Analysis of D-Amino Acids: Relevance in Human Disease

Abstract

Small metabolic molecules often are chiral and can play important roles in regulating a variety of biological functions, occasionally providing information about the presence and progression of disease. The most ubiquitous class of such small molecules are amino acids. Sensitive and accurate analysis of the less prevalent D-amino acids as free entities or as constituents of peptides can be challenging, particularly when complex physiological matrices are involved. The number of studies involving low-abundance D-amino acids in biological systems has increased significantly over the last decade. Studies involving their presence and importance have become increasingly difficult to ignore. Their relevance in neurological pathologies, cancer, kidney disorders, and more, has advanced. Chiral separations have played and continue to play a central role in these studies. Because enantiomers and epimers have the same exact mass, stereoselective separations are essential. However, sensitive detection is also necessary because trace levels of these analytes are involved. Multidimensional separations often provide the best avenue for accurate qualitative and quantitative results. Future developments will involve faster and highly specific routine testing, particularly if these analyses are to enter the clinical realm.