Inositol

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myo-Inositol[1]
myo-Inositol
myo-Inositol
Identifiers
CAS number 87-89-8 YesY
PubChem 892
ChemSpider 10239179 YesY
UNII 4L6452S749 YesY
KEGG D08079 YesY
ChEBI CHEBI:17268 YesY
ChEMBL CHEMBL1222251 YesY
ATC code A11HA07
Jmol-3D images Image 1
Properties
Molecular formula C6H12O6
Molar mass 180.16 g mol−1
Density 1.752 g/cm³
Melting point 225–227 °C
Hazards
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 143 °C (289 °F; 416 K)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

Inositol or cyclohexane-1,2,3,4,5,6-hexol is a chemical compound with formula C6H12O6 or (-CHOH-)6, a sixfold alcohol (polyol) of cyclohexane. It exists in nine possible stereoisomers, of which the most prominent form, widely occurring in nature, is cis-1,2,3,5-trans-4,6-cyclohexanehexol, or myo-inositol (former names meso-inositol or i-inositol).[2][3] Inositol is a carbohydrate, though not a classical sugar. It has a taste which has been assayed at half the sweetness of table sugar (sucrose).[4][5]

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.[6] In plants, the hexaphosphate of inositol, phytic acid or its salts, the phytates, are found. These serve as phosphate stores in the seed. Phytic acid occurs also in cereals with high bran content and also nuts and beans. Yet, inositol, when present as phytate is not directly bioavailable to humans in the diet, since it is not digestible. Some food preparation techniques partly break down phytates to change this. Inositol as it occurs in certain plant-derived substances such as lecithins, however, is well-absorbed and relatively bioavailable.

myo-Inositol (free of phosphate) was once considered a member of the vitamin B complex; however, because it is produced by the human body from glucose, it is not an essential nutrient.[7] Some substances such as niacin can also be synthesized in the body, but are not made in amounts considered adequate for good health, and thus are still classified as essential nutrients. However, there is no convincing evidence that this is the case for myo-inositol.

Isomers and structure[edit]

The isomer myo-inositol is a meso compound possessing an optically inactive plane of symmetry through the molecule, and meso-inositol is an obsolete name that refers to myo-inositol. Besides myo-inositol, the other naturally occurring stereoisomers (though in minimal quantities) are scyllo-, muco-, D-chiro-, and neo-inositol. The other possible isomers are L-chiro-, allo-, epi-, and cis-inositol. As their name denotes, the two chiro inositols are the only pair of inositol enantiomers, but they are enantiomers of each other, not of myo-inositol.

Myo-inositol.svg Scyllo-inositol.svg Muco-inositol.svg Chiro-inositol.svg
myo- scyllo- muco- chiro-
Neo-inositol.svg Allo-inositol.svg Epi-inositol.svg
Cis-inositol.svg
neo- allo- epi- cis-

In its most stable conformational geometry, the myo-inositol isomer assumes the chair conformation, which puts 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 1st, 3rd, 4th, 5th, and 6th) are equatorial, whereas the 2nd hydroxyl group is axial.[8]

Synthesis[edit]

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 (called ISYNA1) to myo-inositol 1-phosphate, which is then dephosphorylated by an inositol monophosphatase enzyme (called IMPase 1) to give free myo-inositol. In humans most inositol is synthesized in the kidneys, in typical amounts of a few grams per day.[9]

Function[edit]

Inositol and some of its mono and polyphosphates function as the basis for a number of signaling and secondary messenger molecules. They are involved in a number of biological processes, including:


Phytic acid in plants[edit]

Phytic acid, which is inositol hexakisphosphate (IP6), also known as phytate when in salt form, is the principal storage form of phosphorus in many plant tissues, especially bran and seeds.[16] Neither the inositol nor the phosphate in phytic acid in plants is available to humans, or to animals that are not ruminants, since it cannot be broken down, except by bacteria. 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.[17][18]

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

Explosive potential[edit]

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.[19] Today, inositol nitrate is used to gelatinize nitrocellulose, and thus can be found in many modern explosives and solid rocket propellants.[20]

Counter to road salt[edit]

When plants are exposed to increasing concentrations of road salt, the plant cells become dysfunctional, and commit apoptosis, leading to an inhibition of growth in plants. Inositol pretreatment could reverse the effects of salt on plants.[citation needed]

Clinical applications[edit]

Psychiatric conditions[edit]

Some preliminary results of studies on high-dose inositol supplements show promising results for people suffering from problems such as bulimia, panic disorder, obsessive-compulsive disorder (OCD), agoraphobia, and unipolar and bipolar depression.[21][22][23]

Eur Neuropsychopharmacol. 1997 May;7(2):147-55.

In a single double-blind study on 13 patients, myo-inositol (18 grams daily) has been found to reduce the symptoms of OCD significantly, with effectiveness equal to SSRIs and virtually without side-effects.[24] In a double-blind, controlled trial, myo-inositol (18 grams daily) was superior to fluvoxamine for decreasing the number of panic attacks and other side-effects.[21]

Similarly large doses of inositol have been studied for treatment of depression. A 2004 meta-analysis by the Cochrane Collaboration found four randomized controlled trials, with mixed results. The authors concluded that there is insufficient evidence to determine whether inositol treatment can reduce depression symptoms, but that there is also no evidence of harm or negative side effects [25]

Other studies suggest that lithium treatment may further inhibit the enzyme inositol monophosphatase, leading to higher intracellular levels of inositol triphosphate,[26] an effect that was enhanced further by administration of an inositol triphosphate reuptake inhibitor.

Other conditions[edit]

D-chiro-Inositol (DCI) has been found in two double-blind studies to be an effective treatment for many of the clinical hallmarks of polycystic ovary syndrome (PCOS), including insulin resistance, hyperandrogenism, and oligo-amenorrhea;[27][28] the impetuses for these studies were the observed defects in DCI metabolism in PCOS and the implication of DCI in insulin signal transduction.[10][29] Another small, placebo-controlled study has demonstrated that myo-inositol supplementation improves features of dysmetabolic syndrome in post-menopausal women, including triglycerides, HDL cholesterol, and diastolic blood pressure.[30]

Animal studies suggest inositol reduces the severity of the osmotic demyelination syndrome if given before rapid correction of chronic hyponatraemia.[31] Further study is required before its application in humans for this indication.

Studies from in vitro experiments, animal studies, and limited clinical experiences, claim that inositol may be used effectively against some types of cancer, in particular, when used in combination with phytic acid.[32]

Common use as a "cutting" agent[edit]

Inositol has been used as an adulterant (or cutting agent) in many illegal drugs, such as cocaine, methamphetamine, and sometimes heroin.[33] It is presumed that this use is connected with one or more of the substance's properties of solubility, powdery texture, or reduced sweetness (50%) as compared with more common sugars.

Inositol is also used as a stand-in for cocaine on television.[34]

Nutritional sources[edit]

myo-Inositol is naturally present in a variety of foods, although tables of this do not always distinguish between the bioavailable lecithin form, and the non-available phytate form in grains.[35] According to research, foods containing the highest concentrations of myo-inositol (including its compounds) include fruits, beans, grains and nuts.[35] Beans and grains, however, as seeds, contain large amounts of inositol as phytate.

See also[edit]

References[edit]

  1. ^ Merck Index, 11th Edition, 4883.
  2. ^ Synonyms in PubChem
  3. ^ Synonyms in Commonchemistry.org
  4. ^ Chinese mfgr.
  5. ^ Another Chinese mfgr.
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  7. ^ Reynolds, James E. F. (January 1, 1993). Martindale: The Extra Pharmacopoeia 30. Pennsylvania: Rittenhouse Book Distributors. p. 1379. ISBN 0-85369-300-5. "An isomer of glucose that has traditionally been considered to be a B vitamin although it has an uncertain status as a vitamin and a deficiency syndrome has not been identified in man" 
  8. ^ S. M. N. Furse (2006). The Chemical and Bio-physical properties of Phosphatidylinositol phosphates, Thesis for M.Res. Imperial College London. 
  9. ^ Subcell Biochem. 2006;39:293-314. Mammalian inositol 3-phosphate synthase: its role in the biosynthesis of brain inositol and its clinical use as a psychoactive agent. Parthasarathy LK, Seelan RS, Tobias C, Casanova MF, Parthasarathy RN.
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  11. ^ Gerasimenko, Julia V; et al; “Bile Acids Induce Ca2+ Release from Both the Endoplasmic Reticulum and Acidic Intracellular Calcium Stores through Activation of Inositol Trisphosphate Receptors and Ryanodine Receptors”; Journal of Biological Chemistry; December 29, 2006; Volume 281: Pp 40154-40163.
  12. ^ Kukuljan M, Vergara L, Stojilkovic SS (February 1997). "Modulation of the kinetics of inositol 1,4,5-trisphosphate-induced [Ca2+]i oscillations by calcium entry in pituitary gonadotrophs". Biophysical Journal 72 (2 Pt 1): 698–707. Bibcode:1997BpJ....72..698K. doi:10.1016/S0006-3495(97)78706-X. PMC 1185595. PMID 9017197. 
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  16. ^ Phytic acid
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  19. ^ Laurence, William L. "Corn by-product yields explosive", The New York Times. April 17, 1936. Page 7.
  20. ^ Ledgard, Jared. The Preparatory Manual of Explosives, 2007. p. 366.
  21. ^ a b Palatnik A, Frolov K, Fux M, Benjamin J (2001). "Double-blind, controlled, crossover trial of inositol versus fluvoxamine for the treatment of panic disorder". Journal of Clinical Psychopharmacology 21 (3): 335–339. doi:10.1097/00004714-200106000-00014. PMID 11386498. 
  22. ^ Levine J, Barak Y, Gonzalves M, Szor H, Elizur A, Kofman O, Belmaker RH. (1995). "Double-blind, controlled trial of inositol treatment of depression". American Journal of Psychiatry 152 (5): 792–794. PMID 7726322. 
  23. ^ Levine J (1997). "Controlled trials of inositol in psychiatry". Eur Neuropsychopharmacol. 7 (May;7): 147–55. doi:10.1016/S0924-977X(97)00409-4. PMID 9169302. 
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  30. ^ Giordano D, Corrado F, Santamaria A, Quattrone S, Pintaudi B, DiBenedetto A, D’Anna R (2011). "Effects of myo-inositol supplementation in postmenopausal women with metabolic syndrome: a perspective, randomized, placebo-controlled study". Menopause: the Journal of the North American Menopause Society 18 (1): 102–104. doi:10.1097/gme.0b013e3181e8e1b1. 
  31. ^ Silver SM, Schroeder BM, Sterns RH, Rojiani AM (2006). "Myoinositol administration improves survival and reduces myelinolysis after rapid correction of chronic hyponatremia in rats". J Neuropathol Exp Neurol 65 (1): 37–44. doi:10.1097/01.jnen.0000195938.02292.39. PMID 16410747. 
  32. ^ Vucenik, I; Shamsuddin, AM (2003). "Cancer inhibition by inositol hexaphosphate (IP6) and inositol: from laboratory to clinic". The Journal of nutrition 133 (11 Suppl 1): 3778S–3784S. PMID 14608114. 
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  34. ^ Golianopoulos, Thomas. "Drug Doubles: What Actors Actually Toke, Smoke and Snort on Camera". Wired Magazine. Retrieved 14 May 2012. 
  35. ^ a b Clements, Rex; Betty Darnell (1980). "Myo-inositol content of common foods: development of a high-myo-inositol diet". American Journal of Clinical Nutrition 33 (9): 1954–1967. PMID 7416064. Retrieved 2009-05-18. 

External links[edit]