Trehalose oxidation

Similar instances, in which analytical data were of prime importance and where no products were isolated, are the oxidations of various di-D-fructose dianhydrides,80 inositols,81 the trisaccharide moiety of the alkaloid solamargine,82 2-O-a-L-fucopyranosyl-L-fucitol derived from fucoidin83 (a polysaccharide sulfate ester), trehalose and neotrehalose,84 maltotetraose,85 D-galactopyranosyl-glyceritol,86 and a 3-pentulose.87... 

The reaction of these aldehydes, derived from periodate oxidation, with carbonyl reagents has also been investigated. Studies 147 148 were made on oxidized laminarin, a (1 —> 3)-linked polysaccharide, in which only the terminal residues had been oxidized. The addition of phenylhydrazine acetate detached the remainder of the terminal residue as glyoxal phenyl-osazone. When the aldehydic compounds derived from the periodate oxidation of raffinose and trehalose818a were reacted with p-nitrophenylhydrazine, the authors were surprised to find that one molecule of oxidized raffinose, containing six aldehydic functions, reacts with only three molecules of the reagent, and that the four aldehydic functions of the oxidized trehalose molecule react with only two. The reactions of periodate-oxidized carbo-... 

Very successful experiments were carried out on the oxidation of sucrose, one mole of which needs three moles of periodic acid, with the formation of one mole each of formic acid and a tetraaldehyde. The latter is oxidized by bromine to a tetracarboxylic acid subsequent acid hydrolysis of the oxygen bridges affords a mixture of acids, all of which were isolated and identified. These results brought in 1943 a confirmation of the structure of sucrose which was discussed, and which gained the approval of C. S. Hudson who, before that, was a little doubtful about the furanoid form of the D-fructosyl group. Similar work was done later with trehalose. In the same way, J. . Courtois obtained confirmation of the structure of raffinose, and established that of stachyose. 

In the a approach by Mombarg et a/.,[59] oxidation of disaccharides, such as trehalose and sucrose (25 mmol), was performed in 25 ml of water at 70 °C, with 100 mg of Ti-MCM-41 (7.2 pmol of Ti) and 25 g of 35 wt% H2O2, at pH = 4. After 20 h of reaction, a deep oxidation is observed leading to C1-C4 mono- and dicarboxylic acids, formic acid, glycolic acid, tartronic acid and tartaric acid. The absence of selectivity is then a major drawback compared with other oxidation processes, but another drawback was identified with Ti leaching from the molecular sieve framework. 

Trehalose is able to stabilize biological structures in a dehydrated form, and to make them intact and functional as soon as the hydration and temperature conditions return to normal. Thus, it behaves as a chemical chaperone in desiccation stress. Additionally, trehalose acts as a protectant against other environmental stresses such as freezing [4,5], osmotic shock [6], oxidation [7-9],... 

A speculative biosynthetic pathway for trehazolin (2) has been proposed,42 as shown in Scheme 1. Two molecules of the glucosylamine (i) could react with carbon dioxide to give the carbodiimide ii, which could be transformed into iii. Subsequent regioselective oxidation to iv, followed by a stereoselective pinacol-type coupling could afford trehazolin (2). The biosynthesis of trehalose has also been the subject of several subsequent chapters.43-48... 

More drastic conditions were used with iodic acid, high temperatures and strongly acid solutions being employed. The oxidation products w ere not isolated. Williams and Woodsused 35% sulfuric acid containing 1% potassium iodate, the sugar being heated for ninety minutes at 100° with this oxidant. Ketoses, sucrose and pentoses were attacked, but L-rhamnose was oxidized more slowly. It was remarkable that none of the aldohexoses or lactose vere detectably oxidized. The reactions of cellobiose and trehalose were ascribed to impurities. 

Fig. 13 Chemical degradation in freeze dried hGH formulated with trehalose as a function of water content at 40 C and 50°C. The pseudo first-order rate constant for degradation (%/month) is given for the combination of asparagine deamidation and methionine oxidation. The formulation is hGH trehalose in a 1 6 weight ratio with sodium phosphate buffer (pH 7.4) at 15% of the hGH content. The highest moisture content samples were collapsed after storage at both 40°C (moderate collapse) and 50°C (severe collapse). The water content that reduces the glass transition temperature of the formulation to the storage temperature is denoted Wg. O = 40°C storage = 50°C storage. (From Ref. l)...

Red-Al) or the Z-olefin 341 after benzylation. Stereoselective dihydroxylation and regiose-lective protection of the diol provides protected polyol 342 that is transformed in three steps to terminal epoxide 343. Removal of the p-methoxybenzyl group followed by acid-catalyzed epoxide opening yields exclusively tetrahydropyran 344 after protection of the primary alcohol and deacetylation. Inversion of the C2 stereocenter by an oxidation-reduction sequence and deprotection furnishes the C-mimic of a,a-trehalose 345. 

Trehalose is incompatible with strong oxidizing agents, especially in the presence of heat. 

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