Quantitation of Thioprolines in Grape Wine by Isotope Dilution–Liquid Chromatography–Tandem Mass Spectrometry

Abstract

Cysteine reacts with reactive carbonyls to form thioprolines, which have been demonstrated to possess various pharmaceutical properties. Therefore, thioproline formation is considered as a major detoxification pathway for carcinogenic reactive carbonyls. In this study, we report the initial identification of thiazolidine-4-carboxylic acid (1) and 2-methylthiazolidine-4-carboxylic acid (2), two very common thioprolines, formed by reacting formaldehyde and acetaldehyde with cysteine in grape wine samples. We have developed an isotope dilution-liquid chromatography-tandem mass spectrometry method featuring high sensitivity (limit of detection of ≤1.5 ng/mL) and selectivity to quantitate compounds 1 and 2. The method after validated to be highly accurate (recovery of ≥92%) and precise [intraday relative standard deviation (RSD) of ≤4.1% and interday RSD of ≤9.7%] was applied to determine the varying compound 1 and 2 contents in grape wine samples. Results revealed the grape type and storage duration-dependent formation of thioprolines in grape wines. Overall, the results are expected to facilitate compound-dependent investigations of the health benefits of grape wine, and our findings could be adopted to predict the age of grape wine.

Thioproline Serves as an Efficient Antioxidant Protecting Human Cells from Oxidative Stress and Improves Cell Viability

“…Isotope-labeled Lthioproline ([ 13 C, 2 H 2 ]-L-thioproline) was synthesized by reacting [ 13 C, 2 H 2 ]-formaldehyde with L-cysteine and was purified by reversephase HPLC, as described previously. 19 Using a similar approach, [ 13 C 3 ]-L-thioproline was also synthesized by reacting [ 13 C 3 ]-L-cysteine with formaldehyde. Isotope-labeled oxidized glutathione was synthesized by incubating glutathione-([ 13 C 2 , 15 N]glycine) in 0.5 M H 2 O 2 at 37 °C for 3 h and was purified by reverse-phase HPLC.…”

Automated In-Injector Derivatization Combined with High-Performance Liquid Chromatography–Fluorescence Detection for the Determination of Semicarbazide in Fish and Bread Samples

“…Compound 1 is non-fluorescent and demonstrated a poor chromatographic retention in RP-HPLC. Fmoc-Cl that has been extensively used as a fluorescent-tagging reagent in amino acid analysis was used to produce a nonpolar Fmoc moiety to enhance the chromatographic behavior of compound 1 in RP-HPLC. , HPLC–FLD analysis of compound 1 derivatized with Fmoc-Cl revealed efficient formation of a fluorescent product at a chromatographic retention time of 5.9 min (Figure ). Similar to the fluorometric properties of Fmoc-Cl, those of 1 -Fmoc showed fluorescence excitation and emission maxima at 260 and 320 nm, respectively.…”

“…Borate buffer, one of the most commonly used derivatization buffers, − was chosen as the reaction medium for the derivatization reaction. In contrast to other alkaline buffers, e.g., carbonate buffer, borate buffer produced a homogeneous solution for HPLC analysis.…”

“…Isotope-labeled semicarbazide ( 13 C, 15 enhance the chromatographic behavior of compound 1 in RP-HPLC. 31,32 HPLC−FLD analysis of compound 1 derivatized with Fmoc-Cl revealed efficient formation of a fluorescent product at a chromatographic retention time of 5.9 min (Figure 2). Similar to the fluorometric properties of Fmoc-Cl, those of 1-Fmoc showed fluorescence excitation and emission maxima at 260 and 320 nm, respectively.…”

Thioproline formation as a driver of formaldehyde toxicity inEscherichia coli

“…This hypothesis explains why deleting PepP does not increase sensitivity to acetaldehyde, glyoxal, or methylglyoxal (Supplementary Figure S1). Acetaldehyde reacts with free cysteine to form the thioproline analog 2-methylthioproline [37] but this amino acid is almost surely not charged to tRNA and incorporated into proteins [38], and acetaldehyde has not been reported to react with peptidyl-cysteine; hence there would be no 2-methylthioproline-containing peptides for PepP to cleave. Glyoxal and methylglyoxal cannot react with cysteine to form thiazolidine adducts (i.e.…”