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| Names | |
|---|---|
| IUPAC name D-Glucitol[1] | |
| Systematic IUPAC name (2S,3R,4R,5R)-Hexane-1,2,3,4,5,6-hexol | |
| Other names D-Sorbitol; Sorbogem; Sorbo | |
| Identifiers | |
| |
3D model (JSmol) | |
| ChEBI | |
| ChEMBL | |
| ChemSpider |
|
| DrugBank |
|
| ECHA InfoCard | 100.000.056 |
| E number | E420(thickeners, ...) |
| KEGG | |
| MeSH | Sorbitol |
| UNII | |
| |
| Properties | |
| C6H14O6 | |
| Molar mass | 182.17 g/mol |
| Appearance | White crystalline powder |
| Density | 1.49 g/cm3[2] |
| Melting point | 94–96 °C (201–205 °F; 367–369 K)[2] |
| 2350 g/L[2] | |
| logP | −4.67[3] |
| −107.80·10−6 cm3/mol | |
| Pharmacology | |
| A06AD18 (WHO) A06AG07 (WHO)B05CX02 (WHO)V04CC01 (WHO) | |
| Hazards | |
| NFPA 704 (fire diamond) | |
| Flash point | > 100 °C (212 °F; 373 K)[2] |
| 420 °C (788 °F; 693 K)[2] | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Sorbitol (/ˈsɔː(r)bɪtɒl/), less commonly known asglucitol (/ˈɡluːsɪtɒl/), is asugar alcohol with asweettaste which the human body metabolizes slowly. It can be obtained byreduction ofglucose, which changes the convertedaldehyde group (−CHO) to a primary alcohol group (−CH2OH). Most sorbitol is made frompotato starch, but it is also found in nature, for example in apples, pears, peaches, and prunes.[4] It is converted tofructose bysorbitol-6-phosphate 2-dehydrogenase. Sorbitol is anisomer ofmannitol, another sugar alcohol; the two differ only in the orientation of thehydroxyl group on carbon 2.[5] While similar, the two sugar alcohols have very different sources in nature,melting points, and uses.
As anover-the-counter drug, sorbitol is used as alaxative to treatconstipation.[6]
Sorbitol may be synthesised via a glucose reduction reaction[7] in which the convertedaldehyde group is converted into ahydroxyl group. The reaction requiresNADH and is catalyzed byaldose reductase. Glucose reduction is the first step of thepolyol pathway ofglucose metabolism, and is implicated in multiple diabetic complications.
The mechanism involves atyrosine residue in the active site of aldehyde reductase. The hydrogen atom on NADH is transferred to the electrophilic aldehyde carbon atom; electrons on the aldehyde carbon-oxygen double bond are transferred to the oxygen that abstracts the proton on tyrosine side chain to form the hydroxyl group. The role of aldehyde reductase tyrosine phenol group is to serve as a general acid to provide proton to the reduced aldehyde oxygen on glucose.
Glucose reduction is not the majorglucose metabolism pathway in a normal human body, where theglucose level is in the normal range. However, in diabetic patients whose blood glucose level is high, up to 1/3 of their glucose could go through the glucose reduction pathway. This will consume NADH and eventually leads to cell damage.
Sorbitol is asugar substitute, and when used in food it has theINS number andE number 420. Sorbitol is about 60% as sweet as sucrose (table sugar).[8]
Sorbitol is referred to as a nutritive sweetener because it provides some dietary energy. It is partly absorbed from the small intestine and metabolized in the body, and partly fermented in the large intestine. The fermentation producesshort-chain fatty acids,acetic acid,propionic acid, andbutyric acid, which are mostly absorbed and provide energy, but alsocarbon dioxide,methane, andhydrogen which do not provide energy. Even though theheat of combustion of sorbitol is higher than that of glucose (having two extra hydrogen atoms), the net energy contribution is between 2.5 and 3.4kilocalories pergram, versus the approximately 4 kilocalories (17 kilojoules) for carbohydrates.[9] It is often used indiet foods (including diet drinks and ice cream), mints,cough syrups, and sugar-freechewing gum.[10] Most bacteria cannot use sorbitol for energy, but it can be slowly fermented in the mouth byStreptococcus mutans, a bacterium that causestooth decay. In contrast, many other sugar alcohols such asisomalt andxylitol are considered non-acidogenic.[11][12]
It also occurs naturally in manystone fruits and berries from trees of the genusSorbus.[4][13]
As is the case with othersugar alcohols, foods containing sorbitol can causegastrointestinal distress. Sorbitol can be used as alaxative when taken orally or as anenema.[6] Sorbitol works as a laxative by drawing water into thelarge intestine, stimulatingbowel movements.[6][14] Sorbitol has been determined safe for use by the elderly, although it is not recommended without the advice of a physician.[6][15]
Sorbitol is commonly used orally as a one-time dose of 30–150 millilitres (1.1–5.3 imp fl oz; 1.0–5.1 US fl oz) 70% solution.[6] It may also be used as a one-timerectal enema.[6]
Sorbitol is used in bacterial culture media to distinguish the pathogenicEscherichia coli O157:H7 from most other strains ofE. coli, because it is usually unable to ferment sorbitol, unlike 93% of knownE. coli strains.[16]
A treatment forhyperkalaemia (elevated bloodpotassium) uses sorbitol and theion-exchange resinsodium polystyrene sulfonate (tradename Kayexalate).[17] The resin exchanges sodium ions for potassium ions in the bowel, while sorbitol helps to eliminate it. In 2010, the U.S.FDA issued a warning of increased risk for gastrointestinal necrosis with this combination.[18]
Sorbitol is also used in the manufacture ofsoftgel capsules to store single doses of liquid medicines.[19]
Sorbitol often is used in moderncosmetics as ahumectant andthickener.[20] It is also used inmouthwash andtoothpaste. Some transparentgels can be made only with sorbitol, because of its highrefractive index.
Sorbitol is used as acryoprotectant additive (mixed withsucrose and sodium polyphosphates) in the manufacture ofsurimi, a processed fish paste.[21] It is also used as a humectant in somecigarettes.[22]
Beyond its use as a sugar substitute in reduced-sugar foods, sorbitol is also used as a humectant in cookies and low-moisture foods like peanut butter and fruit preserves.[23] In baking, it is also valuable because it acts as aplasticizer, and slows down thestaling process.[23]
A mixture of sorbitol andpotassium nitrate has found some success as anamateur solidrocket fuel. It has similar performance to sucrose-basedrocket candy, but is easier to cast, less hygroscopic and does notcaramelize.[24]
Sorbitol is identified as a potential key chemical intermediate[25] for production of fuels frombiomass resources.Carbohydrate fractions in biomass such ascellulose undergo sequentialhydrolysis andhydrogenation in the presence of metal catalysts to produce sorbitol.[26] Complete reduction of sorbitol opens the way toalkanes, such ashexane, which can be used as abiofuel. Hydrogen required for this reaction can be produced by aqueous phasecatalytic reforming of sorbitol.[27]
The abovechemical reaction isexothermic, and 1.5moles of sorbitol generate approximately 1 mole ofhexane. When hydrogen is co-fed, nocarbon dioxide is produced.
Sorbitol based polyols are used in the production ofpolyurethane foam for the construction industry.
It is also added afterelectroporation of yeasts in transformation protocols, allowing the cells to recover by raising theosmolarity of the medium.
Aldose reductase is the first enzyme in thesorbitol-aldose reductase pathway[28] responsible for the reduction of glucose to sorbitol, as well as the reduction ofgalactose togalactitol. Too much sorbitol trapped in retinal cells, the cells of the lens, and theSchwann cells thatmyelinate peripheral nerves, is a frequent result of long-term hyperglycemia that accompanies poorly controlleddiabetes. This can damage these cells, leading toretinopathy,cataracts and peripheralneuropathy, respectively.
Sorbitol is fermented in the colon and produces short-chain fatty acids, which are beneficial to overall colon health.[29]
Sorbitol may causeallergic reactions in some people.[6] Common side effects from use as a laxative arestomach cramps, vomiting,diarrhea or rectal bleeding.[6]
The organism does not ferment sorbitol; whereas 93% of E. coli of human origin are sorbitol positive
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