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Current Perspectives and Methods for the Characterization of Natural Medicines
Published in Rohit Dutt, Anil K. Sharma, Raj K. Keservani, Vandana Garg, Promising Drug Molecules of Natural Origin, 2020
Muthusamy Ramesh, Arunachalam Muthuraman, Nallapilai Paramakrishnan, Balasubramanyam I. Vishwanathan
Chromatography is a major method for the separation of bioactive products from natural resources. This technique works based on the distribution of molecules in different phases. The natural compounds are distributed into two different phases, i.e. stationary phase and mobile phase. Based on the relative distribution of the chemical constituents, the constituents are separated. Chromatography is functioning by different methods: (i) column/adsorption chromatography; (ii) partition chromatography; (iii) paper chromatography; (iv) thin-layer chromatography; (v) gas-liquid chromatography; (vi) gas-solid chromatography; and (vii) ion-exchange chromatography. The parameters such as retention factor, selectivity, efficiency, retention time, and peak area are investigated for the structural characterization of marine products based on chromatography. Different types of chromatography techniques employed in the isolation and characterization of phytochemicals and marine constituents are tabulated in Table 2.1.
Thin-Layer Chromatographic Techniques and Systems
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
James A. Chan, Adorjan Aszalos
Partition chromatography utilizes the differences in solubility in two solvent systems of the different constituents of a mixture. In this case, members of the mixture are separated according to the influences on solubility exerted by their functional groups, by conformation of the molecules, and by solvation properties of the molecules. Substances used for the stationary phase are chiefly water, glycols, formamides, dimethylsulfoxide, and fatty acids or their derivatives alone or in combination with another. A variety of solvent or solvent mixtures can be used for the mobile phase. In partition TLC, the plates are covered with a solid support that carries the stationary phase. Silica gel, cellulose, or alumina is commonly used as the solid support. In partition TLC, the chamber is usually saturated with both phases. Theories of partition chromatography, which are based on either equilibrium or kinetic approaches, are adequately treated in the literature [11,12].
Planar Chromatography
Published in Joseph Chamberlain, The Analysis of Drugs in Biological Fluids, 2018
Using the ascending technique, the paper can be formed into a cylinder and placed with its lower 1 to 2 cm in the mobile phase a few centimeters away from the spotted sample. This method takes longer than the equivalent descending system, particularly if a heavy solvent such as dichloromethane is used in the mobile phase. Although this simple type of paper chromatography would appear to be absorption chromatography, there is usually sufficient water absorbed into the cellulose fibers to make the separation depend partly on an organic-aqueous partition. To make the chromatography more reproducible, and to make the system completely liquid-liquid partition, the paper is usually pre-equilibrated with the vapor of the stationary phase, which should be saturated with the mobile phase. The usual practice is to enclose the whole system in an airtight jar containing a mixture of the phases, and after a suitable period of equilibration, perform the elution with the mobile phase saturated with the stationary phase. For partition chromatography, temperature can be critical, and even in modern, temperature-controlled laboratories, local air currents can distort the flow of the mobile phase, making the chromatography irreproducible. Thus, most paper chromatography requires temperature control, usually by placing the solvent tank in an incubator. This not only allows reproducible chromatography, but the mass transfer between phases is also more rapid and chromatographic efficiency is improved.
Glycyrrhiza glabra-Enhanced Extract and Adriamycin Antiproliferative Effect on PC-3 Prostate Cancer Cells
Published in Nutrition and Cancer, 2020
Katerina Gioti, Anastasia Papachristodoulou, Dimitra Benaki, Apostolos Beloukas, Argyro Vontzalidou, Nektarios Aligiannis, Alexios-Leandros Skaltsounis, Emmanuel Mikros, Roxane Tenta
The roots of Glycyrrhiza glabra (Fabaceae family) were harvested in Kefalonia island (Greece). The plant material was dried by lyophilization, pulverized, and stored at ∼4 °C until it was processed. Twenty gram of the dried and pulverized plant material was extracted with ethanol (150 ml) (Merck, Darmstadt, Germany) at 70 °C by accelerated solvent extraction technique using an apparatus Dionex 300 (Thermo Fisher Scientific, USA). The removal of the solvent by distillation under vacuum (Rotavapor R-3000r, Buchi, Switzerland) resulted to the dry ethanolic extract (1.85 g, 9.25% yield). The extract was then submitted for fractionation using a biphasic solvents system Hex:EtOAc: MeOH:H2O 3:7:3:7 in a fast-centrifugal partition chromatography (FCPC) instrument (Kromaton, France). The fraction (0.35 g), which is enriched in the flavonoid glabridin (Fig. 1a) as TLC analysis revealed, was proceeded for its biological evaluation (GGE); 0.020 g of GGE was subjected to preparative TLC analysis (Merck Kieselgel 60 F254), which was performed with Hexane/EtOAc 30/70, afforded glabridin (0.011 g) in purity greater than 95% as revealed by the 1H-NMR spectrum (Bruker Advance III 600 MHz and DRX 400 MHz, Bruker GmbH, Germany) (Fig. 1b).
On the potential of micro-flow LC-MS/MS in proteomics
Published in Expert Review of Proteomics, 2022
Yangyang Bian, Chunli Gao, Bernhard Kuster
The overall performance of the entire analytical configuration largely depends on the quality and optimal interplay of the constituent components. At the beginning of the twentieth century, the foundations of chromatography were laid by Michail Semjonowitsch Tswett [3,4] when pigments were separated in columns packed with calcium carbonate. In 1952, the Nobel Prize was awarded to Martin and Synge for their seminal work on partition chromatography [5], and the first commercial LC systems emerged in the 1960s. Since then, LC systems have continued to develop in several directions; however, for proteomics, reversed phase (RP) stationary phases have dominated the field. This is because the acidified aqueous/organic solvent systems used in RPLC enable relatively straightforward online interfacing with mass spectrometry (MS). The beginning of MS also dates back about 100 years when Joseph John Thomson, Francis W. Aston, and Arthur J. Dempster constructed the first mass spectrometers [6]. Nevertheless, it was only in the late 1980s that soft ionization techniques were developed that subsequently enabled the transfer of large and polar molecules (i.e. peptides and proteins) into the gas phase without thermal decomposition. In 2002, John Fenn and Koichi Tanaka were awarded the Nobel Prize in chemistry for their fundamental work on electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI), respectively [7]. ESI was particularly successful for proteomic analyses because the molecules are ionized from the liquid phase, thus enabling the direct interfacing of ESI with a liquid chromatographic separation system.