Polyhydric alcohols mannitol

Osmotic laxative effects are also produced by the polyhydric alcohols, mannitol and sorbitol, which unlike glucose cannot be transported through the intestinal mucosa, as well as by the non-hydrolyzable disaccharide, lactubse. Fermentation of lactulose by colon bacteria results in acidification of bowel contents and microfloral damage. Lactulose is used in hepatic failure in order to prevent bacterial production of ammonia and its subsequent absorption (absorbable NH3 nonabsorbable NH4+), so as to forestall hepatic coma. 

Osmotic laxative effects are also produced by the polyhydric alcohols mannitol and sorbitol, which unlike glucose cannot be transported through the intestinal mucosa. 

Humectants. In certain foods, it is necessary to control the amount of water that enters or exits the product. It is for this purpose that humectants are employed. Polyhydric alcohols (polyols), which include propylene glycol [57-55-6], C2Hg02, glycerol [56-81-5], C HgO, sorbitol [50-70-4], and mannitol [69-65-8], contain numerous hydroxyl groups (see Alcohols,polyhydric). Their stmcture makes them hydrophilic and... 

Its acidity is considerably enhanced by chelation with polyhydric alcohols (e.g. glycerol, mannitol) and this forms the basis of its use in analytical chemistry e.g. with mannitol p T drops to 5.15,... 

Mannitol hexanitrate is obtained by nitration of mannitol with mixed nitric and sulfuric acids. Similarly, nitration of sorbitol using mixed acid produces the hexanitrate when the reaction is conducted at 0—3°C and at —10 to —75°C, the main product is sorbitol pentanitrate (117). Xylitol, ribitol, and L-arabinitol are converted to the pentanitrates by fuming nitric acid and acetic anhydride (118). Phosphate esters of sugar alcohols are obtained by the action of phosphorus oxychloride (119) and by alcoholysis of organic phosphates (120). The 1,6-dibenzene sulfonate of D-mannitol is obtained by the action of benzene sulfonyl chloride in pyridine at 0°C (121). To obtain 1,6-dimethanesulfonyl-D-mannitol free from anhydrides and other by-products, after similar sulfonation with methane sulfonyl chloride and pyridine the remaining hydroxyl groups are acetylated with acetic anhydride and the insoluble acetyl derivative is separated, followed by deacetylation with hydrogen chloride in methanol (122). Alkyl sulfate esters of polyhydric alcohols result from the action of sulfur trioxide—trialkyl phosphates as in the reaction of sorbitol at 34—40°C with sulfur trioxide—triethyl phosphate to form sorbitol hexa(ethylsulfate) (123). 

The reactions of peroxyl radicals derived from polyhydric alcohols were studied by using flash photolysis of H202 as the radiomimetic system,116 and by various product studies on ethylene glycol,148,149 glycerol,149 erythritol,145 D-arabinitol,149 D-mannitol,148,149 D-glu-citol,145,150,151 myo-inositol,147,152-154 and scyMo-inositol.77... 

Figure 13.18 shows the effect of sorbitol. Agradual decrease in the CP with an increase in sorbitol concentration was observed. Some other polyhydric alcohols (including saccharides, viz. mannitol, glucose, sucrose, fructose, etc.) induced a similar decrease. A decrease in CP with saccharides has been observed for polyethylene glycol (PEG) and for sorbitol on polysorbate, a nonionic surfactant (Zatz and Lue, 1987 Attwood et al., 1989). Sjoberg et al. (1989) showed that all saccharides decrease the CP of PEG, which is well described by mean Leld theory. Also, an explanation was given for the difference between the saccharides in their ability to decrease the CP in aqueous PEG solutions. 

These treatments convert to ionic substances, and remove, nearly all constituents of natural materials the acid treatments release any inositol present as phosphate, or combined in phospholipids, glycosides, etc. Glycerol remains in the deionized sample, but it can be oxidized separately, or be removed by heat decomposition or by repeatedly evaporating the solution to dryness. Such polyhydric alcohols of greater chain length as erythritol and mannitol, when present, would still interfere. However, corrections can be made for these compounds by determining the formaldehyde which they form on periodate oxidation, or they may be removed by chromatography on filter paper. The micro-periodate method is well suited to the analysis of samples eluted from filter paper, provided that care is exercised to remove the tiny particles of cellulose which are usually found in such eluates. 

Sorbitol Solution occurs as a clear, colorless, syrupy liquid. It is a water solution of sorbitol (C6H1406) containing a small amount of mannitol and other isomeric polyhydric alcohols. It is miscible with water, with ethanol, with glycerin, and with propylene glycol. It sometimes separates into crystalline masses. 

These include mannitol and sorbitol which act mainly in the proximal tubules to prevent reabsorption of water. These polyhydric alcohols cannot be absorbed and therefore bind a corresponding volume of water. Since body cells lack transport mechanisms for these substances (structure on p.175), they also cannot be absorbed through the intestinal epithelium and thus need to be given by intravenous infusion. The result of osmotic diuresis is a large volume of dilute urine, as in decompensated diabetes melli-tus. Osmotic diuretics are indicated in the prophylaxis of renal hypovolemic failure, the mobilization of brain edema, and the treatment of acute glaucoma attacks (p. 346). 

Isotope effects have also been observed in whole cells. Acetobacter suboxydans selectively oxidizes polyhydric alcohols having a specific pattern of hydroxyl groups. It oxidizes D-mannitol at C-2 and C-5. When D-mannitol-I-t, D-mannitol-2-t, and D-mannitol-3-t are oxidized to D-ffuctose, the unlabeled half of the molecule is oxidized the more rapidly. This result was attributed188 to a primary isotope-effect at C-3, and a secondary isotope-effect at C-2. 

From these findings with triols, it follows that, apart from the expectation that formation of five- and six-membered rings would be favored (see, however, the exceptional compound 19), no general conclusions can be drawn regarding the structures of boronates derived from more-complex polyhydric alcohols. In Table V, alditol boronates are listed with structures when these can be concluded either from the method of synthesis, from physical studies, or by deduction (as with the 1,2 5,6-diesters formed from 3,4-di-O-substi-tuted mannitols). 

Esterification of fatty acids and polyhydric alcohols The reaction of fatty acids with polyhydroxy compounds, such as ethylene glycol or glycerol, yields monoglycerides or polyglycerides. Prominent members of the higher polyol series, for example, include sorbitol and mannitol. 

Polyhydric alcohols include xylitol, mannitol, sorbitol, maltitol, lactitol and isomalt. Although these products generally have a lower sweetening power than sucrose, they also have fewer calories, only 2.4 kilocalories per gram of dry matter. They also do not cause tooth decay, and for this reason are mainly used in anti-cariogenic chewing gum and confectionaries. However, polyhydric alcohols also have an undesirable laxative effect that becomes apparent with excess consumption and as a function of individual constitution. Eor this reason, the European Union does not allow the beverage industry to use polyhydric alcohols as a sweetener. 

Polyhydric Alcohol Sorbitol Mannitol Glycerin Sucrose Glucose... 

Polyhydric alcohols, e.g., mannitol Stabilisation, bulking agent... 

Parenteral formulations often contain excipients considered to be chemically stable and inert however, all excipients in a formulation may influence the photochemical stability of the product. Dextrose and sodium chloride are used to adjust tonicity in the majority of parenteral formulations. Sodium chloride can affect photochemical processes by influencing solvation of the photoreactive molecules (see Section 14.2.3). The ionic strength is reported to affect the photochemical decomposition rate of minoxidil until a saturation level is reached (Chinnian and Asker, 1996). The photostability of L-ascorbic acid (vitamin C) in aqueous solution is enhanced in the presence of dextrose, probably caused by the scavenging effect of the excipient on hydroxyl radicals mediated by the photolysis of ascorbic acid sucrose, sorbitol, and mannitol have the same effect (Ho et al., 1994). Monosaccharides (dextrose, glucose, maltose, and lactose), disaccharides (sucrose and trehalose), and polyhydric alcohols (inositol, mannitol, and sorbitol) are examples of commonly used lyo-additives in parenterals. These excipients may also affect photochemical stability of the products after reconstitution. 

In order to better understand the nucleophilicity of carbohydrates and polyhydric alcohols, the reactivities of dextrose, sucrose, sorbitol, and mannitol with a few simple p-nitrophenyl esters were studied at 25 °C and ionic strength 1.0 (KCl) in aqueous solution. 

Based on die pH dependency of die catalytic rate constants, die reactivity of die polyhydric alcohols was attributed to die anion derived from ionization of a hydroxy group in die polyhydric alcohol. The second-order rate constants representing die nucleophilic reactivity of die polyhydric alcohol anions were determined. Results diowed diat die nucleophilic reactivity of dextrose, sucrose, sorbitol and mannitol is similar to other alcohols of comparable pl<. .."... 

Fungi have characteristic soluble carbohydrates (the disaccharide trehalose and polyhydric alcohols like mannitol and arabitol) and storage compounds (e.g. glycogen), differing from those of most plants and animals. 

Glucose, sucrose, and polyhydric alcohols, glycerol, sorbitol, and mannitol, display nucleophilic reactivity with simple activated esters in aqueous solution buffered at neutral to alkaline pH. This nu-cleophylic reactivity is attributed to the anion resulting from ionization of a hydroxyl group. These polyhydric alcohols have been shown to be catalyt-ically active in the hydrolysis of cephalosporins in... 

Apart from lipids based on phosphate esters of glycerol (10.52a), there has been comparatively little investigation of the corresponding derivatives of the other polyhydric alcohols (10.52b). Of special interest are alcohols of the ribitol ( = 3) or mannitol (n = 4) type which bear a close relationship to the naturally occurring saccharides. There is already a rapidly emerging chemistry of the glycolipids (below). 

Simple sugars can be reduced to polyhydric alcohols for example, glucose yields sorbitol, galactose yields dulcitol, and both mannose and fructose yield mannitol. Mannitol occurs in grass silage and is formed by the action of certain anaerobic bacteria on the fructose present in the grass. ... 

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