Steroid skeleton of lanosterol. Lanosterol is a tetracyclic triterpenoid, which is the compound from which all Steroids are derived The total number of carbons (30) reflects its triterpenoid origin. The terpenoids, sometimes referred to as isoprenoids, are a large and diverse class of naturally-occurring organic chemicals similar to Terpenes derived

A steroid is a terpenoid lipid characterized by a carbon skeleton with four fused rings, generally arranged in a 6-6-6-5 fashion. The terpenoids, sometimes referred to as isoprenoids, are a large and diverse class of naturally-occurring organic chemicals similar to Terpenes derived Lipids are broadly defined as any fat- Soluble ( lipophilic) naturally-occurring Molecule, such as fats oils waxes cholesterol sterols fat-soluble Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6

Steroids vary by the functional groups attached to these rings and the oxidation state of the rings. In Organic chemistry, functional groups are specific groups of Atoms within Molecules that are responsible for the characteristic Chemical reactions Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Hundreds of distinct steroids are found in plants, animals, and fungi. Plants are living Organisms belonging to the kingdom Plantae. A fungus (ˈfʌŋgəs is a eukaryotic Organism that is a member of the kingdom Fungi (ˈfʌndʒaɪ All steroids are made in cells either from the sterol lanosterol (animals and fungi) or the sterol cycloartenol (plants). Sterols, or steroid alcohols are a subgroup of Steroids with a Hydroxyl group at the 3-position of the A-ring Lanosterol is a tetracyclic triterpenoid, which is the compound from which all Steroids are derived Cycloartenol is a Sterol precursor in photosynthetic organisms and plants Both sterols are derived from the cyclization of the triterpene squalene. 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 Squalene is a natural Organic compound originally obtained for commercial purposes primarily from Shark liver oil, though there are botanic sources as well including ^[1]

Origin

Simplified version of the steroid synthesis pathway with the intermediates isopentenyl pyrophosphate (IPP), dimethylallyl pyrophosphate (DMAPP), geranyl pyrophosphate (GPP) and squalene shown. Isopentenyl pyrophosphate (IPP is an intermediate in the classical HMG-CoA reductase pathway used by organisms in the biosynthesis of Terpenes and Terpenoids Dimethylallyl pyrophosphate (or -diphosphate (DMAPP is an intermediate product of both Mevalonic acid (MVA pathway and DOXP/ MEP pathway Geranyl pyrophosphate is an intermediate in the HMG-CoA reductase pathway used by organisms in the biosynthesis of Farnesyl pyrophosphate, Geranylgeranyl pyrophosphate Squalene is a natural Organic compound originally obtained for commercial purposes primarily from Shark liver oil, though there are botanic sources as well including Some intermediates are omitted.

Steroids include estrogen (US spelling) or oestrogen (UK/AUS spelling), progesterone and testosterone. Estrogens (US otherwise oestrogens or œstrogens) are a group of Steroid compounds named for their importance in the Estrous cycle, Progesterone is a C-21 Steroid Hormone involved in the Female Menstrual cycle, Pregnancy (supports Gestation Testosterone is a Steroid hormone from the Androgen group In mammals testosterone is primarily secreted in the testes of males and the Ovaries Estrogen and progesterone are made primarily in the ovary and in the placenta during pregnancy and testosterone in the testes. "Ovaria" redirects here This is also a proposed section and a Synonym of Solanum. The placenta is an Ephemeral organ present in placental Vertebrates, such as Eutherial Mammals and Sharks during Gestation Testosterone is a Steroid hormone from the Androgen group In mammals testosterone is primarily secreted in the testes of males and the Ovaries The testicle (from Latin testiculus, diminutive of testis, meaning "witness" virility plural testes) is the male 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 (CNS) express the enzymes that are required for the local synthesis of pregnane neurosteroids, either de novo or from peripherally derived sources. Neurons (ˈnjuːɹɒn also known as neurones and nerve cells) are responsive cells in the Nervous system that process and transmit information Glial cells, commonly called neuroglia or simply glia (Greek for "glue" are non- Neuronal cells that provide support and nutrition In Vertebrates the central nervous system ( CNS) is the part of the Nervous system which is enclosed in the Meninges. Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins Pregnane is indirectly a parent of Progesterone. It is a parent Hydrocarbon for two series of steroids stemming from 5α-pregnane (originally allopregnane Neuroactive Steroids (or neurosteroids') rapidly alter Neuronal excitability through interaction with Neurotransmitter[[ligand gated ion channel|-gated De novo is a Latin phrase, meaning "from the new" anew or from the beginning The rate limiting step of steroid synthesis is the conversion of cholesterol to pregnenolone which occurs inside the mitochondrion. Cholesterol is a Lipid found in the Cell membranes and transported in the Blood plasma of all Animals It is an essential component of mammalian Pregnenolone is a Steroid hormone involved in the Steroidogenesis of Progesterone, Mineralocorticoids, Glucocorticoids, Androgens In Cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed Organelle found in most eukaryotic cells. ^[2]

Classification

Taxonomical/Functional

Some of the common categories of steroids:

• Animal steroids
  • Insect steroids
    • Ecdysteroids such as ecdysterone
  • Vertebrate steroids
    • Steroid hormones
      • Sex steroids are a subset of sex hormones that produce sex differences or support reproduction. Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described 20-Hydroxyecdysone ( ecdysterone or 20E) is a naturally occurring Ecdysteroid Hormone which controls the Ecdysis (moulting and Vertebrates are members of the Subphylum Vertebrata, Chordates with backbones or spinal columns The grouping sometimes includes Steroid hormones are Steroids which act as Hormones Mammalian steroid hormones can be grouped into five groups by the receptors to which they bind Sex steroids, also known as gonadal steroids, are Steroid hormones that interact with Vertebrate Androgen or Estrogen receptors Sex steroids, also known as gonadal steroids, are Steroid hormones that interact with Vertebrate Androgen or Estrogen receptors See Sex differences in humans for permanent sex differences Sexual differentiation is the process of development of the differences between Reproduction is the Biological process by which new individual Organisms are produced They include androgens, estrogens, and progestagens. 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 Estrogens (US otherwise oestrogens or œstrogens) are a group of Steroid compounds named for their importance in the Estrous cycle, Progestagens (also spelled progestogens or gestagens) are Hormones that produce effects similar to those of Progesterone, the only natural progestagen
      • Corticosteroids include glucocorticoids and mineralocorticoids. Corticosteroids are a class of Steroid hormones that are produced in the Adrenal cortex. Glucocorticoids (GC are a class of Steroid hormones characterised by an ability to bind with the glucocorticoid receptor ( GR) and trigger similar effects Mineralocorticoids are a class of Steroid hormones characterised by their similarity to Aldosterone and their influence on salt and water balance Glucocorticoids regulate many aspects of metabolism and immune function, whereas mineralocorticoids help maintain blood volume and control renal excretion of electrolytes. Glucocorticoids (GC are a class of Steroid hormones characterised by an ability to bind with the glucocorticoid receptor ( GR) and trigger similar effects Metabolism is the set of Chemical reactions that occur in living Organisms in order to maintain Life. An immune system is a collection of mechanisms within an Organism that protects against Disease by identifying and killing Pathogens and Tumor Mineralocorticoids are a class of Steroid hormones characterised by their similarity to Aldosterone and their influence on salt and water balance The kidneys are complicated organs that have numerous biological roles An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium
      • Anabolic steroids are a class of steroids that interact with androgen receptors to increase muscle and bone synthesis. Anabolic steroids, or anabolic-androgenic steroids ( AAS) are a class of Steroid hormones related to the hormone Testosterone. There are natural and synthetic anabolic steroids. In popular language the word "steroids" usually refers to anabolic steroids.
    • Cholesterol which modulates the fluidity of cell membranes and is the principle constituent of the plaques implicated in atherosclerosis. Cholesterol is a Lipid found in the Cell membranes and transported in the Blood plasma of all Animals It is an essential component of mammalian The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer Atherosclerosis is a Disease affecting arterial Blood vessels It is a chronic inflammatory response in the walls of arteries in large part due to the accumulation
• Plant steroids
  • Phytosterols
  • Brassinosteroids
• Fungus steroids
  • Ergosterols

Structural

It is also possible to classify steroids based upon their chemical composition. Phytosterols (also called plant sterols) are a group of steroid alcohols, Phytochemicals naturally occurring in Plants. Brassinosteroids (BR are a group of steroidal Plant hormones. Ergosterol (ergosta-5722-trien-3β-ol a Sterol, is a biological precursor (a Provitamin) to Vitamin D2. One example of how MeSH performs this classification is available at the Wikipedia MeSH catalog. Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Examples from this classification include:

See also

• Batrachotoxin
• List of steroid abbreviations
• Steroid biosynthesis

References

Further reading

• G. P. Moss (1989). "Nomenclature of Steroids (Recommendations 1989)". Pure & Appl. Chem. 61 (10): 1783-1822. Pure and Applied Chemistry (abb Pure Appl Chem) is the official journal for the International Union of Pure and Applied Chemistry.  

External links

• Michael W. King's Medical Biochemistry. Steroids and retinoids are both terpenes which are hydrophobic, pass through cell membranes and bind to intracellular receptors. 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 In Chemistry, hydrophobicity (from the combining form of water in Attic Greek hydro- and for fear phobos) refers to the physical property of The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer In Biology, signal transduction refers to any process by which a cell converts one kind of signal or stimulus into another However, retinoic acid is not a steroid because it does not have the defining ring structure. See: Steroids and Related Hydrophobic Molecules.
• "Biochemistry" by Jeremy M. Berg, John L. Tymoczko and Lubert Stryer (2002) W. H. Freeman and Co. steroid topics in this
• Steroids, Rage and Criminal Activity -- Video: Insidermedicine. com's Maria Radina on Anabolic Androgenic Steroids, as presented in a study in Archives of General Psychiatry.
• Nomenclature of Steroids Home Page at Queen Mary University of London.
• Steroid abbreviations at ISAS (page now defunct, web archive version)