Synthetic Sugars

We will start by presenting new advances from the NMR methodological viewpoint to later describe some key examples of applications of NMR for sugar conformation determination, by discriminating between the free and bound state and also from natural and synthetic sugars (or mimetics thereof). 

The value of pharmacological interventions is not as firmly established as is desirable. Control of pre-cipitants notably gastrointestinal haemorrhage, systemic infection, constipation and electrolyte, particularly potassium imbalance is important. Despite lack of consistent evidence, use of synthetic sugars by mouth and oral antibiotics (neomycin or metronidazole) remains standard. Oral neomycin, though poorly absorbed, can still cause eighth cranial nerve damage. 

Bols and co-workers [61] synthesized isofagomine (23), a compound in which the basic hetero-atom replaces the anomeric carbon, and showed that this new type of synthetic sugar analogue is one of the strongest inhibitors of -glucosi-dase from almonds known to date. Following this innovative work, Ichikawa and Ichikawa prepared (3i ,4 ,511)-3(] )-hydroxymethylpiperidine (l,5-dideoxy-2-C-hydroxymethyl-l,5-imino-D-arabinitol, 24) [62] from D-lyxose. This was... 

The first, total synthesis of sugar-like compounds was performed as early as 1861 in that year, Butlerov2 reported the formation of methylenitan on treatment of aqueous formaldehyde with calcium hydroxide. The first, defined sugar derivative, DL-mannitol ( a-acrit ), was obtained by Emil Fischer and Tafel,3 and the first, optically active, totally synthetic sugars, D- and L-mannose and D- and L-fructose, were also prepared by Fischer.4... 

Lactitol. Lactitol (4-0-/ -D-galactopyranosyl-D-sorbitol), is a synthetic sugar alcohol produced on reduction of lactose, usually using Raney nickel. It can be crystallized as a mono- or di-hydrate. Lactitol is not metabolized by higher animals it is relatively sweet and hence has potential as a non-nutritive sweetener. It is claimed that lactitol reduces the absorption of sucrose, blood and liver cholesterol levels and to be anticariogenic. It has applications in low-calorie foods (jams, marmalade, chocolate, baked goods) it is non-hygroscopic and can be used to coat moisture-sensitive foods, e.g. sweets. 

A new class of synthetic sugar-protein conjugates has been introduced to circumvent this problem.126 An aldonic acid was joined, through peptide bonds, to a protein, and the product was used for screening and specificity studies. 

The synthetic sugar substrate is colourless but the p-nitrophenol is formed as the green-yellow coloured p-nitrophenate anion that has an absorption maximum at about 400 nm. Similar assay procedures can be used to determine nuclease activity with DNase I ... 

Avery OT, Goebel WE. Chemo-immunological studies on conjugated carbohydrate-proteins. II. Immunological specificity of synthetic sugar-protein antigens. J. Experim. Med. 1929 50 533— 550. 

A wide variety of synthetic sugar and nucleoside mimicking compounds with sulfur in the ring have been prepared for basic research, with a view to producing biologically active compounds with improved biochemical properties. Various classes of compounds are discussed in the following paragraphs. 

Neutral synthetic sugar derivatives, for example SM-5887 (39), display good antitumor activity with reduction in local tissue toxicity and cardiotoxicity compared to, for example, adriamycin (35) [51],... 

Scheme 2. ENGase-catalyzed transglycosylation with synthetic sugar oxazolines... 

Figure 5. Structures of additional synthetic sugar oxazoline derivatives...

A few members of a new class of synthetic sugar molecules called neoglycopolymers can perform this trick, causing L-selectin molecules on meandering cells first to cluster and then to fall off cell surfaces. Neoglycopolymers are simple to make and halt inflammatory processes in a distinctly different way than do existing anti-inflammatory drugs, such as aspirin or ibuprofen. While these medicines block... 

Dowex-50 resin) 2.4. The chromatographic and electrophoretic properties of the synthetic sugar were identical with those of pneumosamine hydrochloride, and the infrared spectrum (Nujol mull) of the synthetic sugar was consistent with the proposed structure. This evidence established that the sugar was enantiomorphous with pneumosamine hydrochloride. 

Pigman WW. Action of almond emulsion on the phenyl glycosides of synthetic sugars and on p-thiophenyl-r/-glucoside. J Res Natl Bur Stand 1941 26 197-204. 

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