Amadori rearrangement products

Knowledge about the chemical structure of the antioxidative MRP is very limited. Only a few attempts have been made to characterize them. Evans, et al. (12) demonstrated that pure reductones produced by the reaction between hexoses and secondary amines were effective in inhibiting oxidation of vegetable oils. The importance of reductones formed from amino acids and reducing sugars is, however, still obscure. Eichner (6) suggested that reductone-like compounds, 1,2-enaminols, formed from Amadori rearrangement products could be responsible for the antioxidative effect of MRP. The mechanism was claimed to involve inactivation of lipid hydroperoxides. 

Figure 44 Maillard reaction of lactose and fluoxetine HCI yielding major degradants glycosylamine, Amadori rearrangement product, and N-formyl fluoxetine.

Tjan SB, van den Ouweland GAM. PMR investigation into the structure of some N-substituted 1-amino-1-deoxy-D-fructoses (Amadori rearrangement products). Tetrahedron 1974 30 2891-2897. 

When the structure of a compound is known, the current British-Ameri-can practice42 will be followed. No specific recommendation was made for naming Amadori rearrangement products, but, under Rule 8, the systematic name for the Amadori product of JV-i>-glucosyl-DL-leucine could be 1-(dl-l-carboxy-3-methylbutyl)amino-l-deoxy-D-fructose (I or II), and this name conflicts with the requirement that the carboxyl function takes precedence and that the name should end in acid. Consequently, this compound should be named as N- (n-ara zno-tetrahydroxy-2-oxohexyl)-DL-leucine. A shorter and equally unambiguous name would be l-(DL-leucino)-l-deoxy-D-fructose. (This is sometimes shortened to DL-leucino-deoxyfructose. Such compounds have also been called fructose-leucine, but this is not recommended since it may be confused with such expressions as the fructose-leucine system.11)... 

The intermediate endiol structures give rise to a facile sugar decomposition by which different aliphatic or cyclic mono- or dicarbonyl compounds are formed. For Amadori rearrangement products two reaction pathways are known the 1-deoxy or the 3-deoxyosone pathways. 

This article describes a study on the catalytic role of phosphate in the Maillard reaction focussing on the first steps of the cascade of reactions, i.e. the conversion of the starting materials, monosaccharide and glycine, into the so-called Amadori Rearrangement Product (ARP). 

The influence of inorganic phosphate and the pH on the concentration of the Amadori Rearrangement Product. 

Additionally the conversion of the Amadori Rearrangement Product is enhanced, resulting in the increased formation of reaction products, which are the actual flavour materials. The highest yields of ARP based on the starting materials were therefore obtained in the absence of phosphate. 

Figure 1. Different possible structures for an Amadori rearrangement product.

V. A. Yaylayan and A. Huyghues-Despointes, Chemistry of Amadori rearrangement products Analysis, synthesis, kinetics, reactions, and spectroscopic properties, CRC Crit. Rev. Food Sci. Nutr., 1994, 34, 321-369. 

A group of compounds which may be considered the Amadori rearrangement products of N-glucosylamino acids give firm complexes with... 

The conversion of anthranilic acid to tryptophan by cell-free extracts involves, initially, a reaction with 5-0-phospho-a-D-ribosyl pyrophosphate (XX, see Fig. 8). On the basis of the known enzymic reactions of XX, the formation of X-(o-carboxyphenyl)- 9-D-ribofuranosylamine 5-phosphate (XXI) would be expected. However, the first identifiable compound is the unphosphorylated, Amadori-rearrangement product XXII which is formed... 

The formation of the pyridinol is prevented if, in the step 19 to 20, no anion can be eliminated from C-3 this is the case with 5-amino-3,5-dideoxy-l,2-0-isopropylidene-a-D-er /thro-pentofuranose, which, on acid hydrolysis, afFords only the Amadori rearrangement product and no pyridine derivative. The reaction then proceeds, according to the above mechanism, in only one direction from 19. The 3-deoxypentose is prepared, in a manner analogous to the formation of 15, from 3-deoxy-l,2-0-isopropylidene-a-D-riho-hexofuranose through catalytic reduction of the phenylhydrazone of its periodate-oxidation product. ... 

Cold barium hydroxide quantitatively removes the sulfite group from 25 and 26. The 5-amino-5-deoxy-D-xylose so liberated exists mainly in the form 17. Only in alkaline solution is it relatively stable toward acids it is extremely sensitive. Compound 17 accordingly behaves fundamentally differently from all other monosaccharides. In neutral solution (obtained by neutralization of its solution in barium hydroxide with carbon dioxide), the Amadori rearrangement product (22) is formed on standing at room temperature. With hydrochloric acid, 22 is likewise formed as the major product, together with 3-pyridinol (21). Free 17 cannot be isolated in pure form the product obtained contains 16 and 22 in proportions that vary with the pH of the evaporated solution. The impurities are lowest at pH 9.6. It is reported that, from the evaporated solution of 17, a 96 % yield of 25 can be recovered, but it should be mentioned that 16 and 22 also react with sulfurous acid to form 25 and 29. Thin-layer chromatograms (silica gel with p-dioxane—water) always show, besides 17, spots for the secondarily formed 16 and 22. 

Cotton efiFect. The most favorable conformation, as with 33, should exhibit a negative efiFect. No explanation of this anomaly can as yet be given. Solutions of 5-amino-3,5-dideoxy-D-ery thro-pentose in water brown rapidly, and only the Amadori rearrangement product can be detected therein. ... 

Another equilibrium partner of the form 102a is the cyclic Schiff base 101a, formed by dehydration. The C=N chromophore in 101a exhibits a weakly positive Cotton effect at 250 nm, by which the proportion of 101a present can be demonstrated. The Cotton effect disappears at pH values below 6. By comparison with 5-amino-5-deoxy-D-xylopyranose (17), 102a is definitely the more stable toward acids. Neither an Amadori rearrangement product, nor aromatization to a p)nTole derivative, is observed down to pH 1.0. 

VIII. Proof of Structure of Amadori Rearrangement Products. 199... 

The usefulness of the Amadori rearrangement in chemical synthesis was demonstrated by Weygand who showed how n-arabinose, instead of the more expensive n-ribose, could be used in the preparation of riboflavin. Condensation of n-arabinose with 3,4-dimethylaniline in the presence of an acid catalyst gave the Amadori rearrangement product, 1-deoxy-l-(3,4-dimethylanilino)-D-er2/ liro-pentulose (not isolated), which could be catalytically hydrogenated in alkaline solution to produce the desired intermediate, l-deoxy-l-(3,4-dimethylanilino)-D-ribitol. Also, Amadori re-... 

The American-British Committee on Carbohydrate Nomenclature also recommends an alphabetical order of the prefixes, including the deoxy prefix. According to the Rules, complete names for two hypothetical Amadori rearrangement products would be.l-deoxy-l-piperidino-a-D-fruc-tofuranose and l-benzylamino-l-deoxy- 3-D-tagatopyranose. 

An Amadori rearrangement product apparently was formed in the reaction of 3-C-phenylglyceraldehyde with V-methylaniline in dry ethanol-acetic acid solution as conducted by Smith and Anderson. A white, crystalline l-deoxy-l-(V-methylanilino)-3-C-phenylketose, C6H6(CH3)N C3H402-C6H6, was isolated. Whether the carbonyl group (the. compound... 

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