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Infobox disclaimer and references
Inositol, (of which the most prominent naturally-occurring form is myo-inositol, cis-1,2,3,5-trans-4,6-cyclohexanehexol), is a carbocyclic polyol that plays an important role as the structural basis for a number of secondary messengers in eukaryotic cells, including inositol phosphates, phosphatidylinositol (PI) and phosphatidylinositol phosphate (PIP) lipids. It is found in many foods, in particular, in cereals with high bran content, nuts, beans, and fruit, especially cantaloupe melons and oranges. Inositol is not considered a vitamin itself because it can be synthesised by the body.
Other naturally-occurring isomers (though in minimal quantities) are scyllo-, chiro-, muco-, and neo-inositol. Other possible isomers are allo-, epi-, and cis-inositol.
Myo-Inositol is classified as a member of the vitamin B complex (often referred to as vitamin B8), and is synthesized by the human body.
The chemical formula of myo-inositol is C6H12O6. In its most stable geometry, the inositol ring is in the chair conformation. There are nine stereoisomers, all of which may be referred to as inositol; however, the natural isomer has a structure in which the 1st, 3rd, 4th, 5th, and 6th hydroxyls are equatorial, whereas the 2nd hydroxyl group is axial.[2]
Synthesis
Myo-Inositol is synthesized from glucose-6-phosphate (G-6-P) in two steps. First, G-6-P is isomerised by INYNA1 to myo-inositol 1-phosphate, which is then dephosphorylated by IMPA1 to give myo-inositol.
Function
Inositol as the basis for a number of signalling and secondary messenger molecules, is involved in a number of biological processes, including:
Some preliminary results of studies on inositol supplements show promising results for people suffering from problems such as bulimia, panic disorder, and bipolar depression.
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.[6][7] The impetuses for these studies were the observed defects in DCI metabolism in PCOS and the implication of DCI in insulin signal transduction.[8][9]
Animal studies suggest inositol reduces the severity of the osmotic demyelination syndrome if given prior to rapid correction of chronic hyponatraemia.[13] Further study is required prior to 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.[14][15]
^ S. M. N. Furse (2006). The Chemical and Bio-physical properties of Phosphatidylinositol phosphates, Thesis for M.Res.. Imperial College London.
^ Larner J (2002). "D-chiro-inositol--its functional role in insulin action and its deficit in insulin resistance". Int J Exp Diabetes Res3 (1): 47–60. PMID 11900279.
^ (2003) "Modulation of ATP-dependent chromatin-remodeling complexes by inositol polyphosphates". Science299 (5603): 112-4. PMID 12434013.
^ (2003) "Regulation of chromatin remodelling by inositol polyphosphates". Science299 (5603): 114-6. PMID 12434012.
^ Nestler J E, Jakubowicz D J, Reamer P, Gunn R D, Allan G (1999). "Ovulatory and metabolic effects of D-chiro-inositol in the polycystic ovary syndrome". N Engl J Med340 (17): 1314–1320. PMID 10219066.
^ Iuorno M J, Jakubowicz D J, Baillargeon J P, Dillon P, Gunn R D, Allan G, Nestler J E (2002). "Effects of d-chiro-inositol in lean women with the polycystic ovary syndrome". Endocr Pract8 (6): 417–423. PMID 15251831.
^ Larner J (2002). "D-chiro-inositol--its functional role in insulin action and its deficit in insulin resistance". Int J Exp Diabetes Res3 (1): 47–60. PMID 11900279.
^ Nestler J E, Jakubowicz D J, Iuorno M J (2000). "Role of inositolphosphoglycan mediators of insulin action in the polycystic ovary syndrome". J Pediatr Endocrinol Metab13 Suppl 5: 1295–1298. PMID 11117673.
^ 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 Psychopharmacology21 (3): 335–339. PMID 11386498.
^ Fux M, Levine J, Aviv A, Belmaker RH (1996). "Inositol treatment of obsessive-compulsive disorder". American Journal of Psychiatry153 (9): 1219–21. PMID 8780431.
^ Di Paolo G, De Camilli P (2006). "Phosphoinositides in cell regulation and membrane dynamics". Nature443 (7112): 651-7. PMID 17035995.
^ 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 Neurol65 (1): 37-44. PMID 16410747.
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