{{Short description|Class of chemical compounds}} [[File:Myo-inositol numbering.svg|220px|thumb|right|[[inositol]] is a common cyclitol.]] In [[organic chemistry]], a '''cyclitol''' is a [[cycloalkane]] containing at least three [[hydroxyl]], each attached to a different ring carbon atom.<ref>{{GoldBookRef|title=Cyclitols|file=C01493|doi=10.1351/goldbook.C01493 }}</ref> Most commonly, cyclitol refers to cyclic [[sugar alcohol]].<ref name="Vovener de Verlands et al 2025">{{cite journal |last1=Vovener de Verlands |first1=Edmond |last2=Hong |first2=Zonglie |last3=Nelson |first3=Andrew S. |title=Sugar alcohols in plants: implications for enhancing tree seedlings drought tolerance and production strategies |journal=BMC Plant Biology |date=2025 |volume=28 |issue=1 |article-number=891 |doi=10.1186/s12870-025-06860-9 |pmid=40634904 |pmc=12239448 |bibcode=2025BMCPB..25..891E |doi-access=free }}</ref> Cyclitols and their derivatives are some of the [[osmoprotectant|compatible solutes]] that are formed in a plant as a response to salt or water stress. Cyclitols are minor components of trees.<ref>{{cite journal |last1=Hoch |first1=G. |last2=Richter |first2=A. |last3=Körner |first3=Ch. |title=Non-structural carbon compounds in temperate forest trees |journal=Plant, Cell & Environment |date=2003 |volume=26 |issue=7 |pages=1067–1081 |doi=10.1046/j.0016-8025.2003.01032.x |bibcode=2003PCEnv..26.1067H }}</ref> Some cyclitols (e.g. [[quinic acid|quinic]] or [[shikimic acid]]) are parts of [[hydrolysable tannin]]s.
Even simple cyclitols can be complicated by different [[isomer]]ic possibilies. For example, there are three different [[constitutional isomer]]s of cyclohexanetriol: 1,2,3-, 1,2,4-, and 1,3,5-. And even though there is only one reasonably stable constitutional isomer of cyclohexanehexol ([[inositol]]), there are nine [[stereoisomer]]s possible.
==Naturally occurring cyclitols== ===Unsubstituted=== * [[Conduritol]], or cyclohex-5-ene-1,2,3,4-tetrol; two out of ten possible isomers. * [[Inositol]], or cyclohexane-1,2,3,4,5,6-hexol; four out of nine possible isomers. * [[Cyclohexanetetrol]]<ref name=craig1969>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. {{doi|10.1139/f69-282}}</ref>
===Substituted=== * [[Bornesitol]]; (1R,2R,3S,4S,5R,6S)-6-methoxycyclohexane-1,2,3,4,5-pentol; D-(−)-O-methyl-''myo''-inositol * [[Pinitol]]; (1S,2S,4S,5R)-6-methoxycyclohexane-1,2,3,4,5-pentol; 3-O-methyl-D-''chiro''-inositol * [[Ononitol]]; (1R,2S,3S,4S,5S,6S)-6-methoxycyclohexane-1,2,3,4,5-pentaol; 4-O-methyl-''myo''-inositol * [[Pinpollitol]]; (1R,2R,3R,4S,5R,6S)-3,6-dimethoxycyclohexane-1,2,4,5-tetraol; di-O-methyl-(+)-''chiro''-inositol * [[Quebrachitol]]; (1R,2S,4S,5R)-6-methoxycyclohexane-1,2,3,4,5-pentol; 2-0-methyl-''chiro''-inositol * [[Quinic acid]]; (1S,3R,4S,5R)-1,3,4,5-tetrahydroxycyclohexanecarboxylic acid * [[Shikimic acid]]; (3R,4S,5R)-3,4,5-trihydroxycyclohex-1-ene-1-carboxylic acid * [[Valienol]]; (1S,2S,3S,4R)-5-(Hydroxymethyl)cyclohex-5-ene-1,2,3,4-tetrol * [[Viscumitol]] (1R,2S,3R,4S,5R,6S)-5,6-dimethoxycyclohexane-1,2,3,4-tetraol; 1,2-di-O-methyl-''muco''-inositol
===Glycosides=== * [[Ciceritol]], a pinitol digalactoside
===Phosphates=== * [[Phytic acid]]; (1R,2S,3r,4R,5S,6s)-cyclohexane-1,2,3,4,5,6-hexayl hexakis[dihydrogen(phosphate)]; inositol hexakisphosphate
===Other cyclitols=== * [[1,2,3,4-Cyclohexanetetrol]]<ref name=akbu1988>Nihat 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. {{doi|10.1021/jo00249a039}}</ref> * [[1,2,3,4,5-Cyclopentanepentol]]
==Applications== Aside from their utility to plants, cyclitols are useful as precursors to synthetic materials.<ref>{{cite journal |last1=Ferrier |first1=Robert J. |last2=Middleton |first2=Sydney |title=The conversion of carbohydrate derivatives into functionalized cyclohexanes and cyclopentanes |journal=Chemical Reviews |date=1993 |volume=93 |issue=8 |pages=2779–2831 |doi=10.1021/cr00024a008}}</ref>
==Analysis methods== Théodore Posternak and others described the separation of cyclitols by [[paper chromatography]] using three methods of development: [[Tollens' reagent]]s, the [[Meillère reagent]] (based on the [[Scherer-Gallois reaction]]), and digestion by ''[[Acetobacter suboxydans]]'' followed by Tollens' reagent.<ref name=post1955a>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 {{doi|10.1002/hlca.19550380122}}</ref>
==Further reading== 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. {{doi|10.1111/j.1432-1033.1968.tb00328.x}}
==See also== * [[Aminocyclitol]]
==References== {{reflist}}
==External links== {{wiktionary|cyclitol}}
{{Authority control}}
[[Category:Cyclitols| ]]