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Inositol, or more precisely myo-inositol, is a carbocyclic sugar that is abundant in brain and other mammalian tissues, mediates cell signal transduction in response to a variety of hormones, neurotransmitters and growth factors and participates in osmoregulation. [2] It is a sugar alcohol with half the sweetness of sucrose (table sugar). It is made naturally in humans from glucose. Each kidney makes 2g a day; so 4g a day total is made. Other tissues synthesize it too, and the highest concentration is in the brain where it plays an important role making other neurotransmitters, and some steroid hormones bind to their receptors.[3]

IUPAC name
Other names
cis-1,2,3,5-trans-4,6-cyclohexanehexol, cyclohexanehexol, mouse antialopecia factor,
nucite, phaseomannite, phaseomannitol,
rat antispectacled eye factor,
scyllite (for the structural isomer scyllo-inositol)
3D model (JSmol)
Molar mass 180.16 g/mol
Density 1.752 g/cm3
Melting point 225 to 227 °C (437 to 441 °F; 498 to 500 K)
A11HA07 (WHO)
NFPA 704
Flammability code 0: Will not burn. E.g., waterHealth code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
Flash point 143 °C (289 °F; 416 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references



myo-Inositol plays an important role as the structural basis for a number of secondary messengers in eukaryotic cells, the various inositol phosphates. In addition, inositol serves as an important component of the structural lipids phosphatidylinositol (PI) and its various phosphates, the phosphatidylinositol phosphate (PIP) lipids.

Inositol or its phosphates and associated lipids are found in many foods, in particular fruit, especially cantaloupe and oranges.[4] In plants, the hexaphosphate of inositol, phytic acid or its salts, the phytates, serve as phosphate stores in seed, for example in nuts and beans.[5] Phytic acid also occurs in cereals with high bran content. Phytate is, however, not directly bioavailable to humans in the diet, since it is not digestible. Some food preparation techniques partly break down phytates to change this. However, inositol in the form of glycerophospholipids, as found in certain plant-derived substances such as lecithins is well-absorbed and relatively bioavailable.

myo-Inositol (free of phosphate) was once considered a member of the vitamin B complex, called Vitamin B8 in this context. However, because it is produced by the human body from glucose, it is not an essential nutrient.[6]

Isomers and structureEdit

The isomer myo-inositol is a meso compound, and hence optically inactive, because it has a plane of symmetry. For this reason, meso-inositol is an obsolete name for this compound. Besides myo-inositol, the other naturally occurring stereoisomers are scyllo-, muco-, D-chiro-, and neo-inositol, although they occur in minimal quantities in nature. The other possible isomers are L-chiro-, allo-, epi-, and cis-inositol. As their names denote, L- and D-chiro inositol are the only pair of inositol enantiomers, but they are enantiomers of each other, not of myo-inositol.[7]

myo- scyllo- muco- chiro-
neo- allo- epi- cis-

In its most stable conformation, the myo-inositol isomer assumes the chair conformation, which moves the maximum number of hydroxyls to the equatorial position, where they are farthest apart from each other. In this conformation, the natural myo isomer has a structure in which five of the six hydroxyls (the first, third, fourth, fifth, and sixth) are equatorial, whereas the second hydroxyl group is axial.[8]


myo-Inositol is synthesized from glucose-6-phosphate (G-6-P) in two steps. First, G-6-P is isomerised by an inositol-3-phosphate synthase enzyme (for example, ISYNA1) to myo-inositol 1-phosphate, which is then dephosphorylated by an inositol monophosphatase enzyme (for example, IMPA1) to give free myo-inositol. In humans, most inositol is synthesized in the kidneys, typically in amounts of a few grams per day.[9]


Inositol, phosphatidylinositol and some of their mono- and polyphosphates function as secondary messengers in a number of intracellular signal transduction pathways. They are involved in a number of biological processes, including:

In one important family of pathways, phosphatidylinositol 4,5-bisphosphate (PIP2) is stored in cellular membranes until it is released by any of a number of signalling proteins and transformed into various secondary messengers, for example diacylglycerol and inositol triphosphate.[16]

Phytic acid in plantsEdit

Inositolhexaphosphate, or phytic acid.

Inositolhexaphosphate, also called phytic acid or IP6, is the principal storage form of phosphorus in many plant tissues, especially bran and seed.[17] Phosphorus and inositol in phytate form are not generally bioavailable to non-ruminant animals because these animals lack the digestive enzyme phytase required to remove the phosphate groups. Ruminants are readily able to digest phytate because of the phytase produced by rumen microorganisms.[18] Moreover, phytic acid also chelates important minerals such as calcium, magnesium, iron, and zinc, making them unabsorbable, and contributing to mineral deficiencies in people whose diets rely highly on bran and seeds for their mineral intake, such as occurs in developing countries.[19][20]

Inositol penta- (IP5), tetra- (IP4), and triphosphate (IP3) are also called "phytates".

Use in explosives manufactureEdit

At the 1936 meeting of the American Chemical Society, professor Edward Bartow of the University of Iowa presented a commercially viable means of extracting large amounts of inositol from the phytic acid naturally present in waste corn. As a possible use for the chemical, he suggested 'inositol nitrate' as a more stable alternative to nitroglycerin.[21] Today, inositol nitrate is used to gelatinize nitrocellulose, thus can be found in many modern explosives and solid rocket propellants.[22]

Counter to road saltEdit

When plants are exposed to increasing concentrations of road salt, the plant cells become dysfunctional and undergo apoptosis, leading to inhibited growth. Inositol pretreatment could reverse these effects.[23][24]

Research and clinical applicationsEdit

Large doses of inositol have been studied for treatment of depression, but insufficient evidence exists to determine whether this is an effective treatment.[25]

Inositol is effective in the management of preterm babies who have or are at a risk of infant respiratory distress syndrome (RDS).[26]

Inositol is considered a safe and effective treatment for polycystic ovary syndrome (PCOS). It works by increasing insulin sensitivity, which helps to improve ovarian function and reduce hyperandrogenism.[27] It is also shown to reduce the risk of metabolic disease in people with PCOS.[28]

Use as a cutting agentEdit

Inositol has been used as an adulterant or cutting agent for many illegal drugs, such as cocaine, methamphetamine, and sometimes heroin,[29] probably because of its solubility, powdery texture, or reduced sweetness (50%) compared to more common sugars.

Inositol is also used as a stand-in film prop for cocaine in filmmaking.[30]

Nutritional sourcesEdit

myo-Inositol is naturally present in a variety of foods, although tables of food composition do not always distinguish between lecithin, the bioavailable form, and the unavailable phytate form in grains.[4] Foods containing the highest concentrations of myo-inositol (including its compounds) include fruits, beans, grains, and nuts.[4] Beans and grains, however, contain large amounts of phytate.


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External linksEdit