A Modified GC-MS Analytical Procedure for Separation and Detection of Multiple Classes of Carbohydrates

Resolution and quantification of carbohydrates by enantioselective comprehensive two-dimensional gas chromatography

Carbohydrates, in particular the d-enantiomers of ribose, 2-deoxyribose, and glucose, are essential to life's informational biopolymers (RNA/DNA) and for supplying energy to living cells through glycolysis. Considered to be potential biosignatures in the search of past or present life, our capacity to detect and quantify these essential sugars is crucial for future space missions to the Moon, Mars or Titan as well as for sample-return missions. However, the enantioselective analysis of carbohydrates is challenging and both research and routine applications, are lacking efficient methods that combine highly sensitive and reproducible detection with baseline enantioselective resolution and reliable enantiomeric excess (ee) measurements. Here, we present four different derivatization strategies in combination with multidimensional gas chromatography coupled to a reflectron time-of-flight mass spectrometer (GC×GC-TOF-MS) for the enantioselective resolution of C3 to C6 carbohydrates potentially suitable for sample-return analyses. Full mass spectral interpretation and calibration curves for one single-step (cyclic boronate derivatives) and three two-step derivatization protocols (aldononitrile-acetate, hemiacetalization-trifluoroacetylation, and hemiacetalization-permethylation) are presented for concentrations ranging from 1 to 50 pmol μL⁻1 with correlation coefficients R2 > 0.94. We compared several analytical parameters including reproducibility, sensitivity (LOD and LOQ), overall separation, chiral resolution (RS), mass spectrum selectivity, stability during long term storage, and reliability of ee measurements to guide the application-dependent selection of optimal separation and quantification performance.

Development of a joint derivatization protocol for the unequivocal identification of the monosaccharide composition in four dendrobium polysaccharides and free monosaccharide by GC-MS

The determination of monosaccharides is crucial for studying the structure of polysaccharides and the composition of free monosaccharides in living organisms. Based on previous derivatization gas chromatography-mass spectrometry (GC-MS) methods, we aimed to develop a novel analytical protocol for better quantifying monosaccharides. In this study, sugar alcohol acetylation, saccharonitrile acetylation, silylation and a combination of sugar alcohols acetylation and saccharonitrile acetylation were compared. The optimal method was verified with the monosaccharide determination of four polysaccharides and four free monosaccharides from Dendrobium. The results showed that the novel combined derivatization method was superior to the other three methods in terms of content analysis of monosaccharides. Furthermore, it possessed good linearity (all calibration curves showed relative coefficients ≥ 0.999), sensitivity, precision (relative standard deviation < 2%), and accuracy (recovery, 95.7-105%). Finally, the novel method established in this study was successfully employed in determining the monosaccharide composition of four polysaccharides and four free monosaccharide samples from Dendrobium.

Mass Spectrometric Identification of Metabolites after Magnetic-Pulse Treatment of Infected Pyrus communis L. Microplants

The major goal of this study is to create a venue for further work on the effect of pulsed magnetic fields on plant metabolism. It deals with metabolite synthesis in the aforementioned conditions in microplants of Pyrus communis L. So far, there have been glimpses into the governing factors of plant biochemistry in vivo, and low-frequency pulsed magnestatic fields have been shown to induce additional electric currents in plant tissues, thus perturbing the value of cell membrane potential and causing the biosynthesis of new metabolites. In this study, sixty-seven metabolites synthesized in microplants within 3-72 h after treatment were identified and annotated. In total, thirty-one metabolites were produced. Magnetic-pulse treatment caused an 8.75-fold increase in the concentration of chlorogenic acid (RT = 8.33 ± 0.0197 min) in tissues and the perturbation of phenolic composition. Aucubin, which has antiviral and antistress biological activity, was identified as well. This study sheds light on the effect of magnetic fields on the biochemistry of low-molecular-weight metabolites of pear plants in vitro, thus providing in-depth metabolite analysis under optimized synthetic conditions. This study utilized high-resolution gas chromatography-mass spectrometry, metabolomics methods, stochastic dynamics mass spectrometry, quantum chemistry, and chemometrics, respectively. Stochastic dynamics uses the relationships between measurands and molecular structures of silylated carbohydrates, showing virtually identical mass spectra and comparable chemometrics parameters.

Comprehensive applications of metabolomics on tea science and technology: Opportunities, hurdles, and perspectives

With the development of metabolomics analytical techniques, relevant studies have increased in recent decades. The procedures of metabolomics analysis mainly include sample preparation, data acquisition and pre-processing, multivariate statistical analysis, as well as maker compounds' identification. In the present review, we summarized the published articles of tea metabolomics regarding different analytical tools, such as mass spectrometry, nuclear magnetic resonance, ultraviolet-visible spectrometry, and Fourier transform infrared spectrometry. The metabolite variation of fresh tea leaves with different treatments, such as biotic/abiotic stress, horticultural measures, and nutritional supplies was reviewed. Furthermore, the changes of chemical composition of processed tea samples under different processing technologies were also profiled. Since the identification of critical or marker metabolites is a complicated task, we also discussed the procedure of metabolite identification to clarify the importance of omics data analysis. The present review provides a workflow diagram for tea metabolomics research and also the perspectives of related studies in the future.

Statistical optimization and characterization of fucose-rich polysaccharides extracted from pumpkin (Cucurbita maxima) along with antioxidant and antiviral activities

Biologically active phytochemicals from pumpkin reveal versatile medical applications, though little is known about their antiviral activity. The fucose-rich polysaccharide extraction conditions were optimized through Box-Behnken design and purified by column chromatography. The purified fucose-rich polysaccharide was characterized through SEM, FT-IR, ¹H NMR, XRD, TGA, and GS-MS. The analysis results revealed an irregular and porous surface of the purified polysaccharide with high fucose, rhamnose, galactose, and glucose contents. The tested fucose-rich polysaccharides revealed significant antioxidant and anti-inflammatory activity at very low concentrations. The purified fucose-rich polysaccharides exerted a broad-spectrum antiviral activity against both DNA and RNA viruses, accompanied by high safety toward normal cells, where the maximum safe doses (EC₁₀₀) were estimated to be about 3-3.9 mg/mL for both Vero and PBMC cell lines. Treatment of HCV, ADV7, HSV1, and HIV viruses with the purified polysaccharides showed a potent dose-dependent inhibitory activity with IC₅₀ values of 95.475, 20.96, 5.213, and 461.75 μg/mL, respectively. This activity was hypothesized to be through inhibiting the viral entry in HCV infection and inhibiting the reverse transcriptase activity in HIV. The current study firstly reported the antioxidant, anti-inflammatory, and antiviral activities of Cucurbita maxima fucose-rich polysaccharide against several viral infections.

Synthesis of naphthalimide-type chemsensor and its application in quality evaluation for polygonatum sibiricum Red

The premise and key of ensuring the safety and effectiveness of traditional Chinese medicine (TCM) is to construct appropriate quality evaluation system of TCM. This study aimed to establish a pre-column derivatization HPLC method for achieving the quality control of Polygonatum sibiricum by reacting synthesized 4-hydrazino-1,8-naphthalimide (HAN) with diverse monosaccharides from the hydrolytic product of P. sibiricum polysaccharides (PSPs), followed by HPLC separation. The HAN was synthesized based on a CuI-catalyzed cross-coupling reaction in water, and then employed as a novel chemosensor that reacts with reducing sugars. Good separation was achieved at a detection wavelength of 448 nm using an ZORBAX SB-C8 column under a gradient elution at a flow rate of 0.5 ml/min within 12 min. The monosaccharide compositions of PSP mainly include two hexoses [glucose (Glc), galactose (Gal)] and two hexuronic acids [glucuronic acid (GlcA) and galacturonic acid (GalA)], and the molar ratio of Glc, Gal, GlcA and GalA is 16.67:52.94:10.58:19.81. The verified HPLC method, possessing excellent precision and good accuracy, successfully achieved rapid qualitative and quantitative determination for PSP. Additionally, the HAN displayed fluorescence enhancement through “push–pull” mode, and fluorescence decreased through “pull–pull” mode after binding to monosaccharides, which is a potential for fluorescence determination of different monosaccharides.

Malva parviflora Leaves and Fruits Mucilage as Natural Sources of Anti-Inflammatory, Antitussive and Gastro-Protective Agents: A Comparative Study Using Rat Models and Gas Chromatography

Malva parviflora L., Little mallow, has been traditionally used as an alternative food source. It acts as a medicinal herb containing a potential source of mucilage thus herein; we aimed to assess the toxicity, anti-inflammatory, antitussive and gastro-protective actions of M. parviflora mucilage extracted from its leaves (MLM) and fruit (MFM). Toxicity studies were investigated by in vitro hemolytic assay whereas acute anti-inflammatory and antitussive activities were assessed by carrageenan-induced paw edema and sulphur dioxide induced cough model in rats, respectively. Gastro-protective effects were studied using ethanol induced acute and chronic gastric ulcer rat models. Their metabolic profiles were determined using gas chromatography. The results revealed that MLM and MFM were non-toxic towards human erythrocytes and their lethal doses were found to be greater than 5 g/kg. Pretreatment with MLM (500 mg/kg) and MFM (500 mg/kg) significantly reduced the carrageenan-induced paw thickness (p < 0.001). Maximum edema inhibition (%) was observed at 4 h in diclofenac sodium (39.31%) followed by MLM (27.35%) and MFM (15.68%). Animals pretreated with MLM (500 mg/kg) significantly lower the cough frequency in SO2 gas induced cough models in contrast to control. Moreover, MLM at doses of 250 and 500 mg/kg reduced the ethanol induced gastric mucosal injuries in acute gastric ulcer models presenting ulcer inhibition of 23.04 and 38.74%, respectively. The chronic gastric ulcer model MFM (500 mg/kg) demonstrated a remarkable gastro-protective effect showing 63.52% ulcer inhibition and results were closely related to standard drug sucralfate. In both models, MLM and MFM decreased gastric juice volume and total acidity in addition to an increased gastric juice pH and gastric mucous content justifying an anti-secretary role of this mucilage that was further confirmed by histopathological examination. Meanwhile, GC analyses of the mucilage revealed their richness with natural as well as acidic monosaccharides. It is concluded that MLM and MFM can be used therapeutically for the management of inflammation, cough and gastric ulcer.

Quantification of carbohydrates in human serum using gas chromatography–mass spectrometry with the stable isotope-labeled internal standard method

Comparison of two derivatization approaches (silylation and acylation) for carbohydrate separation based on optimizing reaction conditions by artificial neural networks.

Malva parviflora Leaves Mucilage: An Eco-Friendly and Sustainable Biopolymer with Antioxidant Properties

Malva parviflora L. is an edible and medicinal herb containing mucilaginous cells in its leaves. Mucilage obtained from M. parviflora leaves (MLM) was extracted in distilled water (1:10 w/v) at 70 °C followed by precipitation with alcohol. Preliminary phytochemical tests were performed to assess the purity of the extracted mucilage. Results showed that the yield of mucilage was 7.50%, and it was free from starch, alkaloids, glycosides, saponins, steroids, lipids and heavy metals. MLM had 16.19% carbohydrates, 13.55% proteins and 4.76% amino acids, which indicate its high nutritional value. Physicochemical investigations showed that MLM is neutral and water-soluble, having 5.84% moisture content, 15.60% ash content, 12.33 swelling index, 2.57 g/g water-holding capacity and 2.03 g/g oil-binding capacity. The functional properties, including emulsion capacity, emulsion stability, foaming capacity and stability increased with increased concentrations. Micromeritic properties, such as bulk density, tapped density, Carr’s index, Hausner ratio, and angle of repose, were found to be 0.69 g/cm³, 0.84 g/cm³, 17.86%, 1.22 and 28.5, respectively. Scanning electron microscopy (SEM) showed that MLM is an amorphous powder possessing particles of varying size and shape; meanwhile, rheological studies revealed the pseudoplastic behavior of MLM. The thermal transition process of MLM revealed by a differential scanning calorimetry (DSC) thermogram, occurring at a reasonable enthalpy change (∆H), reflects its good thermal stability. The presence of functional groups characteristic of polysaccharides was ascertained by the infrared (IR) and gas chromatography/mass spectrometry (GC/MS) analyses. GC revealed the presence of five neutral monosaccharides; namely, galactose, rhamnose, arabinose, glucose and mannose, showing 51.09, 10.24, 8.90, 1.80 and 0.90 mg/g of MLM, respectively. Meanwhile, galacturonic acid is the only detected acidic monosaccharide, forming 15.06 mg/g of MLM. It showed noticeable antioxidant activity against the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical with an IC₅₀ value of 154.27 µg/mL. It also prevented oxidative damage to DNA caused by the Fenton reagent, as visualized in gel documentation system. The sun protection factor was found to be 10.93 ± 0.15 at 400 µg/mL. Thus, MLM can be used in food, cosmetic and pharmaceutical industry and as a therapeutic agent due to its unique properties.

Non-derivatization strategy for the comprehensive characterization of neutral monosaccharide isomers and neutral disaccharide isomers using hydrophilic interaction liquid chromatography coupled to quadrupole/time-of-flight mass spectrometry

Monosaccharide isomers and disaccharide isomers widely exist in nature, playing a key role in a number of important biological processes. However, due to high structural similarity and high polarity, the characterization of monosaccharide isomers, disaccharide isomers, as well as the analysis of monosaccharide composition of polysaccharides by a method that does not require derivatization is an ongoing challenge. Herein, we proposed a simple method for rapid discrimination of non-derivatized neutral monosaccharide, and disaccharide isomers using hydrophilic interaction liquid chromatography coupled to quadrupole/time-of-flight mass spectrometry (HILIC-Q/TOF-MS). In this work, we optimized the experimental parameters, and detailed approaches to discriminate the precursor ions, deprotonated ions, and fragment ions are proposed, as well. To discriminate the various ions, the retention times, the relative abundance (RA) of precursor ions and fragment ions at different collision energies, the relative abundance ratio (RAR) of fragment ions to deprotonated ions or precursor ions were considered for characterization of neutral monosaccharide and disaccharide isomers. Finally, this strategy was successfully applied to analyzing the monosaccharide composition of neutral disaccharides, polysaccharides, and an aqueous extract of Moringa oleifera seeds. The experimental results revealed that the HILIC-Q/TOF-MS is an effective and convenient strategy for rapid differentiation of monosaccharide isomers and disaccharide isomers, which may serve as a general platform for the analysis of neutral polysaccharides, food, medicinal plants, and herbs.

Potential of the Red Alga Dixoniella grisea for the Production of Additives for Lubricants

There is an increasing interest in algae-based raw materials for medical, cosmetic or nutraceutical applications. Additionally, the high diversity of physicochemical properties of the different algal metabolites proposes these substances from microalgae as possible additives in the chemical industry. Among the wide range of natural products from red microalgae, research has mainly focused on extracellular polymers for additive use, while this study also considers the cellular components. The aim of the present study is to analytically characterize the extra- and intracellular molecular composition from the red microalga Dixoniella grisea and to evaluate its potential for being used in the tribological industry. D. grisea samples, fractionated into extracellular polymers (EPS), cells and medium, were examined for their molecular composition. This alga produces a highly viscous polymer, mainly composed of polysaccharides and proteins, being secreted into the culture medium. The EPS and biomass significantly differed in their molecular composition, indicating that they might be used for different bio-additive products. We also show that polysaccharides and proteins were the major chemical compounds in EPS, whereas the content of lipids depended on the separation protocol and the resulting product. Still, they did not represent a major group and were thus classified as a potential valuable side-product. Lyophilized algal fractions obtained from D. grisea were found to be not toxic when EPS were not included. Upon implementation of EPS as a commercial product, further assessment on the environmental toxicity to enchytraeids and other soil organisms is required. Our results provide a possible direction for developing a process to gain an environmentally friendly bio-additive for application in the tribological industry based on a biorefinery approach.

A New, Quick, and Simple Protocol to Evaluate Microalgae Polysaccharide Composition

In this work, a new methodological approach, relying on the high specificity of enzymes in a complex mixture, was developed to estimate the composition of bioactive polysaccharides produced by microalgae, directly in algal cultures. The objective was to set up a protocol to target oligomers commonly known to be associated with exopolysaccharides' (EPS) nutraceutical and pharmaceutical activities (i.e., rhamnose, fucose, acidic sugars, etc.) without the constraints classically associated with chromatographic methods, while maintaining a resolution sufficiently high to enable their monitoring in the culture system. Determination of the monosaccharide content required the application of acid hydrolysis (2 M trifluoroacetic acid) followed by NaOH (2 M) neutralization. Quantification was then carried out directly on the fresh hydrolysate using enzyme kits corresponding to the main monosaccharides in a pre-determined composition of the polysaccharides under analysis. Initial results showed that the enzymes were not sensitive to the presence of TFA and NaOH, so the methodology could be carried out on fresh hydrolysate. The limits of quantification of the method were estimated as being in the order of the log of nanograms of monosaccharides per well, thus positioning it among the chromatographic methods in terms of analytical performance. A comparative analysis of the results obtained by the enzymatic method with a reference method (high-performance anion-exchange chromatography) confirmed good recovery rates, thus validating the closeness of the protocol. Finally, analyses of raw culture media were carried out and compared to the results obtained in miliQ water; no differences were observed. The new approach is a quick, functional analysis method allowing routine monitoring of the quality of bioactive polysaccharides in algal cultures grown in photobioreactors.

Characterization of chemical components in the Guanxinning injection by liquid chromatography-mass spectrometry

Guanxinning injection (GXNI) is widely used in the treatments of cerebral thrombosis, cerebral hemorrhage, sequela, coronary disease, stenocardia, arrhythmia, and so on. For the herbal injections, more components should be characterized and quantified as much as possible to guarantee the drug safety. However, large numbers of the chemical constituents in the GXNI still remain unknown. In this study, ultrahigh performance liquid chromatography-Q Exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry (UHPLC-Q Orbitrap HRMS), in combination of nuclear magnetic resonance (NMR), was used to identify the components in GXNI, which led to the identification of 194 compounds. With the aid of solvent partition, more phthalides, diterpenoid quinines, and salvianolic acids were tentatively identified, and minor compounds with the other structural types were also detected. The structural diversity of phthalides and diterpenoid quinones were revealed by the structural network, and six phthalides and 13 diterpenoid quinones were further detected in GXNI with the help of the characteristic fragmentation pattern and structural network. In addition, NMR also revealed the presence of a series of primary metabolites in the GXNI, which could be used as a complimentary approach for the rapid identification of the chemical components in the traditional Chinese medicines (TCM). However, the unknown NMR signals of GXNI needed to be further identified to guarantee the drug safety.

Mass spectrometry in clinical glycomics: The path from biomarker identification to clinical implementation

Over the past decades, the genome and proteome have been widely explored for biomarker discovery and personalized medicine. However, there is still a large need for improved diagnostics and stratification strategies for a wide range of diseases. Post-translational modification of proteins by glycosylation affects protein structure and function, and glycosylation has been implicated in many prevalent human diseases. Numerous proteins for which the plasma levels are nowadays evaluated in clinical practice are glycoproteins. While the glycosylation of these proteins often changes with disease, their glycosylation status is largely ignored in the clinical setting. Hence, the implementation of glycomic markers in the clinic is still in its infancy. This is for a large part caused by the high complexity of protein glycosylation itself and of the analytical techniques required for their robust quantification. Mass spectrometry-based workflows are particularly suitable for the quantification of glycans and glycoproteins, but still require advances for their transformation from a biomedical research setting to a clinical laboratory. In this review, we describe why and how glycomics is expected to find its role in clinical tests and the status of current mass spectrometry-based methods for clinical glycomics.

Rapid Analysis of Monosaccharides in Sub-milligram Plant Samples Using Liquid Chromatography-Mass Spectrometry Assisted by Post-column Derivatization

Monosaccharides play important roles in plant growth and development, and their biofunctions are closely related to their endogenous contents. Therefore, the determination of monosaccharides is beneficial for the further study of monosaccharide biofunction. In this work, we developed a liquid chromatography-mass spectrometry analytical method assisted by a post-column derivatization technique (LC-PCD-MS) for the fast and automatic determination of 16 monosaccharides in samples. Post-column chemical derivatization of monosaccharides was performed by a reaction of monosaccharides with 4-benzylaminobenzeneboronic acid (4-PAMBA) through boronate ester formation in a three-way connector. 4-PAMBA worked as a derivatization reagent to improve the selectivity and sensitivity of monosaccharide detection by MS. The developed LC-PCD-MS method integrates LC separation, chemical derivatization, and MS detection in one run, thus greatly reducing the analysis time for each sample. The limits of detection and limits of quantification for 16 monosaccharides were in the range of 0.002-0.1 and 0.007-0.5 ng/mL, respectively. Good linearity was obtained from the linear regression, with a determination coefficient (R²) ranging from 0.9928 to 1.0000. The relative recoveries were in the range of 80.7-117.8%, with the intra- and interday relative standard deviations less than 19.7 and 16.5%, respectively, indicating good accuracy and acceptable reproducibility of the method. Finally, the method was successfully applied to investigate the spatial and temporal distribution of 16 monosaccharides in the developing flower and germinating seed of Arabidopsis thaliana.