title: Effect of amino acids on the formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in creatinine/phenylalanine and creatinine/phenylalanine/4-oxo-2-nonenal reaction mixtures.
abstract: 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation in mixtures of creatinine, phenylalanine, amino acids and 4-oxo-2-nonenal was studied, to analyse the role of amino acids on the generation of this heterocyclic aromatic amine. When oxidised lipid was absent, cysteine, serine, aspartic acid, threonine, asparagine, tryptophan, tyrosine, proline, and methionine increased significantly (p < 0.05) the amount of PhIP formed in comparison to the control. When lipid was present, only the addition of methionine, glycine, and serine increased significantly (p < 0.05) the amount of PhIP produced, while histidine, cysteine, lysine, tryptophan, tyrosine, and alanine reduced significantly (p < 0.05) PhIP. These results may be a consequence of the different competitive reactions that occur. Thus, in the absence of lipids, thermal decomposition of the amino acids produced reactive carbonyls that converted phenylalanine into phenylacetaldehyde as a key step in the formation of PhIP. When oxidised lipid was present, amino acids competed with phenylalanine for the lipid, and amino acid degradation products were formed, among which alpha-keto acids seemed to play a role in these reactions. These results suggest that PhIP can be produced by several alternative reaction pathways from all major food components, including amino acids and lipids, in addition to carbohydrates.
authors.affiliation: Instituto de la Grasa, Consejo Superior de Investigaciones Científicas, Avenida Padre García Tejero 4, 41012 Seville, Spain.
authors.forename: Rosario
authors.initials: R
authors.lastname: Zamora
authors.forename: Esmeralda
authors.initials: E
authors.lastname: Alcón
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Hidalgo
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D000596:Amino Acids / Q000737:chemistry*; D003404:Creatinine / Q000737:chemistry*; D006358:Hot Temperature; D007093:Imidazoles / Q000737:chemistry*; D010649:Phenylalanine / Q000737:chemistry*
chemical_list: C403894:4-oxo-2-nonenal; D000447:Aldehydes; D000596:Amino Acids; D007093:Imidazoles; D010649:Phenylalanine; C049584:2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine; D003404:Creatinine
keywords: 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine; 3-methyl-2-oxobutyric acid; 3-methyl-2-oxovaleric acid; 4-hydroxyphenylpyruvic acid; 4-methyl-2-oxovaleric acid; 4-oxo-2-nonenal; AlaKA; Amino acids; CRN; CysKA; GluKA; GlyKA; HAAs; Heterocyclic amines; IleKA; LeuKA; Lipid oxidation; MRM; Maillard reaction; MetKA; ON; PhIP; Phe; PheKA; Reactive carbonyls; TyrKA; ValKA; creatinine; glyoxylic acid; heterocyclic aromatic amines; mercaptopyruvic acid; multiple reaction monitoring; phenylalanine; phenylpyruvic acid; pyruvic acid; α-Keto acids; α-keto-γ-methylthiobutyric acid; α-ketoglutaric acid