Determination of d-serine in human serum by LC-MS/MS using a triazole-bonded column after pre-column derivatization with (S)-4-(3-isothiocyanatopyrrolidin-1-yl)-7- (N, N-dimethylaminosulfonyl)-2,1,3-benzoxadiazole

Abstract

An LC-MS/MS-based method for determining D-serine (Ser), an endogenous co-agonist of the N-methyl-D-aspartate receptor, in human serum, was developed and validated using a triazole-bonded silica-packed column after pre-column fluorescence derivatization with a chiral labeling reagent, (S)-4-(3-isothiocyanatopyrrolidin-1-yl)-7-(N,N-dimethylaminosulfonyl)-2,1,3-benzoxadiazole. Enantiomeric separation of the D- and L-Ser derivatives occurred in the triazole-bonded column (R s: 1.85) with CH3CN/100 mM HCO2NH4 in H2O (95.5:4.5) as the mobile phase with isocratic elution. The ln(capacity factor of D-Ser) in the van't Hoff plot gradually decreased with the inverse of temperature, suggesting enhanced hydrophilic interactions with the triazole-bonded stationary phase with increasing column temperature, owing to decrease in the partition coefficient to the mobile phase. Multiple reaction monitoring (m/z 457.10 > 409.00) by triple quadrupole mass spectrometry was used for quantifying D-Ser in human serum. The presence of D-Ser in the serum was confirmed by treatment with commercial D-amino acid oxidase. A linear calibration curve was constructed in the D-Ser concentration range of 0.5-5.0 μM (r (2) = 0.999, n = 3) using D-homoserine as the internal standard. The precision and recovery values were adequate for quantification. The detection limit for D-Ser was 1.1 fmol/injection (signal-to-noise ratio = 3), owing to the high CH3CN content in the mobile phase. The proposed LC-MS/MS method showed few fluctuations in the retention times of D- and L-Ser, and R s was stable until the 40th injection of serum without column washing, and thus can be useful for D-Ser determination in human serum in clinical research.

Determination of l‐tryptophan and l‐kynurenine derivatized with (R)‐4‐(3‐isothiocyanatopyrrolidin‐1‐yl)‐7‐(N,N‐dimethylaminosulfonyl)‐2,1,3‐benzoxadiazole by LC‐MS/MS on a triazole‐bonded column and their quantification in human serum

“…We recently reported a unique retention phenomenon, whereby the temperature of a triazole-bonded column considerably affected the retention behaviour of (S)-DBD-PyNCS-D, L-serine (Sakamoto et al, 2016). In the previous study, an increase in column temperature led to an increased capacity factor (k) of (S)-DBD-PyNCS-D,L-serine.…”

“…triazole-bonded silica packed column (Cosmosil HILIC®), after derivatization with (S)-DBD-PyNCS. Using the LC-MS/MS method, the enantiomeric separation and highly sensitive detection of both serine enantiomers in human serum were successfully achieved (Sakamoto et al, 2016).…”

Chromatographic profiles of tryptophan and kynurenine enantiomers derivatized with (S)‐4‐(3‐isothiocyanatopyrrolidin‐1‐yl)‐7‐(N,N‐dimethylaminosulfonyl)‐2,1,3‐benzoxadiazole using LC–MS/MS on a triazole‐bonded column

“…It has been reported that augmentation of the triazole‐bonded column temperature leads to an increased capacity factor ( k ) and ion intensity of ( R )‐DBD‐PyNCS‐ l ‐Trp and ‐ l ‐KYN . We also recently reported that the simultaneous determination of both endogenous d ‐ and l ‐serine in human serum was achieved by liquid chromatography (LC)‐MS/MS using a triazole‐bonded column after derivatization of the d ‐ and l ‐serine with ( S )‐DBD‐PyNCS . In this study, it was found that the d ‐enantiomer eluted earlier than the l ‐enantiomer of serine using ( S )‐DBD‐PyNCS on the triazole‐bonded column.…”

Evaluation of chiral separation efficiency of a novel OTPTHE derivatization reagent: Applications to liquid‐chromatographic determination of DL‐serine in human plasma

“…D‐Ser is abundant in the forebrain and function zone as a co‐agonist of NMDA receptors to enhance neurotransmission . Decreased D‐Ser levels in the plasma or serum have been reported in clinical studies of schizophrenia patients . Plasma concentrations of D‐serine and the ratio of D‐serine to total serine may be used as clinically translatable biomarkers in NMDA receptor‐related disease .…”

“…15,16 Decreased D-Ser levels in the plasma or serum have been reported in clinical studies of schizophrenia patients. 17,18 Plasma concentrations of D-serine and the ratio of D-serine to total serine may be used as clinically translatable biomarkers in NMDA receptorrelated disease. 19 D-amino acid has been gradually accepted as a new target molecule due to its physiological effect.…”