Highly sensitive novel fluorescent chiral probe possessing (S)-2-methylproline structures for the determination of chiral amino compounds by ultra-performance liquid chromatography with fluorescence: An application in the saliva of healthy volunteer

Simultaneous determination of free DL-amino acids in human hair with a novel DBD-M-Pro derivatization by UHPLC-HRMS: An application in diabetes patients

Human hair is a non-invasive biological sample that is easy to collect and store and can reflect long-term body health. However, the correlation between DL-amino acids and metabolic diseases in hair samples has not been studied. Therefore, we propose a novel UHPLC-HRMS method for analyzing seven free chiral amino acids (DL-Thr, DL-Glu, DL-Ala, DL-Val, DL-Pro, DL-Leu, and DL-Phe) simultaneously in hair samples by derivatization of chiral probe 4-(N,N-dmethylaminosulfonyl)-2,1,3-benzoxadiazole-trans-2-methyl-L-proline (DBD-M-Pro) labeled with targeted amino functional groups. Gradient elution was carried out using an ACQUITYTM BEH C18 (100×2.1 mm,1.7 μm) column with a mobile phase of 0.15 % formic acid (FA) in 10 mM ammonium acetate (CH3-COONH4) and 0.2 % FA in acetonitrile. The labelled DL-amino acid diastereoisomers could be completely separated, with a resolution (Rs) of 1.59-11.44. These amino acids show a strong linear correlation within the range of 3.1-99.2 pmol (R2 ≥ 0.9990). Intraday and interday precision was 1.87 %-14.87 %. The average recovery was 96.12 %-105.33 %. The limit of detection (LOD) ranged from 0.29 to 2.11 pmol. We then employed the method to determine the concentration of free chiral amino acids in hair samples from 30 healthy volunteers (HVs) and 30 diabetes patients (DPs). Male diabetes patients had significantly higher levels of L-Thr, L-Val, L-Leu (p < 0.05), and D-Ala (p < 0.01) in their hair samples than male healthy volunteers and female diabetes patients had significantly higher levels of D-Ala (p < 0.05) in their hair samples than female healthy volunteers. This is the first study to confirm the feasibility of using free DL-amino acids in human hair as potential biomarkers for diabetes.

Development and evaluation of a novel fluorescent chiral derivatization reagent DBD-S-M-Pro: first observation of four chiral amino acids in human hair

This study reports a novel fluorescent chiral derivatization reagent, 4-(N,N-dmethylaminosulfonyl)-2,1,3-benzoxadiazole-(2-succinimidoxy)-trans-2-methyl-L-proline (DBD-S-M-Pro), with a benzoxadiazole structure containing an N-hydroxysuccinimide activation group. DBD-S-M-Pro targets chiral amino-functional compounds under alkaline conditions without a condensation agent. Gradient elution was performed on a BEH C18 (100 × 2.1 mm, 1.7 μm) column with a mobile phase of 0.05% formic acid (FA) in 10 mM ammonium acetate (CH₃COONH₄) and 0.1% FA in acetonitrile or methanol. The efficiency of the chiral resolution was evaluated under excitation and emission wavelengths of 450 nm and 560 nm, respectively. The 19 chiral amino acids were separated in the range of 1.45-14.84. The resolutions of almost all DL-amino acids exceeded 1.5; the exceptions were serine (Ser) and lysine (Lys), with resolutions of 1.45 and 1.46, respectively. In addition, a new approach was devised for the simultaneous analysis of four chiral amino acids (DL-Glu, DL-Ala, DL-Val, and DL-Phe) in human hair. These amino acids were analyzed in the range of 12.5-400 pmol, with R² ≥ 0.9990, limits of detection (S/N = 3) of 4-10 pmol, and intraday and interday precisions of 0.57-6.23%. The average spikes in the hair recoveries were 89.76-111.54%, and the matrix effects were 92.47-102.40%. Next, the contents of free chiral amino acids in the hair samples of 10 healthy volunteers (five males and five females) were analyzed with this method, and the differences were compared. The developed DBD-S-M-Pro provides a novel strategy for the sensitive determination of free chiral amino acids in living organisms.

Development of a diphenyl sulfide structure derivatization reagent for amino acid enantiomers analysis: Application of dynamic monitoring in human urine after drinking wine

We developed a novel chiral mass spectrometry derivatization reagent (S)-(3-(4-carboxythiazolidin-3-yl)-3-oxopropyl) diphenylsulfonium (CTOD) with a positively charged sulfur-containing structure for high-sensitivity detection of the chiral resolution of amino acid enantiomers. CTOD reacted with DL-amino acids at 60^oC for 60 min to generate the corresponding diastereomers, fifteen chiral amino acid-derived products were separated. Resolution (Rs) values were of the range 1.54-4.36, except Asn 1.07, achieving good separation. A highly sensitive and selective UHPLC-MS/MS method for the simultaneous determination and chiral separation of five chiral amino acids (Pro, Ala, Glu, Asp, and Phe) based on CTOD derivatization was established and applied to the detection of chiral amino acids in different wines. The diastereomeric resolution of the five amino acids was 1.71-5.42, and an excellent linear relationship was obtained in the range of 0.25-500 pmol (R² ≥0.9993). The detection limit was 0.05-0.25 pmol. The intra- and inter-day precisions were 0.51-5.76% and 0.78-5.18%, respectively, and the average recovery was 90.03-99.99%. In addition, the metabolic concentration of chiral amino acids was monitored after drinking red wine and white wine, and the fitting curve of metabolic concentration was drawn.

Chirality in Organic and Mineral Systems: A Review of Reactivity and Alteration Processes Relevant to Prebiotic Chemistry and Life Detection Missions

Chirality is a central feature in the evolution of biological systems, but the reason for biology’s strong preference for specific chiralities of amino acids, sugars, and other molecules remains a controversial and unanswered question in origins of life research. Biological polymers tend toward homochiral systems, which favor the incorporation of a single enantiomer (molecules with a specific chiral configuration) over the other. There have been numerous investigations into the processes that preferentially enrich one enantiomer to understand the evolution of an early, racemic, prebiotic organic world. Chirality can also be a property of minerals; their interaction with chiral organics is important for assessing how post-depositional alteration processes could affect the stereochemical configuration of simple and complex organic molecules. In this paper, we review the properties of organic compounds and minerals as well as the physical, chemical, and geological processes that affect organic and mineral chirality during the preservation and detection of organic compounds. We provide perspectives and discussions on the reactions and analytical techniques that can be performed in the laboratory, and comment on the state of knowledge of flight-capable technologies in current and future planetary missions, with a focus on organics analysis and life detection.