Czech J. Food Sci., 2001, 19(1):13-18 | DOI: 10.17221/6568-CJFS

Novel Strecker degradation products of tyrosine and dihydroxyphenylalanine

J. Adamiec, K. Cejpek, J. R�ssner, J. Vel��ek

Institute of Chemical Technology - Department of Food Chemistry and Analysis, Prague, Czech Republic

Tyrosine was oxidised with either potassium peroxodisulphate or glyoxal. Volatile reaction products were isolated and analysed by GC/FID and GC/MS, derivatised with diazomethane and analysed by the same methods. Eight reaction products were identified. The major products were the expected Strecker aldehyde (4-hydroxyphenylacetaldehyde) and its lower homologue 4-hydroxybenzaldehyde. They were followed by 1-(4-hydroxyphenyl)-3-propionaldehyde, phenylacetaldehyde, benzaldehyde, phenol, 4-hydroxybenzoic, and benzoic acid. Analogously, the oxidation of 3,4-dihydroxyphenylalanine yielded the corresponding Strecker aldehyde (3,4-dihydroxyphenylacetaldehyde), its lower homologue 3,4-dihydroxybenzaldehyde, 3,4-dihydroxybenzoic, 3,4-dihydroxyphenylacetic, and caffeic acid. An identification of these oxidation products of tyrosine and 3,4-dihydroxyphenylalanine assumes homolytic cleavage of the Strecker aldehydes and a recombination of free radicals formed by this cleavage. As minor products, six O- and N-heterocyclic compounds arose in systems containing glyoxal (pyrazine, methyl- and ethylpyrazine, 3-furancarbaldehyde, 5-methyl-2-furancarbaldehyde, 2-pyrrolcarbaldehyde).

Keywords: Strecker degradation; amino acids; glyoxal; sodium peroxodisulphate; radicals; tyrosine; 3,4-dihydroxyphenyl-alanine (DOPA); 4-hydroxyphenylacetaldehyde, 3,4-dihydroxyphenylacetaldehyde

Published: February 28, 2001  Show citation