Simultaneous determination of 18 D-amino acids in rat plasma by an ultrahigh-performance liquid chromatography-tandem mass spectrometry method: application to explore the potential relationship between Alzheimer's disease and D-amino acid level alterations.
D-Amino acids are increasingly being recognized as important signaling molecules, and abnormal levels of D-amino acids have been implicated in the pathogenesis of Alzheimer's disease. To evaluate the potential relationship between Alzheimer's disease and D-amino acids, a simple, sensitive, and reliable UPLC-MS/MS method with pre-column derivatization was developed and validated for simultaneous determination of 18 D-amino acids in rat plasma. The analytes were extracted from plasma samples by a protein precipitation procedure, and then derivatized with (S)-N-(4-nitrophenoxycarbonyl) phenylalanine methoxyethyl ester [(S)-NIFE]. Chromatographic separation was achieved using an ACQUITY UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm) with a mobile phase composed of acetonitrile containing 8 mM ammonium hydrogen carbonate at a flow rate of 0.6 mL min(-1). The analytes were detected by electrospray ionization in positive ion multiple reaction monitoring modes. Under the optimum experimental conditions, all the linear regressions were acquired with r > 0.9932. The limits of quantitation of all derivatized D-amino acids were within 0.05-40.0 ng mL(-1) in rat plasma. The intra- and inter-day precisions, expressed as percentage relative standard deviations (%RSD), were within the range of 12.3 and 10.1%, respectively. The recoveries for all the analytes were observed over the range of 82.8-100.5% with RSD values less than 12.5%. Finally, the proposed method was successfully applied to simultaneous determination of the 18 D-amino acids in plasma from Alzheimer's disease rats and age-matched normal controls. Results showed that the concentrations of D-serine, D-aspartate, D-alanine, D-leucine, and D-proline in Alzheimer's disease rat plasma were significantly decreased compared with those in normal controls, while D-phenylalanine levels increased. It was revealed that some of these D-amino acids would be potential diagnostic biomarkers for Alzheimer's disease.
School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road Shenhe District, Shenyang, Liaoning, 110016, China.
Yuping
Y
Xing
School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road Shenhe District, Shenyang, Liaoning, 110016, China.
Xiaoyan
X
Li
School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road Shenhe District, Shenyang, Liaoning, 110016, China. gxjhyz@aliyun.com.
Xingjie
X
Guo
School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road Shenhe District, Shenyang, Liaoning, 110016, China. cuiyan_13@126.com.
Yan
Y
Cui
D000544:Alzheimer Disease / Q000097:blood* / Q000378:metabolism; D000596:Amino Acids / Q000097:blood* / Q000737:chemistry; D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D053719:Tandem Mass Spectrometry / Q000379:methods*
D000596:Amino Acids
Alzheimer’s disease; Biomarkers; D-Amino acids; Pre-column derivatization; UPLC-MS/MS