RESUMEN
Glycomics, an emerging "omics" technology that was developed after genomics and proteomics, is a discipline that studies the composition, structure, and functions of glycomes in cells, tissues, and organisms. Glycomics plays key roles in understanding the laws of major life activities, disease prevention and treatment, and drug quality control and development. At present, the structural analysis of glycans relies mainly on mass spectrometry. However, glycans have low abundance in biological samples. In addition, factors such as variable monosaccharide compositions, differences in glycosidic bond positions and modes, diverse branching structures, contribute to the complexity of the compositions and structures of glycans, posing great challenges to glycomics research. Liquid chromatography can effectively remove matrix interferences and enhance glycan separation to improve the mass spectrometric response of glycans. Thus, liquid chromatography and liquid chromatography coupled with mass spectrometry are important technical tools that have been actively applied to solve these problems; these technologies play indispensable roles in glycomics research. Different studies have highlighted similarities and differences in the applications of various types of liquid chromatography, which also reflects the versatility and flexibility of this technology. In this review, we first discuss the enrichment methods for glycans and their applications in glycomics research from the perspective of chromatographic separation mechanisms. We then compare the advantages and disadvantages of these methods. Some glycan-enrichment modes include affinity, hydrophilic interactions, size exclusion, and porous graphitized carbon adsorption. A number of newly developed materials exhibit excellent glycan-enrichment ability. We enumerate the separation mechanisms of reversed-phase high performance liquid chromatography (RP-HPLC), high performance anion-exchange chromatography (HPAEC), hydrophilic interaction chromatography (HILIC), and porous graphitic carbon (PGC) chromatography in the separation and analysis of glycans, and describe the applications of these methods in the separation of glycans, glycoconjugates, and glyco-derivatives. Among these methods, HILIC and PGC chromatography are the most widely used, whereas HPAEC and RP-HPLC are less commonly used. The HILIC and RP-HPLC modes are often used for the separation of derived glycans. The ionization efficiency and detectability of glycans are significantly improved after derivatization. However, the derivatization process is relatively cumbersome, and byproducts inevitably affect the accuracy and completeness of the detection results. HPAEC and PGC chromatography exhibit good separation effects on nonderivative glycans, but issues related to the detection integrity of low-abundance glycans owing to their poor detection effect continue to persist. Therefore, the appropriate analytical method for a specific sample or target analyte or mutual verification must be selected. Finally, we highlight the research progress in various chromatographic methods coupled with mass spectrometry for glycomics analysis. Significant progress has been made in glycomics research in recent years owing to advancements in the development of chromatographic separation techniques. However, several significant challenges remain. As the development of novel separation materials and methods continues, chromatographic techniques may be expected to play a critical role in future glycomics research.
Asunto(s)
Glicómica , Polisacáridos , Glicómica/métodos , Polisacáridos/análisis , Polisacáridos/química , Cromatografía Liquida/métodos , Espectrometría de Masas/métodosRESUMEN
Supercritical fluid chromatography (SFC) is an environment-friendly and efficient column chromatography technology that was developed to expand the application range of high performance liquid chromatography (HPLC) using a supercritical fluid as the mobile phase. A supercritical fluid has a temperature and pressure that are above the critical values as well as relatively dynamic characteristics that are between those of a gas and liquid. Supercritical fluids combine the advantages of high solubility and diffusion, as their diffusion and viscosity coefficients are equivalent to those of a gas, while maintaining a density that is comparable with that of a liquid. Owing to the remarkable compressibility of supercritical fluids, analyte retention in SFC is significantly influenced by the density of the mobile phase. Thus, the column temperature and back pressure are crucial variables that regulate analyte retention in SFC. Increasing the back pressure can increase the density and solubility of the mobile phase, leading to reductions in retention time. The column temperature can affect selectivity and retention, and the degree to which different analytes are affected by this property varies. On the one hand, increasing the temperature reduces the density of the mobile phase, thereby extending the retention time of the analytes; on the other hand, it can also increase the energy of molecules, leading to a shorter retention time of the analyte on the stationary phase. CO2, the most widely employed supercritical fluid to date, presents moderate critical conditions and, more importantly, is miscible with a variety of polar organic solvents, including small quantities of water. In comparison with the mobile phases used in normal-phase liquid chromatography (NPLC) and reversed-phase liquid chromatography (RPLC), the mobile phase for SFC has a polarity that can be extended over a wide range on account of its extensive miscibility. The compatibility of the mobile phase determines the diversity of the stationary phase. Nearly all stationary phases for HPLC, including the nonpolar stationary phases commonly used for RPLC and the polar stationary phases commonly used for NPLC, can be applied to SFC. Because all stationary phases can use the same mobile-phase composition, chromatographic columns with completely different polarities can be employed in SFC. The selectivity of SFC has been effectively expanded, and the technique can be used for the separation of diverse analytes ranging from lipid compounds to polar compounds such as flavonoids, saponins, and peptides. The choice of stationary phase has a great impact on the separation effect of analytes in SFC. As new stationary phases for HPLC are constantly investigated, specialized stationary phases for SFC have also been continuously developed. Researchers have discovered that polar stationary phases containing nitrogen heterocycles such as 2-EP and PIC are highly suitable for SFC because they can effectively manage the peak shape of alkaline compounds and provide good selectivity in separating acidic and neutral compounds.The development of various stationary phases has promoted the applications of SFC in numerous fields such as pharmaceuticals, food production, environmental protection, and natural products. In particular, natural products have specific active skeletons, multiple active groups, and excellent biological activity; hence, these materials can provide many new opportunities for the discovery of novel drugs. According to reports, compounds related to natural products account for 80% of all commercial drugs. However, natural products are among the most challenging compounds to separate because of their complex composition and low concentration of active ingredients. Thus, superior chromatographic methods are required to enable the qualitative and quantitative analysis of natural products. Thanks to technological improvements and a good theoretical framework, the benefits of SFC are gradually becoming more apparent, and its use in separating natural products is expanding. Indeed, in the past 50 years, SFC has developed into a widely used and efficient separation technology. This article provides a brief overview of the characteristics, advantages, and development process of SFC; reviews the available SFC stationary phases and their applications in natural products over the last decade; and discusses prospects on the future development of SFC.
Asunto(s)
Cromatografía con Fluido Supercrítico , Cromatografía Líquida de Alta Presión , Cromatografía Liquida , Cromatografía con Fluido Supercrítico/métodos , Solventes/química , AguaRESUMEN
Eleven undescribed isoquinoline alkaloids corybungines A-K including a protoberberine-type alkaloid, an isoquinoline alkaloid with a unique 6-norprotoberberine skeleton, one 13,14-seco-protoberberine-type alkaloid, two 1a,14-seco-protoberberine-type alkaloids with a 4-(hydroxymethyl)phenoxy moiety and six aporphine alkaloids, together with seven known alkaloids, have been isolated from the whole herb extract of Corydalis bungeana Turcz. Their structures and absolute configurations were elucidated based on an analysis of spectroscopic data and electronic circular dichroism (ECD) spectra. (R)-stephanine displayed high antagonistic activity against the dopamine D2 receptor with an IC50 value of 0.85 ± 0.09 µM in CHO-D2 cells. Additionally, corybungines D, F, H, (R)-roemerine, (R)-vireakine and (R)-tuduranine showed moderate D2 antagonism (IC50 5.20-26.07 µM). The preliminary structure-activity relationships (SARs) of aporphine alkaloids were discussed.
Asunto(s)
Alcaloides , Aporfinas , Corydalis , Alcaloides/química , Alcaloides/farmacología , Aporfinas/farmacología , Dicroismo Circular , Corydalis/química , Isoquinolinas/química , Isoquinolinas/farmacología , Estructura Molecular , Receptores de Dopamina D2RESUMEN
Four new isoquinoline alkaloids including a benzophenanthridine alkaloid (1), a morphine derivative (2), a narceine-type alkaloid (3) and a simple isoquinoline alkaloid (4), a new amide alkaloid (5) and a new phthalic acid derivative (6), together with eleven known alkaloids (7-17) were obtained from the whole herbs extract of Corydalis bungeana Turcz. Their structures and absolute configurations were elucidated by extensive spectroscopic data analysis including HRESIMS, NMR and electronic circular dichroism (ECD) and ECD calculation. Compounds 1-17 were evaluated for dopamine D2 receptor activity in CHO-D2 cells. Among them, 16 showed the highest antagonistic activity on the D2 receptor with an IC50 value of 2.04 ± 0.01 µM. Compounds 14 and 15 exhibited moderate antagonism with IC50 values of 13.66 ± 2.28 and 31.72 ± 2.52 µM, respectively.
Asunto(s)
Alcaloides , Corydalis , Alcaloides/química , Alcaloides/farmacología , Amidas , Corydalis/química , Antagonistas de los Receptores de Dopamina D2 , Isoquinolinas/química , Isoquinolinas/farmacología , Estructura Molecular , Receptores de Dopamina D2RESUMEN
A dual retention combined with reversed-phase liquid chromatography (RP-LC) and hydrophilic interaction chromatography (HILIC) has been observed on beta-cyclodextrin (beta-CD) bonded stationary phase. A typical U-shaped retention curve was achieved owing to dual retention mechanism. Based on this observation, a beta-CD column can be operated under reversed-phase liquid chromatography (RP-LC) and hydrophilic interaction chromatography (HILIC) modes. Two-dimensional liquid chromatography (2D-LC) analysis can be realized on just a beta-CD column by switching these two different separation modes. In this study, off-line 2D-LC analysis for a natural product was carried out to prove the orthogonal separation between RP-LC and HILIC modes on a Click beta-CD column. Herba Hedyotis Diffusae, the whole grass of Hedyotis Diffusae wild was extracted with water, pretreated with macroporous resin and then first separated at RP-LC mode on the Click beta-CD column to obtain successive fractions, which were then reanalyzed at HILIC mode on the same Click beta-CD column. The result proved that both separation modes on the Click beta-CD column have good retention and peak shape, and these two separation modes have good orthogonality. 2D-LC analysis revealed abundant information in the natural product. Especially numerous minor components were enriched and separated. The mobile phase used in RP-LC and HILIC modes can be same and the switch between these two separation modes is easily realized by changing the ratio of the acetonitrile and water. Hence the mobile phase in this 2D-LC system is completely compatible. This advantage makes this combination is an appropriate 2D-LC method for the solutes having retention at both separation modes.