Vitamin from sorbitol

AI3-19425 EINECS 201-771-8 Esorben HSDB 780 NSC 97195 L-1,2,3,4,5,6-Pentahydroxyhexan-2-one Sorbin Sorbinose L-Sorbinose Sorbose Sorbose, L- L-Sorbose l-Sorbose L-xylo-2-Hexulose. Made from sorbitol (itself made by reduction of glucose) by fermentation and used in the manutxture of ascorbic acid (vitamin C). mp = 165° [a)8°= -43.2° (c = 6) soluble in H2O, insoluble in organic solvents. 

Many vitamins of medical importance can be synthesized by microorganisms. However, only two and a half vitamins are now produced by fermentation. Vitamin B2 (riboflavin) and vitamin B12 (cyanocobalamin) are products of fermentation. The remaining half vitamin produced by fermentation is vitamin C. L-Sorbose is the precursor of vitamin C (ascorbic acid), and L-sorbose is produced mirobiologically from sorbitol. 

Vitamin C is also able to protect the hypothalamus from oxidative stress induced in rats by an environmental toxicant (Muthuvel et al., 2006). Ascorbic acid confers protection from increased free-radical activity in the brain of spontaneously hypertensive rats by improving total antioxidant and superoxide dismutase status, thus preventing high blood pressure and its complications (Newaz et al., 2005). Also, intravenous cerebroprotective doses of citrate/sorbitol-stabilized DHA are correlated with increased brain ascorbate levels and a suppression of excessive lipid peroxidation (Mack et al., 2006). 

These are just a few of the many chemical reactions of the hexoses. Gluconic acid, glucono-5-lactone from this acid, sorbitol, sorbitol esters, sorbitans (tetra-hydric anhydrosorbitol), mannitol, mannitol esters, copolymers of fatty acid sorbitol esters and alkylene oxides, and a few other derivatives are currently marketed as commodity chemicals derived from the hexoses. Vitamin C (l-ascorbic acid) is perhaps one of the best examples of a commercial derivative of D-glucose that is manufactured primarily by chemical synthesis ... 

Among the pentoses, D-xylose is the cheapest and is readily accessible from wood- or straw-derived xylans. L-Sorbose is the most readily available L-sugar on a large scale due to its technological accessibility from D-sorbitol in the vitamin C industrial production process. 

Synthesis of Ascorbic acid and of Disaccharides (i) The synthesis of Vitamin C (75), ascorbic acid from D-galactose (ref.72) and that from D-glucose (ref.73) were described in the same year which also saw the development of the the latter as an industrial route. Sorbitol obtained by the reduction of D-glucose was oxidised with the bacterium Acetobacter suboxvdans to L-sorbose which as the bis-acetonylidene derivative was next oxidised to the corresponding acid, L-2-oxogulonic acid, the methyl ester of which was base-catalysed to afford the final product as illustrated. 

L-Aseorbie acid (9), or vitamin C, is produced at large scale by the Reichstein-Grussner process, which dates back to the 1920s (Scheme 7) [33], It involves the enzymatic oxidation of n-sorbitol (8) that is, in turn, obtained from D-glucose (see 5.3.2). 

An alternative surfactant combination which is free of ethoxylated molecules is based on rapeseed sorbitol ester and sodium lauroyl glutamate [53]. Here, the phase inversion from a w/o- to an o/w-emulsion can be initiated by the addition of lauroyl glutamate, which is a hydrophilic surfactant, instead of using the temperature. Penetration studies for the release of Vitamin E from PIT emulsions in comparison with other formulation concepts have been performed [54]. It has been shown that the penetration of Vitamin E into the skin is better for a w/o-cream than a PIT emulsion. The free diffusion of Vitamin E might be hindered by the oil-water interface, which acts as a barrier around the oil droplets. 

Many stereo- and regioselective redox reactions have been carried out on a preparative scale by the catalysis of enzymes or microorganisms. The majority of these reactions involves the reduction of keto groups to chiral secondary alcohols or derivatives thereof Not only the reductions of CX-double bonds, but also selective dehydrogenations are of interest. A well-known example of a regioselective biocatalytic dehydrogenation is the formation of L-sorbose from D-sorbitol which is actually the key step in the synthesis of vitamin C. 

The current revival of interest in the relationship between dietary carbohydrate and vitamin requirements stems from the observations that rats grow and thrive without thiamine if their food contains sorbitol (Morgan and Yudkin, 1957). The problem which was being investigated was one of metabolism, but the answer, as we shall see, has little if anything to do with this. 

It is fairly certain, however, that increased absorption c.aiinot play any more than a very minor part in the sparing effect of sorbitol on thiamine reported by Morgan and Yudkin (1957). We believe that this effect is due to microbial synthesis of the vitamins in the gut, and Chow and his co-workers (Okuda et al., 1960) now agree to this. We shall examine the evidence for this in some detail later. The simplest and most conclusive evidence that enhancied absorption is not the explanation is that the effect occurs with diets entirely free from thiamine. In these circumstances, there is no dietary thiamine the absorption of which could be enhanced by sorbitol. The same... 

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