Effects of L-Cysteine and γ-Aminobutyric Acid Treatment on Postharvest Quality and Antioxidant Activity of Loquat Fruit during Storage.

Sichuan is the China's leading producer of loquat, with the largest cultivation area and yield ranked first in China. Loquat is a seasonal fruit highly appreciated by consumers; however, the fruit is prone to browning and lignification after harvest, affecting its storage quality. The effects of L-Cysteine (L-Cys, 0.01, 0.05, 0.1, 0.2%) and γ-aminobutyric acid (GABA, 0.025, 0.05, 0.075, 0.1%) on the sensory quality and antioxidant activity of loquat fruit during cold storage at 4 °C for 35 days and simulated shelf life for 5 days were investigated. The results showed that after 40 days of storage, compared with the control, 0.05% L-Cys and 0.05% GABA treatment of 'Zaozhong No. 6' loquat fruit effectively reduced the weight loss rate, browning index, decay index, respiratory rate, firmness, and lignin content and slowed the decreases in total soluble solids, soluble sugar, titratable acidityand vitamin C contents. The application of 0.05% L-Cys and 0.05% GABA significantly increased the contents of total phenols, total flavonoids, flavanols, and carotenoids; delayed the increase of relative electric conductivity, MDA, POD, and PPO activities; and significantly enhanced the activities of SOD and CAT, DPPH free radical scavenging ability, and FRAP, thereby improving antioxidant capacity. In summary, 0.05% L-Cys and 0.05% GABA treatment promotes the quality of loquat fruit after 40 days of storage, and significantly enhances antioxidant capacity, thus delaying senescence after harvest.

Simultaneous determination of 2-(3-hydroxy-5-phosphonooxymethyl-2-methyl-4-pyridyl)-1,3-thiazolidine-4-carboxylic acid and main plasma aminothiols by HPLC-UV based method.

The report presents the first method for simultaneous determination of plasma 2-(3-hydroxy-5-phosphonooxymethyl-2-methyl-4-pyridyl)-1,3-thiazolidine-4-carboxylic acid (HPPTCA), an adduct of cysteine (Cys) and active form of vitamin B6 pyridoxal 5'-phosphate (PLP), as well as total low molecular-weight thiols content, including Cys, homocysteine (Hcy), cysteinyl-glycine (Cys-Gly), and glutathione (GSH). The assay is based on high performance liquid chromatography coupled with ultraviolet detection (HPLC-UV) and involves disulfides reduction with tris(2-carboxyethyl)phosphine (TCEP), derivatization with 2-chloro-1-methylquinolinium tetrafluoroborate (CMQT) followed by sample deproteinization with perchloric acid (PCA). The chromatographic separation of obtained stable UV-absorbing derivatives is achieved on ZORBAX SB-C18 (150 × 4.6 mm, 5.0 µm) column using gradient elution with eluent consisted of 0.1 mol/L trichloroacetic acid (TCA), pH 1.7 and acetonitrile (ACN), delivered at a flow rate 1 mL/min. Under these conditions, the analytes are separated within 14 min at room temperature, and quantified by monitoring at 355 nm. Regarding HPPTCA, the assay linearity was demonstrated within a 1-100 µmol/L in plasma and the lowest concentration on the calibration curve was recognized as the limit of quantification (LOQ). The accuracy ranged from 92.74 to 105.57% and 95.43 to 115.73%, while precision varied from 2.48 to 6.99% and 0.84 to 6.98% for intra- and inter-day measurements, respectively. The utility of the assay was proved by application to plasma samples delivered by apparently healthy donors (n = 18) in which the HPPTCA concentration ranged from 19.2 to 65.6 µmol/L. The HPLC-UV assay provides complementary tool for routine clinical analysis, facilitating further studies on the role of aminothiols and HPPTCA in living systems.

Selenium Organic Content Prediction in Jengkol (Archidendron pauciflorum) and Its Molecular Interaction with Cardioprotection Receptors PPAR-γ, NF-κB, and PI3K.

Selenium (Se) is a trace mineral found in plants with a distinct sulfuric odor that is cardioprotective and reported to have low toxicity. West Java, Indonesia, has a variety of plants with a distinct odor that are consumed raw, such as jengkol (Archidendron pauciflorum). This study is conducted to determine the Se content of jengkol using the fluorometric method, where the jengkol extract is separated, and the Se content is detected using high-pressure liquid chromatography (HPLC), combined with fluorometry. Two fractions with the highest Se concentration (A and B) are found and characterized using liquid chromatography mass spectrometry to predict the organic Se content by comparing the results with those in the external literature. The Se content of fraction (A) is found to be selenomethionine (m/z 198), gamma glutamyl-methyl-selenocysteine-(GluMetSeCys; m/z 313), and the Se-sulfur (S) conjugate of cysteine-selenoglutathione (m/z 475). Furthermore, these compounds are docked on receptors involved in cardioprotection. The receptors are peroxisome proliferator-activated receptor-γ (PPAR-γ), nuclear factor kappa-B (NF-κB), and phosphoinositide 3-kinase (PI3K/AKT). The interaction of receptor and ligan that has the lowest binding energy of the docking simulation is measured with molecular dynamic simulation. MD is performed to observe bond stability and conformation based on root mean square deviation, root mean square fluctuation, radius gyration, and MM-PBSA parameters. The results of the MD simulation show that the stability of the complex organic Se compounds tested with the receptors is lower than that of the native ligand, while the binding energy is lower than that of the native ligand based on the MM-PSBA parameter. This indicates that the predicted organic Se in jengkol, i.e., gamma-GluMetSeCys to PPAR-γ, gamma-GluMetSeCys AKT/PI3K, and Se-S conjugate of cysteine-selenoglutathione to NF-κB, has the best interaction results and provides a cardioprotection effect, compared to the molecular interaction of the test ligands with the receptors.

Characterization of polysulfides in Saccharomyces cerevisiae cells and finished wine from a cysteine-supplemented model grape medium.

Polysulfide degradation in wine can result in hydrogen sulfide (H2S) release, imparting a rotten-egg smell that is detrimental to wine quality. Although the presence of wine polysulfides has been demonstrated, their biogenesis remains unclear. This study investigated the role of Saccharomyces cerevisiae in polysulfide formation during fermentation, with and without 5 mM cysteine supplementation as an H2S source. Using an established liquid chromatography-tandem mass spectrometry method, monobromobimane derivatives of hydropolysulfides, including CysSSSH, CysSSSSH and GSSSSH, and two oxidized polysulfides, GSSG and GSSSSG, were detected in yeast cells at the end of fermentation in a grape juice-like medium. Polysulfide production by four S. cerevisiae single deletion mutants (BY4743 Δcys3, Δcys4, Δmet17 and Δtum1) showed no significant differences compared to BY4743, suggesting that uncharacterized pathways maintain cellular polysulfide homeostasis. Five mM cysteine addition increased the formation of shorter sulfur chain species, including GSS-bimane and GSSG, but did not elevate levels of longer sulfur chain species. Additionally, polysulfides with even numbers of sulfur atoms tended to predominate in cellular lysates. Oxidized polysulfides and longer chain hydropolysulfides were not detected in finished wines. This evidence suggests that these polysulfides are unstable in wine-like environments or not transported extracellularly. Collectively, our data illustrate the complexity of yeast polysulfide metabolism under fermentation conditions.

Non-volatile cysteine sulphoxides and volatile organosulphur compounds in cloves of garlic (Allium sativum L.) and elephant garlic (Allium ampeloprasum L.) local accessions from northern and central Italy.

BACKGROUND: Garlic (Allium sativum L.) and other species of genus Allium are popular vegetables and food seasonings, owing to their spicy flavour and richness in health-promoting compounds. Several local garlic types are still grown on a small scale in different Italian regions, not being however yet properly characterized for their chemical composition. RESULTS: In the present investigation ten garlic and four elephant garlic (Allium ampeloprasum L.) populations cultivated in northern and central Italy were evaluated for their alk(en)yl cysteine sulphoxide (ACSO) and volatile compound profiles. Three non-volatile ACSOs (methiin, alliin, and isoalliin) and 27 volatile compounds were identified and quantified. A high and significant within-type variability was detected, with total ACSOs in the range 2759-5756, 4533-15 520, and 6565-10 643 mg kg-1 of fresh weight (f.w.). in elephant, white and red garlic, respectively. Elephant garlic showed a total sulphoxide content and a relative alliin amount significantly lower than white and red garlic. Remarkable within-type differences were also assessed for volatile compound content, ranging 260-599, 333-981, and 618-845 mg kg-1 f.w. in elephant, white, and red garlic, respectively. Diallyl trisulphide was the major individual compound, accounting for more than 0.30 mg mg-1 of volatiles in all the analysed samples. The three garlic types were clearly separated by discriminant analysis of analytical traits. CONCLUSION: This study investigated for the first time different Italian garlic and elephant garlic populations with respect to non-volatile and volatile organosulphur compound content, allowing the possibility of selecting garlic accessions according to the bioactive content. © 2022 Society of Chemical Industry.

Small in size, big on taste: Metabolomics analysis of flavor compounds from Philippine garlic.

Philippine garlic (Allium sativum L.) is arguably known to pack flavor and aroma in smaller bulbs compared to imported varieties saturating the local market. In this study, ethanolic extracts of Philippine garlic cultivars were profiled using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF). γ-Glu dipeptides, oligosaccharides and lipids were determined in Philippine garlic cultivars through bioinformatics analysis in GNPS Molecular Networking Platform and fragmentation analysis. Multivariate statistical analysis using XCMS Online showed the abundance of γ-Glu allyl cysteine in Batanes-sourced garlic while γ-Glu propenyl cysteine, γ-Glu methyl cysteine, and alliin are enriched in the Ilocos cultivar. Principal component analysis showed that the γ-Glu dipeptides found in local garlic influenced their distinct separation across PC1 from imported varieties. This presence of high levels of γ-Glu dipeptides and probiotic oligosaccharides may potentially contribute to the superior flavor and nutritional benefits of Philippine garlic.

Comparative phytochemical profile of the elephant garlic (Allium ampeloprasum var. holmense) and the common garlic (Allium sativum) from the Val di Chiana area (Tuscany, Italy) before and after in vitro gastrointestinal digestion.

This study is aimed to comparatively investigate the phytochemical profiles, focusing on the nutritional and phytochemical properties of common garlic (Allium sativum L.; CG) and elephant garlic (EG) (Allium ampeloprasum var. holmense) collected from the Val di Chiana area (Tuscany, Italy). The results showed a lower amount of fibers, demonstrating a higher digestibility of the bulb, and sulfur-containing compounds in EG rather than in CG. Untargeted metabolomic profiling followed by supervised and unsupervised statistics allowed understanding the differences in phytochemical composition among the two bulbs, both as raw bulbs, processed following the in vitro gastrointestinal digestion process. Typical sulfur-containing compounds, such as alliin and N-gamma-glutamyl-S-allyl cysteine, could notably be detected in lower amounts in EG. EG maintains a distinct phytochemical signature during in vitro gastrointestinal digestion. Our findings support the distinct sensorial attributes of the bulbs.

Furfuryl alcohol is a precursor for furfurylthiol in coffee.

This study investigated the role of furfuryl alcohol (FFA) in the formation of furfurylthiol (FFT), the most important odorant in roasted coffee, using in-bean and spiking experiments. Green beans were spiked with FFA, and after roasting FFT was quantified by stable isotope dilution analysis. The FFT level in the roasted beans increased dose-dependently with addition of FFA. Additionally, beans were spiked with isotopically labelled d2-FFA which generated isotopically labelled d2-FFT after roasting. However, no labelled furfural was observed. The results unambiguously show that FFA serves as a precursor of FFT in coffee. On the other hand, the data indicate that furfural stems not from oxidation of FFA and plays no major role as precursor for FFT formation during coffee roasting. The suggested formation pathway leads from FFA to the furfuryl cation, then protein-bound S-furfuryl-l-cysteine and by subsequent elimination to FFT.

Fabrication of a "Selenium Signature" Chemical Probe-Modified Paper Substrate for Simultaneous and Efficient Determination of Biothiols by Paper Spray Mass Spectrometry.

Significant efforts have been made to develop robust and reliable methods for simultaneous biothiols determination in different matrices, but there still exist the problems such as easy oxidation, tedious derivatization, and difficulty in discrimination, which brings unsatisfactory results in their accuracy and fast quantification in biological samples. To overcome these problems, a simultaneous biothiols detection method combining a "selenium signature" chemical probe and paper spray mass spectrometry (PS-MS) was proposed. In the strategy, the modified-paper substrate is used to enhance the analytical performance. Chemical probe Ebselen-NH2 that has a specific response to biothiols was designed and covalently fixed on the surface of an oxidized paper substrate. By the identification of derivatized product with distinctive selenium isotope distribution and employment of the optimized PS-MS method, qualitative and quantitative analysis of five biothiols including glutathione (GSH), cysteine (Cys), cysteinylglycine (CysGly), N-acetylcysteine (Nac), and homocysteine (Hcy) were realized. Biothiols in plasma and cell lysates were measured with satisfactory results. The established method not only provides a novel protocol for simultaneous determination of biothiols, but also is helpful for understanding the biological and clinical roles played by these bioactive small molecules.

High peroxidase-mimicking activity of gold@platinum bimetallic nanoparticle-supported molybdenum disulfide nanohybrids for the selective colorimetric analysis of cysteine.

Herein, gold@platinum (Au@Pt) bimetallic nanoparticles with high catalytic ability were in situ decorated onto a molybdenum disulfide (MoS2) surface to obtain nanocomposites (MoS2-Au@Pt) with high peroxidase-mimicking activity, which were used to construct a colorimetric sensor for cysteine (Cys) detection. Interestingly, this sensor can efficiently distinguish Cys from homocysteine (Hcy), glutathione (GSH) and 19 other amino acids with high sensitivity. As expected, the colorimetric sensor can determine the Cys content in Cys supplement tablets due to its high stability and repeatability. Finally, the detection mechanism was studied.

Black phosphorus quantum dots are useful oxidase mimics for colorimetric determination of biothiols.

Black phosphorus quantum dots (BP QDs) with small size are synthesized using an easy to operate thermal method. It was found that BP QDs possess oxidase-mimicking activity. They can catalyze the oxidation of the substrate 3,3',5,5'-tetramethylbenzidine to produce a blue-colored product even in the absence of hydrogen peroxide. Active oxygen species are proved to be involved in the reaction through the experiments of radical scavenging and electron spin resonance. Biothiols including reduced glutathione and cysteine inactivate the oxidase-mimicking activity of BP QDs, concomitant to the fading of the blue solution. This provides the  base for a colorimetric method for the determination of glutathione and cysteine. The decreased absorbance at 652 nm displays linear response to the concentrations of glutathione ranging from 0.1 to 5.0 µmol L-1, and cysteine from 0.1 to 10.0 µmol L-1. The detection limits are 0.02 µmol L-1 and 0.03 µmol L-1 for glutathione and cysteine, respectively. Successive determinations of 1.0 µmol L-1 glutathione and 5.0 µmol L-1 cysteine solution give relative standard deviations of 0.8% and 1.7% (n = 11), respectively. As a preliminary application, the practicability of the method was evaluated by the determination of glutathione in pharmaceutical preparations. This work not only discovers a useful oxidase mimics but also sets up a reliable platform based on BP QDs in colorimetric detection. Graphical abstract Schematic representation of colorimetric determination for biothiols through inactivating oxidase mimetic-like catalytic activity of black phosphorus quantum dots (BP QDs) on the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) with dissolved oxygen to produce its blue oxidized product (oxTMB).

Manganese oxide doped carbon dots for temperature-responsive biosensing and target bioimaging.

We report on the synthesis of manganese oxide doped CDs (MnOx-CDs) by a hydrothermal strategy using manganese (III) acetylacetonate (Mn(III) (C5H7O2)3) as the only raw materials. The MnOx-CDs exhibit water solubility, favorable biocompatibility, low cytotoxicity, and show blue fluorescence with excitation/emission maxima at 326/442 nm with a quantum yield of 11.3%, allowing efficient cellular imaging. The MnOx-CDs have a reversible temperature-sensitive fluorescent property in vitro within 10-60 °C, which can also be used as a sensitive thermometer in living cells. By a scratch assay, the MnOx-CDs can restrain the migration of HepG2 cancer cells, which make the MnOx-CDs be attractive candidates for liver cancer adjuvant treatment. Besides, the fluorescence of the MnOx-CDs is quenched in the presence of Fe3+ due to the formation of a nonfluorescent MnOx-CDs-Fe3+ complex between oxygen-containing groups on the surface of MnOx-CDs and Fe3+, and the quenched fluorescence of MnOx-CDs can be turn-on by dissociation of MnOx-CDs-Fe3+ complexes by biothiols including L-cysteine, homocysteine and glutathione. Therefore, the Fe3+ and biothiols can be sequentially detected with high reliability and accuracy via exploiting the on-off-on nanosensor at room temperature, respectively. Further application to detection biothiols in human serum indicated that the probe was practicality and feasibility in medical field.

Optimized one-pot derivatization and enantioseparation of cysteine: Application to the study of a dietary supplement.

Cysteine is a sulfur-containing amino acid which plays an outstanding role in many biological pathways in mammals. The analysis and quantification of native cysteine remains a critical issue due to its highly reactive thiol group evolving to the disulfide cystine derivative through oxidation reaction. Aimed at improving the derivative stability, cysteine was labelled with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), which reacts with both amino and thiol groups. The derivatization was optimized and the chemical identity of the reaction product was assessed via high-resolution mass spectrometry. The NBD-cysteine derivative resulted stable for 10 days. This derivative was enantioresolved (α and RS equal to 1.25 and 2.70, respectively) thanks to a (R,R)-Whelk-O1 phase with the following chromatographic setting: eluent, MeOH/water-90/10 (v/v) with 15 mM ammonium formate (pwsH 6.0); column temperature, 35 °C; flow rate, 1.0 mL/min. The developed method was validated following the ICH guidelines and applied for the quality control of a L-cysteine containing dietary supplement.

Evaluation of the Cadmium Accumulation in Tamarillo Cells (Solanum betaceum) by Indirect Electrochemical Detection of Cysteine-Rich Peptides.

Long-term cadmium intake can be very dangerous to human health due to its toxic effects. Although people can be contaminated with this element from different sources, contaminated food is probably the most important one. Foods such as vegetables and fruits can become contaminated with cadmium existing in soils, irrigation water, or chemical fertilizers. Some plants produce an excess of cysteine-rich peptides (CRp) when affected by high concentrations of heavy metals such as cadmium, thus indicating the presence of this type of contamination. Among these plants is tamarillo (Solanum betaceum), which is locally known as "tree tomato". This is a native plant widely consumed in the Ecuadorian Andes because of its abundance, low cost, and high content of vitamin C and fiber. The fact that Solanum betaceum produces CRp upon contamination with heavy metals means that this plant may be able to accumulate heavy metals. If this is the case, the plant can possibly be used as an indicator of metal pollution. The main goals of the present work were to evaluate the possibility of using Solanum betaceum as an indicator of metal contamination in plants and to examine its capability to accumulate metals. Both goals were met by determination of the amounts of CRp produced by Solanum betaceum cells cultivated in vitro in the laboratory under controlled conditions in the presence of different concentrations of cadmium. The CRp determination was carried out by means of electrogeneration of iodine in an iodide solution containing reduced glutathione as a biological thiol model. Solanum betaceum cells were grown in a Murashige and Skoog solution enriched with a 30 g L-1 sugar aqueous solution and 1 mg L-1 2,4-dichlorophenoxyacetic acid. The results of these experiments confirmed the following: (1) CRp production is a function of the amount of cadmium present as a contaminant up to a limiting value after which cell apoptosis occurs; (2) Solanum betaceum accumulates cadmium; (3) the analytical method used is appropriate for CRp determination; and (4) CRp determination is a valid alternative to detect contamination by heavy metals in plants.

A salting-out assisted liquid-liquid microextraction procedure for determination of cysteine followed by spectrophotometric detection.

A new analytical method for sensitive determination of cysteine based on its interaction with phenazine methosulfate was developed using salting-out liquid-liquid microextraction followed by spectrophotometric detection. The mechanism of the reaction was studied and confirmed by Fourier transform infrared and mass spectroscopy. Experimental parameters affecting the extraction efficiency were investigated and under the optimal conditions, good linearity was observed in the range 0.2 - 6.0 µg mL-1 with a correlation coefficient of 0.9972. The limit of detection and limit of quantification were found to be 0.07 and 0.21 µg mL -1, respectively. The enrichment factor was 25. The developed methodology was applied for analysis of cysteine in food supplements. The obtained data were in good agreement with LC-MS/MS analysis.

On-off-on fluorescent carbon dots from waste tea: Their properties, antioxidant and selective detection of CrO42-, Fe3+, ascorbic acid and L-cysteine in real samples.

In this work, we reported an economical plant-based hydrothermal method for one-pot green synthesis of water-soluble carbon dots (Tea-CDs) by using waste tea extract as a carbon source. The synthesized Tea-CDs were characterized by UV-visible, fluorescence, FT-IR, TEM, XPS and XRD. The Tea-CDs were found to remove hydroxyl and superoxide anion radical in vitro. In addition, the Tea-CDs exhibited bright blue fluorescence under UV-light (λex = 365 nm), and the fluorescence could be effectively quenched by CrO42- and Fe3+ ions. Meanwhile, the fluorescence of Tea-CDs-CrO42- and Tea-CDs-Fe3+ systems could be again easily recovered by ascorbic acid (AA) and L-cysteine (L-Cys). As an on-off-on fluorescent nano-sensor of the Tea-CDs, the sensitive detection of CrO42-, Fe3+, AA and L-Cys were all performed, showing that the good linear relationships between fluorescence intensity of Tea-CDs and concentration of all testing samples. Finally, the sensors successfully detected CrO42-, Fe3+, AA and L-Cys in commercially available real samples with satisfactory recovery ranges. The prepared sensors offer distinct advantages including low cost, simple handling, good sensitivity and high selectivity.

Fluorescent chemodosimeter for quantification of cystathionine-γ-synthase activity in plant extracts and imaging of endogenous biothiols.

A new reagent for quantification of CgS in plant extracts using a generalized methodology suitable for recognition of homocysteine (Hcy) with luminescence ON response.

Review: The promise and limits for enhancing sulfur-containing amino acid content of soybean seed.

Soybeans are an excellent source of protein in monogastric diets and rations with ∼75% of soybeans produced worldwide used primarily for animal feed. Even though soybeans are protein-rich and have a well-balanced amino acid profile, the nutritive quality of this important crop could be further improved by elevating the concentrations of certain amino acids. The levels of the sulfur-containing amino acids cysteine and methionine in soybean seed proteins are inadequate for optimal growth and development of monogastric animals, which necessitates dietary supplementation. Subsequently, concerted efforts have been made to increase the concentrations of cysteine and methionine in soybean seeds by both classical breeding and genetic engineering; however, these efforts have met with only limited success. In this review, we discuss the strengths and weakness of different approaches in elevating the sulfur amino acid content of soybeans. Manipulation of enzymes involved in the sulfur assimilatory pathway appears to be a viable avenue for improving sulfur amino acid content. This approach requires a through biochemical characterization of sulfur assimilatory enzymes in soybean seeds. We highlight recent studies targeting key sulfur assimilatory enzymes and the manipulation of sulfur metabolism in transgenic soybeans to improve the nutritive value of soybean proteins.

S-Allyl-L-cysteine sulfoxide, a garlic odor precursor, suppresses elevation in blood ethanol concentration by accelerating ethanol metabolism and preventing ethanol absorption from gut.

Alcoholic beverages are enjoyed together with meals worldwide, but their excessive intake is associated with an increased risk of various diseases. We investigated whether S-allyl-L-cysteine sulfoxide (ACSO), a sulfuric odor precursor of garlic, suppresses elevation in plasma ethanol concentration by accelerating ethanol metabolism and preventing ethanol absorption from the gut in rats. ACSO and garlic extract with a high ACSO content (Garlic-H) suppressed elevation in concentrations of ethanol and acetaldehyde in plasma and promoted the activities of alcohol dehydrogenase and aldehyde dehydrogenase. However, ACSO and Garlic-H did not affect plasma acetate so much. Furthermore, we examined the change in plasma ethanol concentration by injecting ACSO or Garlic-H into the ligated stomach or jejunum together with ethanol solution. ACSO and Garlic-H suppressed the absorption of ethanol from the stomach and jejunum, but suppression in the jejunum was less than in the stomach. In conclusion, ACSO inhibits ethanol absorption and accelerates ethanol metabolism.

Reductive amination derivatization for the quantification of garlic components by isotope dilution analysis.

In this work, we synthesized internal standards for four garlic organosulfur compounds (OSCs) by reductive amination with 13C, D2-formaldehyde, and developed an isotope dilution analysis method to quantitate these organosulfur components in garlic samples. Internal standards were synthesized for internal absolute quantification of S-allylcysteine (SAC), S-allylcysteine sulfoxide (alliin), S-methylcysteine (SMC), and S-ethylcysteine (SEC). We used a multiple reaction monitoring (MRM) to detect 13C, D2-formaldehyde-modified OSCs by ultrahigh-performance liquid phase chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) and obtained MS spectra showing different ratios of 13C, D2-formaldehyde-modified and H2-formaldehyde-modified compounds. The resulting labeled and unlabeled OSCs were exhibited correlation coefficient (R2) ranged from 0.9989 to 0.9994, respectively. The average recoveries for four OSCs at three concentration levels ranged from 89% to 105%. By 13C, D2-formaldehyde and sodium cyanoborohydride, the reductive amination-based method can be utilized to generate novel internal standard for isotope dilution and to extend the quantitative application.