Naturally occurring secondary amino acids, with proline as the main representative, contain an alpha-imino group in a cycle that is typically four-, five-, and six-membered. The unique ring structure exhibits exceptional properties-conformational rigidity, chemical stability, and specific roles in protein structure and folding. Many proline analogues have been used as valuable compounds for the study of metabolism of both prokaryotic and eukaryotic cells and for the synthesis of compounds with desired biological, pharmaceutical, or industrial properties. The D-forms of secondary amino acids play different roles in living organisms than the L-forms. They have different metabolic pathways, biological, physiological, and pharmacological effects, they can be indicators of changes and also serve as biomarkers of diseases. In the scientific literature, the number of articles examining D-amino acids in biological samples is increasing. The review summarises information on the occurrence and importance of D- and L-secondary amino acids-azetidic acid, proline, hydroxyprolines, pipecolic, nipecotic, hydroxypipecolic acids and related peptides containing these D-AAs, as well as the main analytical methods (mostly chromatographic) used for their enantiomeric determination in different matrices (biological samples, plants, food, water, and soil).
- MeSH
- aminokyseliny * chemie MeSH
- iminokyseliny * chemie MeSH
- peptidy MeSH
- prolin chemie MeSH
- stereoizomerie MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
L-amino acids (L-AAs) play different important roles in the physiology of all living organisms. Their chiral counterparts, D-amino acids (D-AAs) are increasingly being recognized as essential molecules in many biological systems. Secondary amino acids with cyclic structures, such as prolines, exhibit conformational rigidity and thus unique properties in the structural and protein folding. Despite their widespread occurrence, much less attention was paid to their chiral analysis, particularly when the minor, typically D-enantiomer, is present in low amounts in a complex biological matrix. In this paper, a cost-effective, chiral GC-MS method is described for capillary Chirasil-L-Val separation of nine cyclic secondary amino acid enantiomers with four-, five-, and six-membered rings, involving azetidine-2-carboxylic acid, pipecolic acid, nipecotic acid, proline, isomeric cis/trans 3-hydroxy, 4-hydroxyproline, and cis/trans-5-hydroxy-L-pipecolic acid in the excess of its enantiomeric antipode. The sample preparation involves in-situ derivatization with heptafluorobutyl chloroformate, simultaneous liquid-liquid micro-extraction into isooctane followed by amidation of the arising low-polar derivatives with methylamine, an evaporation step, re-dissolution, and final GC-MS analysis. The developed method was used for analyses of human biofluids, biologically active peptides containing chiral proline constituents, and collagen.
- MeSH
- fluorokarbony chemie MeSH
- formiáty chemie MeSH
- iminokyseliny analýza chemie MeSH
- kalibrace MeSH
- lidé MeSH
- methylaminy chemie MeSH
- plynová chromatografie s hmotnostně spektrometrickou detekcí metody normy MeSH
- reprodukovatelnost výsledků MeSH
- stereoizomerie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
This review introduces β-fluorophosphonates as useful synthons and fluoroalkyl transfer reagents. The remarkable biological activity of the phosphonates is also mentioned. The main emphasis is put on synthetic applications of the following fluorinated phosphonates: diethyl (difluoromethyl)phosphonate (1), diethyl (trifluoromethyl)phosphonate (2), tetraethyl (fluoromethylene)bis¬phosphonate (3), diethyl [(fluoromethyl) (phenylsulfonyl)methyl]phosphonate (McCathy’s reagent) (4), and diethyl (fluoronitromethyl)phosphonate (5). The review is focused on the chemistry of the synthons.
- MeSH
- aktivní transport MeSH
- alkylace MeSH
- antivirové látky MeSH
- bisfosfonáty * chemie klasifikace MeSH
- chemie organická MeSH
- farmakologické účinky MeSH
- fluor chemie MeSH
- inhibitory enzymů MeSH
- lidé MeSH
- organofosfonáty * chemie klasifikace MeSH
- pojmy organické chemie MeSH
- vztahy mezi strukturou a aktivitou * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
A new route to α-alkyl-α-fluoromethylenebisphosphonates, 2 has been developed starting from commercially available tetraethyl fluoromethylenebisphosphonate (1), and alkyl halides using either caesium carbonate in DMF or sodium dimsyl. De-esterification of 2 provided biologically important α-alkyl-α-fluoromethylenebisphosphonic acid, 3, while alkoxide-induced carbon-phosphorus bond cleavage of 2 gave α-fluorophosphonates, 4, which are useful synthons in organic synthesis.
