In-depth mechanistic study on the formation of acrylamide and other vinylogous compounds by the Maillard reaction
In-depth mechanistic study on the formation of acrylamide and other vinylogous compounds by the Maillard reaction
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DOI：
10.1021/jf0495486
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发表时间：
2004-08-25
影响因子：
6.1
通讯作者：
Blank, I
中科院分区：
文献类型：
--
作者：
Stadler, RH;Robert, F;Blank, I
在基于天冬酰胺、还原糖、美拉德中间体和糖降解产物的低水分美拉德模型系统（180℃，5 分钟）中研究了丙烯酰胺的形成。我们的证据表明某些复合糖在丙烯酰胺的形成中发挥着重要作用。天冬酰胺的 N-糖基产生约 2.4 mmol/mol 丙烯酰胺，而用 α-二羰基和天冬酰胺的 Amadori 化合物产生 0.1-0.2 mmol/mol 丙烯酰胺。天冬酰胺的 Strecker 醇 3-羟基丙酰胺仅产生少量丙烯酰胺（大约 0.23 mmol/mol），而羟基丙酮将丙烯酰胺产率提高到 4 mmol/mol 以上，表明 α-羟基羰基在将天冬酰胺转化为丙烯酰胺方面比 α-二羰基更有效。实验结果与基于(i)席夫碱的Strecker型降解产生偶氮甲碱叶立德，随后(ii)脱羧的Amadori化合物的β-消除反应得到丙烯酰胺的反应机理一致。氮原子两侧的β位至关重要。偶氮甲碱叶立德重排为脱羧的阿马多里化合物是关键步骤，如果羰基部分在氮原子的β位上含有羟基，则这是有利的。通过在低湿度条件下反应合成获得的脱羧模型 Amadori 化合物，证明了氨基酸部分中的 β-消除步骤。仅当存在β-质子时才会产生相应的插烯化合物，例如，来自苯丙氨酸脱羧的阿马多里化合物的苯乙烯。因此，表明这种热途径可能是其他氨基酸所共有的，在某些条件下产生它们各自的插烯反应产物。
The formation of acrylamide was studied in low-moisture Maillard model systems (180degreesC, 5 min) based on asparagine, reducing sugars, Maillard intermediates, and sugar degradation products. We show evidence that certain glycoconjugates play a major role in acrylamide formation. The N-glycosyl of asparagine generated about 2.4 mmol/mol acrylamide, compared to 0.1-0.2 mmol/mol obtained with alpha-dicarbonyls and the Amadori compound of asparagine. 3-Hydroxypropanamide, the Strecker alcohol of asparagine, generated only low amounts of acrylamide (similar to0.23 mmol/mol), while hydroxyacetone increased the acrylamide yields to more than 4 mmol/mol, indicating that a-hydroxy carbonyls are much more efficient than a-dicarbonyls in converting asparagine into acrylamide. The experimental results are consistent with the reaction mechanism based on (i) a Strecker type degradation of the Schiff base leading to azomethine ylides, followed by (ii) a beta-elimination reaction of the decarboxylated Amadori compound to afford acrylamide. The beta-position on both sides of the nitrogen atom is crucial. Rearrangement of the azomethine ylide to the decarboxylated Amadori compound is the key step, which is favored if the carbonyl moiety contains a hydroxyl group in beta-position to the nitrogen atom. The beta-elimination step in the amino acid moiety was demonstrated by reacting under low moisture conditions decarboxylated model Amadori compounds obtained by synthesis. The corresponding vinylogous compounds were only generated if a beta-proton was available, for example, styrene from the decarboxylated Amadori compound of phenylalanine. Therefore, it is suggested that this thermal pathway may be common to other amino acids, resulting under certain conditions in their respective vinylogous reaction products.