Submitted to: Amino Acids
Publication Type: Review article
Publication Acceptance Date: 4/6/2011
Publication Date: 4/26/2011
Citation: Friedman, M., Levin, C.E. 2011. Nutritional and medicinal aspects of D-amino acids. Amino Acids. 10.100/s00726-011-0915-1. Interpretive Summary: A recent report in the journal Science showed that unnatural D-amino acids inhibited the formation and facilitated the destruction of bacterial biofilms. It is also possible that changing natural L-amino acid residues to D-isomers in bacterial toxins and allergy-causing proteins may reduce their toxic and allergic potential. These considerations and our published studies on the formation, analysis, and dietary significance of D-amino acids in processed foods induced us to accept an invitation from the Editor of the Journal of Chromatography to contribute a review paper on nutritional, microbiological, and medicinal aspects of D-amino acids to a special issue devoted to this subject. Our paper discusses the nutritional value of D-amino acids, D-peptides, and amino acid derivatives and offers brief summaries of on dietary, microbiological, pharmacological, and medicinal aspects of 24 individual D-amino acids and isomeric amino acid derivatives. The described results provide a valuable record and resource for further progress on the multi-faceted aspects of D-amino acids in food and biological samples.
Technical Abstract: This paper describes a method for determining the nutritional value of D-amino acids, D-peptides, and amino acid derivatives using a growth assay in mice fed a synthetic all-amino acid diet. A large number of experiments were carried out in which a molar equivalent of the test compound replaced a nutritionally essential amino acid such as L-lysine (L-Lys), L-methionine (L-Met), L-phenylalanine (L-Phe), and L-tryptophan (L-Trp) as well as the semi-essential amino acids L-cysteine (L-Cys) and L-tyrosine (L-Tyr). The results show wide-ranging variations in the biological utilization of test substances. The method is generally applicable to the determination of the biological utilization and safety of any amino acid derivative as a potential nutritional source of the corresponding L-amino acid. Because the organism is forced to use the D-amino acid or amino acid derivative as the sole source of the essential or semi-essential amino acid being replaced, and because a free amino acid diet allows better control of composition, the use of all-amino-acid for such determinations may be preferable to protein-based diets. Also covered are brief summaries of the widely-scattered literature on dietary, microbiological, pharmacological, and medicinal aspects of 24 individual D-amino acids and isomeric amino acid derivatives. The described results provide a valuable record and resource for further progress on the multi-faceted aspects of D-amino acids in food and food and biological samples.