Inositol

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, particularly in cereals with high bran content, nuts, beans, and fruit, especially cantaloupe melons and oranges. Inositol is not considered a vitamin itself because it is not a vital amine (contains no nitrogen) and is 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.

Structure
The chemical formula of myo-inositol is 6126. 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, while the 2nd hydroxyl group is axial.

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:
 * Insulin signal transduction
 * Cytoskeleton assembly
 * Nerve guidance (Epsin)
 * Intracellular calcium (Ca2+) concentration control
 * Cell membrane potential maintenance
 * Serotonin activity modulation
 * Breakdown of fats and reducing blood cholesterol
 * Gene expression

Clinical implications
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. The impetuses for these studies were the observed defects in DCI metabolism in PCOS and the implication of DCI in insulin signal transduction.

Myo-inositol has been found in double-blind studies to be an effective treatment for obsessive-compulsive disorder (OCD). It is equal in effectiveness to SSRIs and is virtually free from side effects.

Animal studies suggest inositol reduces the severity of the osmotic demyelination syndrome if given prior to rapid correction of chronic hyponatraemia. 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, particularly when used in combination with phytic acid.

Other uses
Myo-Inositol powder can be used in small proportions as a cutting agent for cocaine or methamphetamine ("crystal meth"). It has an almost identical appearance when in powder form and portrays similar qualities when heated. This, in addition to the fact that it adds almost no discernable taste or feel to either drug regardless the method of use, makes it an ideal cutting agent. Cutting either drug at any point in the distribution increases volume of the street product and increases dealer profits. However, at higher cut levels the inositol becomes somewhat noticeable in that the quality of the product is obviously diminished.