organic chemistry Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...

, a cyclitol is a

cycloalkane In organic chemistry, the cycloalkanes (also called naphthenes, but distinct from naphthalene) are the monocyclic saturated hydrocarbons. In other words, a cycloalkane consists only of hydrogen and carbon atoms arranged in a structure containing ...

containing at least three

hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...

, each attached to a different ring carbon atom. The general formula for an unsubstituted cyclitol is or where 3 ≤ ''x'' ≤ ''n''. The name is also used for compounds that can be viewed as result of substituting various

functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest ...

s for the

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

atoms in such a molecule, as well as similar molecules with one or more

double bond In chemistry, a double bond is a covalent bond between two atoms involving four bonding electrons as opposed to two in a single bond. Double bonds occur most commonly between two carbon atoms, for example in alkenes. Many double bonds exist betw ...

s in the ring. Cyclitols and their derivatives are some of the

compatible solutes Osmoprotectants or compatible solutes are small organic molecules with neutral charge and low toxicity at high concentrations that act as osmolytes and help organisms survive extreme osmotic stress. Osmoprotectants can be placed in three chemical ...

which are formed in a plant as a response to salt or water stress. Some cyclitols (e.g. quinic or

shikimic acid Shikimic acid, more commonly known as its anionic form shikimate, is a cyclohexene, a cyclitol and a cyclohexanecarboxylic acid. It is an important biochemical metabolite in plants and microorganisms. Its name comes from the Japanese flower ''shik ...

) are parts of

hydrolysable tannin A hydrolyzable tannin or pyrogallol-type tannin is a type of tannin that, on heating with hydrochloric or sulfuric acids, yields gallic or ellagic acids. At the center of a hydrolyzable tannin molecule, there is a carbohydrate (usually D-glucose ...

Isomerism and nomenclature

Unsubstituted cyclitols with the same ring size and number of hydroxyls may exist in several

structural isomer In chemistry, a structural isomer (or constitutional isomer in the IUPAC nomenclature) of a chemical compound, compound is another compound whose molecule has the same number of atoms of each element, but with logically distinct chemical bond, b ...

s, depending on the position of the hydroxyls along the ring. For example, cyclohexanetriol exists in three distinct isomers (1,2,3-, 1,2,4-, and 1,3,5-). Furthermore, the hydrogen and the hydroxyl on each carbon atom may lie in two possible arrangements relative to the local ring plane; so that each structural isomer may exist in several

stereoisomer In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in ...

s, depending on which side of the ring plane the hydroxyls are. For example, there are nine stereoisomers of 1,2,3,4,5,6-cyclohexanehexol (

inositol Inositol, or more precisely ''myo''-inositol, is a carbocyclic sugar that is abundant in the brain and other mammalian tissues; it mediates cell signal transduction in response to a variety of hormones, neurotransmitters, and growth factors and ...

), and two of them are

enantiomer In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical ant ...

s. The

IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...

has provided a nomenclature for cyclitol stereoisomers.CON and CBN IUPAC Commissions on Nomenclature (1968): "The Nomenclature of Cyclitols - Tentative Rules". ''European Journal of Biochemistry'', volume 5, pages 1-12.

Naturally occurring cyclitols

Unsubstituted

* Conduritol, or cyclohex-5-ene-1,2,3,4-tetrol; two out of ten possible isomers. *

Inositol Inositol, or more precisely ''myo''-inositol, is a carbocyclic sugar that is abundant in the brain and other mammalian tissues; it mediates cell signal transduction in response to a variety of hormones, neurotransmitters, and growth factors and ...

, or cyclohexane-1,2,3,4,5,6-hexol; four out of nine possible isomers. *

Cyclohexanetetrol A cyclohexanetetrol is a chemical compound consisting of a cyclohexane molecule with four hydroxyl groups (–OH) replacing four of the twelve hydrogen atoms. It is therefore a cyclitol (cyclic polyol). Its generic formula is or . Some cyclohexa ...

J. S. Craigie (1969): "Some Salinity-Induced Changes in Growth, Pigments, and Cyclohexanetetrol Content of ''Monochrysis lutheri''". ''Journal of the Fisheries Research Board of Canada'', volume 26, issue 11, pages 2959-2967.

Substituted

Bornesitol Bornesitol is a cyclitol. It can be found in the gentianaceae and menyanthaceae plant families. Chemically, it is a methyl ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected ...

; (1R,2R,3S,4S,5R,6S)-6-methoxycyclohexane-1,2,3,4,5-pentol; D-(−)-O-methyl-''myo''-inositol *

Pinitol Pinitol is a cyclitol, a cyclic polyol. It is a known anti-diabetic agent isolated from '' Sutherlandia frutescens'' leaves. Gall plant tannins can be differentiated by their content of pinitol. It was first identified in the sugar pine (''Pinus ...

; (1S,2S,4S,5R)-6-methoxycyclohexane-1,2,3,4,5-pentol; 3-O-methyl-D-''chiro''-inositol *

Ononitol Ononitol is a cyclitol. It is a 4-''O''-methyl-myo-inositol and is a constituent of ''Medicago sativa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an ...

; (1R,2S,3S,4S,5S,6S)-6-methoxycyclohexane-1,2,3,4,5-pentaol; 4-O-methyl-''myo''-inositol *

Pinpollitol Pinpollitol is a cyclitol. It is a di-''O''-methyl-(+)- chiro-inositol that can be isolated from ''Pinus radiata ''Pinus radiata'' ( syn. ''Pinus insignis''), the Monterey pine, insignis pine or radiata pine, is a species of pine native to t ...

; (1R,2R,3R,4S,5R,6S)-3,6-dimethoxycyclohexane-1,2,4,5-tetraol; di-O-methyl-(+)-''chiro''-inositol *

Quebrachitol Quebrachitol is a naturally occurring optically active cyclitol, a cyclic polyol. It can be found in ''Allophylus edulis'' and in the serum left after the coagulation of the ''Hevea brasiliensis'' latex in the operation of rubber tapping. It is al ...

; (1R,2S,4S,5R)-6-methoxycyclohexane-1,2,3,4,5-pentol; 2-0-methyl-''chiro''-inositol *

Quinic acid Quinic acid is a cyclitol, a cyclic polyol, and a cyclohexanecarboxylic acid. It is a colorless solid that can be extracted from plant sources. Quinic acid is implicated in the perceived acidity of coffee. Occurrence and preparation The compound ...

; (1S,3R,4S,5R)-1,3,4,5-tetrahydroxycyclohexanecarboxylic acid *

Shikimic acid Shikimic acid, more commonly known as its anionic form shikimate, is a cyclohexene, a cyclitol and a cyclohexanecarboxylic acid. It is an important biochemical metabolite in plants and microorganisms. Its name comes from the Japanese flower ''shik ...

; (3R,4S,5R)-3,4,5-trihydroxycyclohex-1-ene-1-carboxylic acid *

Valienol Valienol (streptol) is a C-7 cyclitol similar in structure to valienamine Valienamine is a C-7 aminocyclitol found as a substructure of pseudooligosaccharides such as the antidiabetic drug acarbose and the antibiotic validamycin. It can be fo ...

; (1S,2S,3S,4R)-5-(Hydroxymethyl)cyclohex-5-ene-1,2,3,4-tetrol *

Viscumitol Viscumitol is a cyclitol. It is a dimethyl-ether of ''muco''-inositol that can be isolated from ''Viscum album ''Viscum album'' is a species of mistletoe in the family Santalaceae, commonly known as European mistletoe, common mistletoe or si ...

(1R,2S,3R,4S,5R,6S)-5,6-dimethoxycyclohexane-1,2,3,4-tetraol; 1,2-di-O-methyl-''muco''-inositol

Glycosides

Ciceritol Ciceritol is a cyclitol. It is a pinitol digalactoside that can be isolated from seeds of chickpea, lentil The lentil (''Lens culinaris'' or ''Lens esculenta'') is an edible legume. It is an annual plant known for its lens-shaped seeds ...

, a pinitol digalactoside

Phosphates

* Phytic acid; (1R,2S,3r,4R,5S,6s)-cyclohexane-1,2,3,4,5,6-hexayl hexakis ihydrogen(phosphate) inositol hexakisphosphate

Other cyclitols

* 1,2,3,4-CyclohexanetetrolNihat Akbulut and Metin Balci (1988): "A new and stereospecific synthesis of cyclitols: (1,2,4/3)-, (1,2/3,4)-, and (1,3/2,4)-cyclohexanetetrols". ''Journal of Organic Chemistry'', volume 53, issue 14, pages 3338-3342. * 1,2,3,4,5-Cyclopentanepentol

Analysis methods

In 1955, Posternak and others described the separation of cyclitols by

paper chromatography Paper chromatography is an analytical method used to separate coloured chemicals or substances. It is now primarily used as a teaching tool, having been replaced in the laboratory by other chromatography methods such as thin-layer chromatography ...

in various solvents, and three methods of development:

Tollens reagent Tollens' reagent (chemical formula Ag(NH3)2OH) is a chemical reagent used to distinguish between aldehydes and ketones along with some alpha-hydroxy ketones which can tautomerize into aldehydes. The reagent consists of a solution of silver nitr ...

s, the Meillère reagent (based on the Scherer-Gallois reaction), and digestion by '' Acetobacter suboxydans'' followed by Tollens reagent.Th. Posternak, D. Reymond, W. Haerdi (1955): "Recherches dans la série des cyclitols XX. Chromatographie sur papier de cyclitols et de cycloses". ''Helvetica Chimica Acta'' volume 38, issue 1, pages 191-194

References

External links

List of cyclitol molecules on chemicalland21.com
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