous progestogen steroid hormone related to progesterone. It is also a chemical intermediate in the biosynthesis of many o ...
(17-OHP) – this pathological excess of 17-OHP in turn may be converted to
dihydrotestosterone Dihydrotestosterone (DHT, 5α-dihydrotestosterone, 5α-DHT, androstanolone or stanolone) is an endogenous androgen sex steroid and hormone. The enzyme 5α-reductase catalyzes the formation of DHT from testosterone in certain tissues includ ...
(DHT, a potent androgen) through among others 17,20 Lyase (a member of the
cytochrome P450 Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various co ...
family of enzymes), 5α-Reductase and 3α-Hydroxysteroid dehydrogenase.


Catabolism and excretion

Steroids are primarily oxidized by
cytochrome P450 oxidase Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compo ...
enzymes, such as CYP3A4. These reactions introduce oxygen into the steroid ring, allowing the cholesterol to be broken up by other enzymes into bile acids. These acids can then be eliminated by secretion from the
liver The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it ...
in bile. The expression of the
oxidase In biochemistry, an oxidase is an enzyme that catalyzes oxidation-reduction reactions, especially one involving dioxygen (O2) as the electron acceptor. In reactions involving donation of a hydrogen atom, oxygen is reduced to water (H2O) or hydro ...
gene can be
upregulated In the biological context of organisms' production of gene products, downregulation is the process by which a cell decreases the quantity of a cellular component, such as RNA or protein, in response to an external stimulus. The complementary pro ...
by the steroid sensor PXR when there is a high blood concentration of steroids. Steroid hormones, lacking the side chain of cholesterol and bile acids, are typically hydroxylated at various ring positions or oxidized at the 17 position, conjugated with sulfate or glucuronic acid and excreted in the urine.


Isolation, structure determination, and methods of analysis

Steroid ''isolation'', depending on context, is the isolation of chemical matter required for
chemical structure A chemical structure determination includes a chemist's specifying the molecular geometry and, when feasible and necessary, the electronic structure of the target molecule or other solid. Molecular geometry refers to the spatial arrangement of ...
elucidation, derivitzation or degradation chemistry, biological testing, and other research needs (generally milligrams to grams, but often more or the isolation of "analytical quantities" of the substance of interest (where the focus is on identifying and quantifying the substance (for example, in biological tissue or fluid). The amount isolated depends on the analytical method, but is generally less than one microgram. The methods of isolation to achieve the two scales of product are distinct, but include extraction, precipitation,
adsorption Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which ...
,
chromatography In chemical analysis, chromatography is a laboratory technique for the separation of a mixture into its components. The mixture is dissolved in a fluid solvent (gas or liquid) called the ''mobile phase'', which carries it through a system ( ...
, and crystallization. In both cases, the isolated substance is purified to chemical homogeneity; combined separation and analytical methods, such as LC-MS, are chosen to be "orthogonal"—achieving their separations based on distinct modes of interaction between substance and isolating matrix—to detect a single species in the pure sample. ''Structure determination'' refers to the methods to determine the chemical structure of an isolated pure steroid, using an evolving array of chemical and physical methods which have included
NMR Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are perturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electromagnetic signal with ...
and small-molecule crystallography. ''Methods of analysis'' overlap both of the above areas, emphasizing analytical methods to determining if a steroid is present in a mixture and determining its quantity.


Chemical synthesis

Microbial catabolism of
phytosterol 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 phy ...
side chain In organic chemistry and biochemistry, a side chain is a chemical group that is attached to a core part of the molecule called the "main chain" or backbone. The side chain is a hydrocarbon branching element of a molecule that is attached to a ...
s yields C-19 steroids, C-22 steroids, and
17-ketosteroid 150px, Androstenedione 150px, Androsterone 150px, Estrone A ketosteroid, or an oxosteroid, is a steroid in which a hydrogen atom has been replaced with a ketone (C=O) group. A 17-ketosteroid is a ketosteroid in which the ketone is located s ...
s (i.e.
precursor Precursor or Precursors may refer to: * Precursor (religion), a forerunner, predecessor ** The Precursor, John the Baptist Science and technology * Precursor (bird), a hypothesized genus of fossil birds that was composed of fossilized parts of u ...
s to
adrenocortical hormone In humans and other animals, the adrenocortical hormones are hormones produced by the adrenal cortex, the outer region of the adrenal gland. These polycyclic steroid hormones have a variety of roles that are crucial for the body’s response to stre ...
s and contraceptives). The addition and modification of
functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the re ...
s is key when producing the wide variety of medications available within this chemical classification. These modifications are performed using conventional organic synthesis and/or
biotransformation Biotransformation is the biochemical modification of one chemical compound or a mixture of chemical compounds. Biotransformations can be conducted with whole cells, their lysates, or purified enzymes. Increasingly, biotransformations are effected w ...
techniques.


Precursors


Semisynthesis

The
semisynthesis Semisynthesis, or partial chemical synthesis, is a type of chemical synthesis that uses chemical compounds isolated from natural sources (such as microbial cell cultures or plant material) as the starting materials to produce novel compounds with ...
of steroids often begins from precursors such as
cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell mem ...
,
phytosterol 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 phy ...
s, or
sapogenin Sapogenins are the aglycones, or non-saccharide, portions of the family of natural products known as saponins. Sapogenins contain steroid or other triterpene frameworks as their key organic feature. For example, steroidal sapogenins such as tigge ...
s. The efforts of Syntex, a company involved in the
Mexican barbasco trade The Mexican barbasco trade was the trade of the diosgenin-rich yam species '' Dioscorea mexicana'', ''Dioscorea floribunda'' and ''Dioscorea composita'' which emerged in Mexico in the 1950s as part of the Mexican steroid industry. The trade consi ...
, used ''
Dioscorea mexicana ''Dioscorea mexicana'', Mexican yam or ''cabeza de negro'' is a species of yam in the genus ''Dioscorea''. ''Dioscorea mexicana'' is a caudiciform dioscorea having either a partly to completely above-ground dome-shaped caudex with a thick, ...
'' to produce the sapogenin diosgenin in the early days of the synthetic steroid
pharmaceutical industry The pharmaceutical industry discovers, develops, produces, and markets drugs or pharmaceutical drugs for use as medications to be administered to patients (or self-administered), with the aim to cure them, vaccinate them, or alleviate symptoms. ...
.


Total synthesis

Some steroidal hormones are economically obtained only by
total synthesis Total synthesis is the complete chemical synthesis of a complex molecule, often a natural product, from simple, commercially-available precursors. It usually refers to a process not involving the aid of biological processes, which distinguishes i ...
from
petrochemical Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable so ...
s (e.g. 13-
alkyl In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cycloa ...
steroids). For example, the pharmaceutical Norgestrel begins from
methoxy In organic chemistry, a methoxy group is the functional group consisting of a methyl group bound to oxygen. This alkoxy group has the formula . On a benzene ring, the Hammett equation classifies a methoxy substituent at the ''para'' position a ...
-
1-tetralone 1-Tetralone is a bicyclic aromatic hydrocarbon and a ketone. In terms of its structure, it can also be regarded as benzo-fused cyclohexanone. It is a colorless oil with a faint odor. It is used as starting material for agricultural and pharmace ...
, a petrochemical derived from
phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it ...
.


Research awards

A number of
Nobel Prize The Nobel Prizes ( ; sv, Nobelpriset ; no, Nobelprisen ) are five separate prizes that, according to Alfred Nobel's will of 1895, are awarded to "those who, during the preceding year, have conferred the greatest benefit to humankind." Alfr ...
s have been awarded for steroid research, including: * 1927 ( Chemistry)
Heinrich Otto Wieland Heinrich Otto Wieland (; 4 June 1877 – 5 August 1957) was a German chemist. He won the 1927 Nobel Prize in Chemistry for his research into the bile acids. Career In 1901 Wieland received his doctorate at the University of Munich while studyi ...
— Constitution of bile acids and sterols and their connection to vitamins * 1928 (Chemistry)
Adolf Otto Reinhold Windaus Adolf Otto Reinhold Windaus (; 25 December 1876 – 9 June 1959) 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 ...
— Constitution of sterols and their connection to vitamins * 1939 (Chemistry)
Adolf Butenandt Adolf Friedrich Johann Butenandt (; 24 March 1903 – 18 January 1995) was a German biochemist. He was awarded the Nobel Prize in Chemistry in 1939 for his "work on sex hormones." He initially rejected the award in accordance with government po ...
and
Leopold Ružička Leopold Ružička (; born Lavoslav Stjepan Ružička; 13 September 1887 – 26 September 1976) was a Croatian-Swiss scientist and joint winner of the 1939 Nobel Prize in Chemistry "for his work on polymethylenes and higher terpenes" "including t ...
— Isolation and structural studies of steroid sex hormones, and related studies on higher
terpene Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes ...
s * 1950 (
Physiology or Medicine The Nobel Prize in Physiology or Medicine is awarded yearly by the Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or medicine. The Nobel Prize is not a single prize, but five separate prizes that, according ...
)
Edward Calvin Kendall Edward Calvin Kendall (March 8, 1886 – May 4, 1972) was an American chemist. In 1950, Kendall was awarded the Nobel Prize for Physiology or Medicine along with Swiss chemist Tadeusz Reichstein and Mayo Clinic physician Philip S. Hench, for the ...
,
Tadeus Reichstein Tadeusz Reichstein (20 July 1897 – 1 August 1996) was a Polish-Swiss chemist and the Nobel Prize in Physiology or Medicine laureate (1950), which was awarded for his work on the isolation of cortisone. Early life Reichstein was born into a Po ...
, and
Philip Hench Philip Showalter Hench (February 28, 1896 – March 30, 1965) was an American physician. Hench, along with his Mayo Clinic co-worker Edward Calvin Kendall and Swiss chemist Tadeus Reichstein was awarded the Nobel Prize for Physiology or Medicine ...
— Structure and biological effects of adrenal hormones * 1965 (Chemistry)
Robert Burns Woodward Robert Burns Woodward (April 10, 1917 – July 8, 1979) was an American organic chemist. He is considered by many to be the most preeminent synthetic organic chemist of the twentieth century, having made many key contributions to the subject, e ...
— In part, for the synthesis of cholesterol,
cortisone Cortisone is a pregnene (21-carbon) steroid hormone. It is a naturally-occurring corticosteroid metabolite that is also used as a pharmaceutical prodrug; it is not synthesized in the adrenal glands. Cortisol is converted by the action of the enz ...
, and
lanosterol Lanosterol is a tetracyclic triterpenoid and is the compound from which all animal and fungal steroids are derived. By contrast plant steroids are produced via cycloartenol. Role in biosynthesis of other steroids Elaboration of lanosterol under en ...
* 1969 (Chemistry)
Derek Barton Sir Derek Harold Richard Barton (8 September 1918 – 16 March 1998) was an English organic chemist and Nobel Prize laureate for 1969. Education and early life Barton was born in Gravesend, Kent, to William Thomas and Maude Henrietta Barton ( ...
and
Odd Hassel Odd Hassel (17 May 1897 – 11 May 1981) was a Norwegian physical chemist and Nobel Laureate. Biography Hassel was born in Kristiania (now Oslo), Norway. His parents were Ernst Hassel (1848–1905), a gynaecologist, and Mathilde Klaveness ( ...
— Development of the concept of conformation in chemistry, emphasizing the steroid nucleus * 1975 (Chemistry)
Vladimir Prelog Vladimir Prelog (23 July 1906 – 7 January 1998) was a Croatian-Swiss organic chemist who received the 1975 Nobel Prize in chemistry for his research into the stereochemistry of organic molecules and reactions. Prelog was born and grew up in ...
— In part, for developing methods to determine the stereochemical course of cholesterol biosynthesis from mevalonic acid via
squalene Squalene is an organic compound. It is a triterpenoid with the formula C30H50. It is a colourless oil, although impure samples appear yellow. It was originally obtained from shark liver oil (hence its name, as ''Squalus'' is a genus of sharks). A ...


See also

*
Adrenal gland The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer cortex whic ...
*
Batrachotoxin Batrachotoxin (BTX) is an extremely potent cardio- and neurotoxic steroidal alkaloid found in certain species of beetles, birds, and frogs. The name is from the Greek word grc, βάτραχος, bátrachos, frog, label=none. Structurally-relate ...
* List of steroid abbreviations * List of steroids *
Membrane steroid receptor Membrane steroid receptors (mSRs), also called extranuclear steroid receptors, are a class of cell surface receptors activated by endogenous steroids that mediate rapid, non-genomic signaling via modulation of intracellular signaling cascades. mSR ...
*
Pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
*
Reverse cholesterol transport Reverse cholesterol transport is a multi-step process resulting in the net movement of cholesterol from peripheral tissues back to the liver first via entering the lymphatic system, then the bloodstream. Cholesterol from non-hepatic peripheral ti ...
*
Steroidogenesis inhibitor 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 hor ...
* Steroidogenic acute regulatory protein *
Steroidogenic enzyme __NOTOC__ Steroidogenic enzymes are enzymes that are involved in steroidogenesis and steroid biosynthesis. They are responsible for the biosynthesis of the steroid hormones, including sex steroids (androgens, estrogens, and progestogens) and cortic ...


References


Bibliography

* * * A concise history of the study of steroids. * A review of the history of steroid synthesis, especially
biomimetic Biomimetics or biomimicry is the emulation of the models, systems, and elements of nature for the purpose of solving complex human problems. The terms "biomimetics" and "biomimicry" are derived from grc, βίος (''bios''), life, and μίμησ ...
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