Formation from Amadori compound with

Formation of Glucosone from Amadori Compound with Copper Ion... 

It appears that both JL, and 3 are produced as intermediates during the decomposition of an Amadori compound. There is little evidence, based on end product isolation that the 4-deoxyosone (2) is produced to any extent in these reactions. An early isolation of 1, by Anet (6), was accomplished by decomposing an Amadori compound ("difructose glycine") in aqueous solution. Subsequent studies have shown that Amadori compounds are easily converted to HMF in dilute acid solution as well. Furthermore, Kato s (8) published preparation of 3-deoxyosone, in which glucose is reacted with N-butyl amine almost certainly involves the intermediate formation of an Amadori compound and its decomposition in situ. Thus, it can be reasonably concluded that 3-deoxyosones are produced from Amadori compounds during their degradation. 

Hodge et al. (45) discussed mechanisms for formation of methyl furanones and related substances from Amadori compounds. They have been produced by heating D-ribose and D-ribose phosphate with ammonia (46 47). Hicks and Feather (48) demonstrated that the Amadori compound 1-benzylamino-l-deoxy-D-threo-pentulose dehydrates to 4-hy-droxy-5-methyl-3(2H)-furanone and it has also been identified as a degradation product of L-ascorbic acid. This compound is believed to be formed from ribose-5-phosphate, and gained prominence when it was isolated from beef by Tonsbeck et al. (49). It became more apparent as a precursor of meat flavor when Van den Ouweland and Peer (50) reacted it and its thio analog with HaS to produce a number of sulfur compounds, some of which had meaty odors. 

Its formation from rhamnose heated with piperidine acetate in ethanol, under the same conditions that produced amino-hexose-reductones from glucose and other hexoses, was described as early as 1963 by Hodge et al., who confirmed the structure by IR and NMR data and proposed a formation pathway. The formation from Amadori intermediates was been reviewed by Vernin (1981). Numerous model systems have confirmed that it is one of the main Maillard-reaction products. For instance we will mention the formation from L-rhamnose and ethylamine (Kato et al., 1972) and from pentose/glycine or alanine, whose mechanism was proposed by Blank and Fay (1996) and Blank et al. (1998), from the intermediate Amadori compound, /V-(l-deoxy-D-pentos-l-yl)glycine. Furaneol is also formed by recombination of... 

Amadori compounds (N-substituted-l-amino-l-deoxy-2-ketoses) are potential precursors to the formation of many of these heterocyclic volatile products. The secondary nitrogen in most Amadori compounds is weakly basic and is therefore a likely site for rapid nitrosation reactions via normal reactions with nitrous acid, under mildly acidic conditions. However, purified Amadori compounds are usually obtained only after tedious isolation procedures are invoked to separate them from the complex mixtures of typical Maillard browning systems. Takeoka et al. ( 5) reported high performance liquid chromatographic (HPLC) procedures to separate Amadori compounds in highly purified form on a wide variety of columns, both of hydrophilic and hydrophobic nature. They were able to thus demonstrate that reaction products could be followed for kinetic measurements as well as to ensure purity of isolated products. 

It is well known that the Maillard reaction in foods is initiated by the formation of colorless and tasteless intermediates, which preferentially are formed in low-moisture systems ( ,5.). In this way by reaction of glucose with amino acids fructose-amino acids are formed via Amadori rearrangement of the primary glucosyl-ami-no acids (1 ). Fructose-amino acids e.g. have been isolated from freeze-dried apricots and peaches ( 6,7,8j. Amadori compounds arising from aldoses and amino acids are formed during drying of foods of plant origin and can be easily detected by amino acid analysis (j>). 

The furan isomaltol (7) and the pyran maltol ( 8 ) (Scheme 3) are consistent with having been formed via a 1-deoxyosone intermediate. Cyclization of such an intermediate and the loss of 2 additional moles of water allow one to arrive at these structures. Data which supports this is found in papers by Hodge and his group (1 3), who synthesized 1-deoxy-l-piperidino-maltulose (J5, Scheme 4) and showed that on further heating, it was converted to galactosyl isomaltol (JJJ). This is convincing evidence that isomaltol is sugar derived and is produced from an Amadori compound. Furthermore, the structure is wholly consistent with the formation of a 4-0-substituted 1-deoxyosone as an intermediate in the reaction. 

Since Amadori compounds are secondary amines, the question of the formation and reactivity of /V-nitroso derivatives arises. Accordingly, Pool el al 22 tested those derived from glucose with Ala, Asp, Phe, Gly, Ser, and Try in five strains of S. typhimurium with and without S9. The first three compounds were not mutagenic, the next two showed low but reproducible increases in the number of his+ revertants in TA1535 (without S9), but the last, containing indolyl-nitrosamine-D-fructose-L-tryptophan, was mutagenic in all five strains, with and without S9. When separated, the Try compound was mutagenic in three strains, without S9. 

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