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A steroid is a terpenoid
Terpenoid

The terpenoids , sometimes called isoprenoids, are a large and diverse class of naturally-occurring organic compound similar to terpenes, derived from five-carbon isoprene units assembled and modified in thousands of ways....
 lipid
Lipid

Lipids are broadly defined as any fat-soluble , naturally-occurring molecule, such as fats, oils, waxes, cholesterol, sterols, fat-soluble vitamins , monoglycerides, diglycerides, phospholipids, and others....
 characterized by a carbon
Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
 skeleton with four fused rings, generally arranged in a 6-6-6-5 fashion. Steroids vary by the functional group
Functional group

In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules....
s attached to these rings and the oxidation state of the rings. Hundreds of distinct steroids are found in plant
Plant

Plants are Life organisms belonging to the Kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae....
s, animal
Animal

Animals are a major group of multicellular, eukaryotic organisms of the Kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life....
s, and fungi
Fungus

A fungus is a Eukaryote organism that is a member of the Kingdom Fungi . The fungi are a monophyletic group, also called the Eumycota , that is phylogeny distinct from the morphologically similar slime molds and water molds ....
.






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Lanosterol Skeletal
A steroid is a terpenoid
Terpenoid

The terpenoids , sometimes called isoprenoids, are a large and diverse class of naturally-occurring organic compound similar to terpenes, derived from five-carbon isoprene units assembled and modified in thousands of ways....
 lipid
Lipid

Lipids are broadly defined as any fat-soluble , naturally-occurring molecule, such as fats, oils, waxes, cholesterol, sterols, fat-soluble vitamins , monoglycerides, diglycerides, phospholipids, and others....
 characterized by a carbon
Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
 skeleton with four fused rings, generally arranged in a 6-6-6-5 fashion. Steroids vary by the functional group
Functional group

In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules....
s attached to these rings and the oxidation state of the rings. Hundreds of distinct steroids are found in plant
Plant

Plants are Life organisms belonging to the Kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae....
s, animal
Animal

Animals are a major group of multicellular, eukaryotic organisms of the Kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life....
s, and fungi
Fungus

A fungus is a Eukaryote organism that is a member of the Kingdom Fungi . The fungi are a monophyletic group, also called the Eumycota , that is phylogeny distinct from the morphologically similar slime molds and water molds ....
. All steroids are made in cells either from the sterol
Sterol

Sterols are an important class of organic molecules. They occur naturally in plants, animals and fungi, with the most familiar type of animal sterol being cholesterol, which has been shown to contribute to high blood pressure and heart disease....
 lanosterol
Lanosterol

Lanosterol is a tetracyclic terpene, which is the compound from which all steroids are derived....
 (animals and fungi) or from the sterol cycloartenol
Cycloartenol

Cycloartenol is a sterol precursor in photosynthesis organisms and plants. The biosynthesis of cycloartenol starts from the triterpenoid squalene. Its structure is also related to triterpenoid lanosterol....
 (plants). Both sterols are derived from the cyclization of the triterpene squalene
Squalene

Squalene is a natural organic compound originally obtained for commercial purposes primarily from shark liver oil, though there are botanic sources as well, including amaranth seed, rice bran, wheat germ, and olives....
.

Origin


Steroids include estrogen
Estrogen

Estrogens are a group of steroid compounds, named for their importance in the estrous cycle, and functioning as the primary female sex hormone....
, cortisol
Cortisol

Cortisol is a corticosteroid hormone or glucocorticoid produced by the adrenal cortex, that is part of the adrenal gland . It is usually referred to as the "stress hormone" as it is involved in response to stress and anxiety, controlled by Corticotropin-releasing hormone....
, progesterone
Progesterone

Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species. Progesterone belongs to a class of hormones called progestogens, and is the major naturally occurring human progestogen....
, and testosterone
Testosterone

Testosterone is a steroid hormone from the androgen group. In mammals, testosterone is primarily secreted in the testis of males and the ovaries of females, although small amounts are also secreted by the adrenal glands....
. Estrogen and progesterone are made primarily in the ovary
Ovary

The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in females are homology to testicle in males, in that they are both gonads and endocrine glands....
 and in the placenta
Placenta

The placenta or afterbirth is a highly vascularized ephemeral organ present in Placentalia vertebrates that connects the developing fetal tissues to the uterine wall....
 during pregnancy, and testosterone
Testosterone

Testosterone is a steroid hormone from the androgen group. In mammals, testosterone is primarily secreted in the testis of males and the ovaries of females, although small amounts are also secreted by the adrenal glands....
 in the testes. Testosterone is also converted into estrogen to regulate the supply of each, in the bodies of both females and males. Certain neurons and glia in the central nervous system
Central nervous system

The central nervous system is the part of the nervous system that functions to coordinate the activity of all parts of the bodies of multicellular organisms....
 (CNS) express the enzymes that are required for the local synthesis of pregnane
Pregnane

Pregnane is, indirectly, a parent of progesterone. It is a parent hydrocarbon for two series of steroids stemming from 5a-pregnane and 5?-pregnane ....
 neurosteroids, either de novo
De novo synthesis

De novo is a Latin phrase, meaning "from the new," anew, or from the beginning. De novo synthesis refers to the synthesis of complex molecules from simple molecules such as sugars or amino acids, as opposed to their being recycled after partial degradation....
 or from peripherally-derived sources. The rate-limiting step of steroid synthesis is the conversion of cholesterol
Cholesterol

Cholesterol is a lipidic, waxy alcohol found in the cell membranes and transported in the blood plasma of all animals. It is an essential component of mammalian cell membranes where it is required to establish proper membrane permeability and membrane fluidity....
 to pregnenolone
Pregnenolone

Pregnenolone is a steroid hormone involved in the steroidogenesis of progesterone, mineralocorticoids, glucocorticoids, androgens, and estrogens....
, which occurs inside the mitochondrion
Mitochondrion

In cell biology, a mitochondrion is a membrane-enclosed organelle found in most eukaryote cell . These organelles range from 0.5–10 micrometers in diameter....
.

Classification


Taxonomical/Functional

Some of the common categories of steroids:
  • Animal steroids
    • Insect
      Insect

      Insects are the biggest class of arthropods and the only ones with wings. They are the most diverse group of animals on the planet. They are most diverse at the equator and their diversity declines toward the poles....
       steroids
      • Ecdysteroids such as ecdysterone
    • Vertebrate
      Vertebrate

      Vertebrates are members of the subphylum Vertebrata, chordates with Vertebras or Vertebral columns. The grouping sometimes includes the hagfish, which have no vertebrae, but are genetically quite closely related to lampreys, which do have vertebrae....
       steroids
      • Steroid hormone
        Steroid hormone

        Steroid hormones are steroids that act as hormones. Steroid hormones can be grouped into five groups by the receptor s to which they bind: glucocorticoids, mineralocorticoids, androgens, estrogens, and progestagens....
        s
        • Sex steroid
          Sex steroid

          Sex steroids, also known as gonadal steroids, are steroid hormones that interact with vertebrate androgen or estrogen receptor s. Their effects are mediated by slow genomic mechanisms through nuclear receptors as well as by fast nongenomic mechanisms through membrane-associated receptors and signaling cascades....
          s are a subset of sex hormones that produce sex differences
          Sexual differentiation

          Sexual differentiation is the process of development of the differences between males and females from an undifferentiated zygote . As male and female individuals develop from zygotes into fetuses, into infants, children, adolescents, and eventually into adults, sex and gender differences at many levels develop: genes, chromosomes, gonads, ho...
           or support reproduction. They include androgen
          Androgen

          Androgen is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of masculine characteristics in vertebrates by binding to androgen receptors....
          s, estrogen
          Estrogen

          Estrogens are a group of steroid compounds, named for their importance in the estrous cycle, and functioning as the primary female sex hormone....
          s, and progestagen
          Progestagen

          Progestagens are a group of hormones including progesterone.The progestagens are one of the five major classes of steroid hormones, in addition to the estrogens, androgens, mineralocorticoids, and glucocorticoids....
          s.
        • Corticosteroid
          Corticosteroid

          Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiology systems such as stress , immune system and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte levels, and behavior....
          s include glucocorticoid
          Glucocorticoid

          Glucocorticoids are a class of steroid hormones which bind to the glucocorticoid receptor , which is present in almost every animal cell.GCs are part of the feedback mechanism in the immune system which turns immune activity down....
          s and mineralocorticoid
          Mineralocorticoid

          Mineralocorticoids are a class of steroid hormones characterised by their similarity to aldosterone and their influence on salt balance and water balance ....
          s. Glucocorticoid
          Glucocorticoid

          Glucocorticoids are a class of steroid hormones which bind to the glucocorticoid receptor , which is present in almost every animal cell.GCs are part of the feedback mechanism in the immune system which turns immune activity down....
          s regulate many aspects of metabolism
          Metabolism

          Metabolism is the set of chemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments....
           and immune function
          Immune system

          An immune system is a collection of biological processes within an organism that protects against disease by identifying and killing pathogens and tumour cells....
          , whereas mineralocorticoid
          Mineralocorticoid

          Mineralocorticoids are a class of steroid hormones characterised by their similarity to aldosterone and their influence on salt balance and water balance ....
          s help maintain blood volume and control renal
          Kidney

          The kidneys are Organ that have numerous biological roles. Their primary role is to maintain the homeostasis balance of bodily fluids by filtering and secreting Metabolomics#Metabolitess and minerals from the blood and excreting them, along with water , as urine....
           excretion of electrolyte
          Electrolyte

          An electrolyte is any substance containing free ions that behaves as an electrical conductor medium. Because they generally consist of ions in solution, electrolytes are also known as ionic solutions, but molten electrolytes and solid electrolytes are also possible....
          s. Most medical 'steroid' drug
          Drug

          A drug, broadly speaking, is any chemical substance that, when absorbed into the body of a living organism, alters normal bodily function....
          s are corticosteroids.
        • Anabolic steroid
          Anabolic steroid

          Anabolic steroids, or anabolic-androgenic steroids , are a class of steroid hormones related to the hormone testosterone. They increase Protein biosynthesis within cells, which results in the buildup of Cell tissue , especially in muscles....
          s are a class of steroids that interact with androgen receptors to increase muscle and bone synthesis. There are natural and synthetic anabolic steroids. In popular language, the word "steroids" usually refers to anabolic steroids.
      • Cholesterol
        Cholesterol

        Cholesterol is a lipidic, waxy alcohol found in the cell membranes and transported in the blood plasma of all animals. It is an essential component of mammalian cell membranes where it is required to establish proper membrane permeability and membrane fluidity....
        , which modulates the fluidity of cell membranes and is the principal constituent of the plaques implicated in atherosclerosis
        Atherosclerosis

        Atherosclerosis is a syndrome affecting artery blood vessels. It is a chronic inflammatory response in the walls of arteries, in large part due to the accumulation of macrophage white blood cells and promoted by low density lipoproteins without adequate removal of fats and cholesterol from the macrophages by functional high density lipoprot...
        .
  • Plant steroids
    • Phytosterol
      Phytosterol

      Phytosterols are a group of sterol, phytochemicals naturally occurring in plants. They are white powders with mild, characteristic odor, insoluble in water and soluble in alcohols....
      s
    • Brassinosteroid
      Brassinosteroid

      Brassinosteroids are a group of steroidal plant hormones. Brassinolide was the first of these steroid compounds discovered in 1973, when it was shown that pollen from Brassica napus could promote stem elongation and cell divisions and that the biologically active molecule was a steroid that the authors called Brassins....
      s
  • Fungus steroids
    • Ergosterol
      Ergosterol

      Ergosterol , a sterol, is a biological precursor to Vitamin D. It is turned into viosterol by ultraviolet light, and is then converted into ergocalciferol, which is a form of Vitamin D....
      s


Structural

It is also possible to classify steroids based upon their chemical composition. One example of how MeSH
Mesh

Mesh consists of semi-permeable barrier made of connected strands of metal, fiber, or other flexible/ductile material. Mesh is similar to spider web or Net in that it has many attached or woven strands....
 performs this classification is available at the Wikipedia MeSH catalog. Examples from this classification include:

Class Examples Number of carbon atoms
Cholstanes cholesterol
Cholesterol

Cholesterol is a lipidic, waxy alcohol found in the cell membranes and transported in the blood plasma of all animals. It is an essential component of mammalian cell membranes where it is required to establish proper membrane permeability and membrane fluidity....
 27
Cholanes cholic acid
Cholic acid

Cholic acid is a bile acid, a white crystalline substance insoluble in water , with a melting point of 200-201 ?C. Salts of cholic acid are called cholates....
 24
Pregnanes progesterone
Progesterone

Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species. Progesterone belongs to a class of hormones called progestogens, and is the major naturally occurring human progestogen....
 21
Androstanes testosterone
Testosterone

Testosterone is a steroid hormone from the androgen group. In mammals, testosterone is primarily secreted in the testis of males and the ovaries of females, although small amounts are also secreted by the adrenal glands....
 19
Estranes estradiol
Estradiol

Estradiol is a sex hormone. Mislabelled the "female" hormone, it is also present in males; it represents the major estrogen in humans. Estradiol has not only a critical impact on reproductive and sexual functioning, but also affects other organs including bone structure....
 18


See also

  • Batrachotoxin
    Batrachotoxin

    Batrachotoxins are extremely potent cardiotoxic and neurotoxic steroids alkaloids found in certain species of frogs , Melyridae beetles, and birds ....
  • List of steroid abbreviations
    List of steroid abbreviations

    The steroid hormones are referred to by various abbreviations in the biological literature. The purpose of this list is to give commonly used abbreviations for steroid hormones, with supporting references to the literature....
  • Steroid biosynthesis


External links

  • . Steroids and retinoids are both terpene
    Terpene

    Terpenes are a large and varied class of hydrocarbons, produced primarily by a wide variety of plants, particularly conifers, though also by some insects such as termites or swallowtail butterflies, which emit terpenes from their osmeterium....
    s that are hydrophobic, pass through cell membrane
    Cell membrane

    The cell membrane is the interface between the cellular machinery inside the cell and the fluid outside.It is a semipermeable lipid bilayer found in all cell ....
    s and bind to intracellular receptors
    Signal transduction

    In biology, 'signal transduction' refers to any process by which a cell converts one kind of signal or stimulus into another. Most processes of signal transduction involve ordered sequences of biochemistry chemical reaction inside the cell, which are carried out by enzymes, activated by Second messenger systems, resulting in a signal tran...
    . However, retinoic acid is not a steroid because it does not have the defining ring structure. See: .
  • "" by Jeremy M. Berg, John L. Tymoczko and Lubert Stryer (2002) W. H. Freeman and Co.
  • -- Video: Insidermedicine.com's Maria Radina on Anabolic Androgenic Steroids, as presented in a study in Archives of General Psychiatry.
  • at Queen Mary University of London.
  • at ISAS (page now defunct, web archive version)