Effect of Field Trial on Silymarin Complex Composition and Antioxidant Assessment of Milk Thistle (Silybum marianum L. Gaertner).

Plant foods are receiving increasing attention as a valuable source of health beneficial compounds. Understanding the impact of growing conditions on the quality of milk thistle is critical for determining appropriate agro-ecological and agro-economic parameters for its production and, subsequently, food products rich in health-beneficial compounds. For this purpose, a randomized milk thistle cultivation trial was established in the experimental field of Agritec Plant Research Plc. in Sumperk, Czech Republic, and carried out for two subsequent growing seasons in 2020 and 2021. The milk thistle achenes, variety Mirel, were sown in the row width of 12.5, 25 and 37 cm; and the qualitative parameters of each field trial such as achenes yields, silymarin complex determination and also antioxidant assessment (total phenolic content, total flavonoids content, DPPH and ABTS radical scavenging activity) were evaluated. The environmental impact of the extraction process was reduced by using pressurized liquid extraction with 60% EtOH (v/v). The weather conditions during the trial as well as the row spacing of milk thistle sowing were revealed to have a significant influence on the evaluated parameters (p ≤ 0.05). The highest yields of evaluated parameters were obtained for the growing season 2021 and the row spacing of 37 cm.

Fabrication of monolithic capillary columns with inner diameter 50-530 µm employing a mixture of pentaerythritol tetraacrylate and polyhedral oligomeric silsesquioxane-methacrylate as crosslinkers.

Highly crosslinked monolithic capillary columns with inner diameters in the range of 50-530 µm were prepared by radical polymerization of pentaerythritol tetraacrylate, polyhedral oligomeric silsesquioxane-methacrylate, and n-octadecyl methacrylate in the presence of methanol, dodecyl alcohol, and polyethylene glycol lauryl ether. Columns were evaluated by inverse size-exclusion chromatography employing a set of polystyrene standards of narrow molecular-size distribution and by scanning electron microscopy. Chromatographic performance under reversed-phase conditions was also evaluated. The combination of two effective crosslinkers as pentaerythritol tetraacrylate and polyhedral oligomeric silsesquioxane-methacrylate in the polymerization mixture allows for the preparation of robust and efficient monolithic capillary columns within a fairly wide range of internal diameters.

Identification of Aspergillus Conidia in Bronchoalveolar Lavage Using Offline Combination of Capillary Electrophoresis in Supercritical Water-Treated Fused Silica Capillary and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry.

Diagnosis of fungal infection in lung parenchyma is relatively difficult. Bronchoscopy with bronchoalveolar lavage is very useful in its diagnosing. Therefore, a method for rapid online concentration and analysis of Aspergillus conidia in bronchoalveolar lavage fluid using the combination of transient isotachophoresis (tITP) and micellar electrokinetic chromatography (MEKC) with subsequent off-line identification of the separated conidia by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is described in this study. In the proposed procedure, conidia were first dynamically adhered onto the roughened part of the inner surface of a fused silica capillary prepared by etching with supercritical water. Then the adhered conidia were desorbed, concentrated, and separated using a combination of tITP and MEKC. Finally, the fractions containing the separated conidia were collected from the capillary and analyzed by MALDI-TOF MS. The adhesion efficiency under the optimized experimental conditions was about 80%. This rapid diagnosis will contribute to timely initiation of therapy and increase the patient's chances of survival.

Nano-etched fused-silica capillary used for on-line preconcentration and electrophoretic separation of bacteriophages from large blood sample volumes with off-line MALDI-TOF mass spectrometry identification.

The properties of staphylococcal phages from the Siphoviridae, Podoviridae, and Myoviridae families were monitored using capillary electrophoretic methods on fused-silica capillaries with different morphology of surface roughness. Isoelectric points of the examined phages were determined by capillary isoelectric focusing in the original, smooth fused-silica capillary, and they ranged from 3.30 to 3.85. For capillary electrophoresis of phages, fused-silica capillaries with the "pock" and "cone" roughened surface types were prepared by etching a part of the capillary with supercritical water. The best resolution of the individual phages (to range from 3.2 to 4.6) was achieved with the "cone" surface-type fused-silica capillary. Direct application of phage K1/420 at the infection site, represented by human plasma or full blood spiked with Staphylococcus aureus, was on-line monitored by micellar electrokinetic chromatography. The phage particles were dynamically adhered onto the roughened surface of the capillary from 10 µL of the prepared sample at the optimized flow rate of 6.5 µL min-1. The limit of detection was determined to be 104 phage particles. The linearity of the calibration lines was characterized by the regression coefficient, R2 = 0.998. The relative standard deviation (RSD) of the peak area, calculated from ten independent measurements, was (±) 2%. After analysis, viability of the detected phages was verified by the modified "double-layer drop assay" method, and collected phage fractions were simultaneously off-line analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Graphical abstract.

Cohesive Energy Densities Versus Internal Pressures of Near and Supercritical Fluids.

Over half a century ago, Wiehe and Bagley suggested that a product of the internal pressure and molar volume of a liquid measures the energy of nonspecific intermolecular interactions whereas the cohesive energy reflects the total energy of intermolecular interactions in the liquid. This conjecture, however, has never been considered in connection with near and supercritical fluids. In this contribution, the cohesive energy density, internal pressure and their ratios are calculated from high precision equations of state for eight important fluids including water. To secure conformity to the principle of corresponding states when comparing different fluids, the calculations are carried out along the line defined by equality between the reduced temperature and the reduced pressure of the fluid (Tr = Pr). The results provide additional illustration of the tunability of the solvent properties of water that stands apart from those of other near and supercritical fluids in common use. In addition, an overview is also presented of the derivatives of cohesive energy density, solubility parameter and internal pressure with respect to temperature, pressure and molar volume.

Pre-concentration and separation of bacteria by volume coupling electrophoresis on supercritical water-etched fused silica capillary with two segments of different internal diameters and inner surface roughnesses.

The transient isotachophoretic stacking and sweeping was used for the on-line large-volume sample pre-concentration of bacteria, Escherichia coli and Staphylococcus aureus cells (methicillin-susceptible or methicillin-resistant), in the initial stage of micellar electrokinetic chromatography using a non-ionogenic surfactant or of capillary electrophoresis, respectively. These procedures were employed in single-piece fused silica capillary etched with supercritical water with two different internal diameter segments featuring different inner surface roughness. Large volumes (maximum 2.8 µL) of the high conductivity sample matrices, physiological saline solution, urine or blood (with purification step), spiked with examined cells were injected into the wider end of a capillary with an inlet inner diameter 195 µm. This novel on-line combination of preconcentration strategies for cells produced an up to 680-fold increase in sensitivity for E. coli or S. aureus cells. The average calculated resolutions, R, for five selected methicillin-susceptible or methicillin-resistant strains were found to be 6.3 for the agar-cultivated and 14.9 for the blood-incubated cells. A low number of bacteria similar to those in clinical samples were also tested. The modified surface roughness step helped to significantly narrow the cell zones and to increase resolution. The migration velocities of E. coli agar-cultivated and blood-incubated cells were approximately the same as those of S. aureus, probably due to the minimal differences in their surface properties. This procedure, on-line pre-concentration and separation of bacteria, is rapid and provides good reproducibility and repeatability.

Fused silica capillaries with two segments of different internal diameters and inner surface roughnesses prepared by etching with supercritical water and used for volume coupling electrophoresis.

In this work, single-piece fused silica capillaries with two different internal diameter segments featuring different inner surface roughness were prepared by new etching technology with supercritical water and used for volume coupling electrophoresis. The concept of separation and online pre-concentration of analytes in high conductivity matrix is based on the online large-volume sample pre-concentration by the combination of transient isotachophoretic stacking and sweeping of charged proteins in micellar electrokinetic chromatography using non-ionogenic surfactant. The modified surface roughness step helped to the significant narrowing of the zones of examined analytes. The sweeping and separating steps were accomplished simultaneously by the use of phosphate buffer (pH 7) containing ethanol, non-ionogenic surfactant Brij 35, and polyethylene glycol (PEG 10000) after sample injection. Sample solution of a large volume (maximum 3.7 µL) dissolved in physiological saline solution was injected into the wider end of capillary with inlet inner diameter from 150, 185 or 218 µm. The calibration plots were linear (R2 ∼ 0.9993) over a 0.060-1 µg/mL range for the proteins used, albumin and cytochrome c. The peak area RSDs from at least 20 independent measuremens were below 3.2%. This online pre-concentration technique produced a more than 196-fold increase in sensitivity, and it can be applied for detection of, e.g. the presence of albumin in urine (0.060 µg/mL).

Partition Coefficients of Organics between Water and Carbon Dioxide Revisited: Correlation with Solute Molecular Descriptors and Solvent Cohesive Properties.

High-pressure phase behavior of systems containing water, carbon dioxide and organics has been important in several environment- and energy-related fields including carbon capture and storage, CO2 sequestration and CO2-assisted enhanced oil recovery. Here, partition coefficients (K-factors) of organic solutes between water and supercritical carbon dioxide have been correlated with extended linear solvation energy relationships (LSERs). In addition to the Abraham molecular descriptors of the solutes, the explanatory variables also include the logarithm of solute vapor pressure, the solubility parameters of carbon dioxide and water, and the internal pressure of water. This is the first attempt to include also the properties of water as explanatory variables in LSER correlations of K-factor data in CO2-water-organic systems. Increasing values of the solute hydrogen bond acidity, the solute hydrogen bond basicity, the solute dipolarity/polarizability, the internal pressure of water and the solubility parameter of water all tend to reduce the K-factor, that is, to favor the solute partitioning to the water-rich phase. On the contrary, increasing values of the solute characteristic volume, the solute vapor pressure and the solubility parameter of CO2 tend to raise the K-factor, that is, to favor the solute partitioning to the CO2-rich phase.

Capillary electrophoresis in a fused-silica capillary with surface roughness gradient.

The electro-osmotic flow, a significant factor in capillary electrophoretic separations, is very sensitive to small changes in structure and surface roughness of the inner surface of fused silica capillary. Besides a number of negative effects, the electro-osmotic flow can also have a positive effect on the separation. An example could be fused silica capillaries with homogenous surface roughness along their entire separation length as produced by etching with supercritical water. Different strains of methicillin-resistant and methicillin-susceptible Staphylococcus aureus were separated on that type of capillaries. In the present study, fused-silica capillaries with a gradient of surface roughness were prepared and their basic behavior was studied in capillary zone electrophoresis with UV-visible detection. First the influence of the electro-osmotic flow on the peak shape of a marker of electro-osmotic flow, thiourea, has been discussed. An antifungal agent, hydrophobic amphotericin B, and a protein marker, albumin, have been used as model analytes. A significant narrowing of the detected zones of the examined analytes was achieved in supercritical-water-treated capillaries as compared to the electrophoretic separation in smooth capillaries. Minimum detectable amounts of 5 ng/mL amphotericin B and 5 µg/mL albumin were reached with this method.

Molecular Insight into Long-Wavelength Fluorogenic Dye Design: Hydrogen Bond Induces Activation of a Dormant Acceptor.

The detection of chemical or biological analytes in response to molecular changes relies increasingly on fluorescence methods. Therefore, there is a substantial need for the development of improved fluorogenic dyes. In this study, we demonstrated how an intramolecular hydrogen bond activates a dormant acceptor through a charge induction between phenolic hydrogen and a heteroaryl nitrogen moiety. As a result, a new fluorochrome is produced, and the molecule exhibits a strong fluorescent emission. When the strength of the hydrogen bonding was increased by conformational locking, the obtained dye emitted at longer wavelengths and fluoresced under physiological conditions. The dye was implemented in a turn-ON system responsive to hydrogen peroxide. The molecular insight provided by this study should assist in the design of fluorescent dyes that are suitable for in vitro and in vivo applications.

Separation of methicillin-resistant from methicillin-susceptible Staphylococcus aureus by electrophoretic methods in fused silica capillaries etched with supercritical water.

Identification and prevention of Staphylococcus aureus-caused infections may benefit from a fast and dependable method to distinguish between the methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) S. aureus strains. The current methods involving polymerase chain reaction and/or other molecular tests are usually laborious and time-consuming. We describe here a fast and low-cost method employing capillary zone electrophoresis (CZE) to distinguish between MRSA and MSSA. The method makes use of a supercritical water-treated fused silica capillary, the inner surface of which has subsequently been modified with (3-glycidyloxypropyl)trimethoxysilane. With optimized proportions of suitable additives to the background electrolyte, a CZE separation of MRSA from MSSA may be completed within 12 min. The cells were baseline-resolved, and resolution was determined to be 3.61. The isoelectric points of MSSA and MRSA were found to be the same for both groups of these strains, pI = 3.4.

Comprehensive study of ultrafast excited-state proton transfer in water and D2O providing the missing RO(-)···H(+) ion-pair fingerprint.

Steady-state and time-resolved optical techniques were employed to study the photoprotolytic mechanism of a general photoacid. Previously, a general scheme was suggested that includes an intermediate product that, up until now, had not been clearly observed experimentally. For our study, we used quinone cyanine 7 (QCy7) and QCy9, the strongest photoacids synthesized so far, to look for the missing intermediate product of an excited-state proton transfer to the solvent. Low-temperature steady-state emission spectra of both QCy7 and QCy9 clearly show an emission band at T < 165 K in H2O ice that could be assigned to ion-pair RO(-)*···H3O(+), the missing intermediate. Room-temperature femtosecond pump-probe spectroscopy transient spectra at short times (t < 4 ps) also shows the existence of transient absorption and emission bands that we assigned to the RO(-)*···H3O(+) ion pair. The intermediate dissociates on a time scale of 1 ps and about 1.5 ps in H2O and D2O samples, respectively.

Forming Homogeneous Three-Dimensional Structures from Discrete Silica Microspheres Using Sub/Supercritical Water.

A novel technique for producing highly uniform structures from silica microspheres has been developed and tested. It is based on exploiting the temperature- and pressure-dependent solvent properties of sub/supercritical water toward silicon dioxide. The initial concept aimed to create a "hybrid" capillary chromatographic column on the border between a packed and a monolithic column that would combine the benefits of both. The resultant method that integrates dissolution and coalescence in a continuous process enabled the production of a range of permeable columns with high efficiency and varying sizes. Their internal structures were examined using scanning electron microscopy and characterized using microHPLC chromatography. The structures produced using this method may have diverse applications beyond the scope of analytical chemistry. They prove useful in scenarios where high pressure is necessary because of the high hydraulic resistance of small particles and/or the passing medium with a high flow rate. A simple test of a bridged-microsphere monolithic column and a discrete microsphere-packed column, both after chemical modification to the C18 stationary phase, indicated superior performance of the new type of monolithic columns.

Monte Carlo-Simulated Annealing and Machine Learning-Based Funneled Approach for Finding the Global Minimum Structure of Molecular Clusters.

Understanding the physical underpinnings and geometry of molecular clusters is of great importance in many fields, ranging from studying the beginning of the universe to the formation of atmospheric particles. To this end, several approaches have been suggested, yet identifying the most stable cluster geometry (i.e., global potential energy minimum) remains a challenge, especially for highly symmetric clusters. Here, we suggest a new funneled Monte Carlo-based simulated annealing (SA) approach, which includes two key steps: generation of symmetrical clusters and classification of the clusters according to their geometry using machine learning (MCSA-ML). We demonstrate the merits of the MCSA-ML method in comparison to other approaches on several Lennard-Jones (LJ) clusters and four molecular clusters-Ser8(Cl-)2, H+(H2O)6, Ag+(CO2)8, and Bet4Cl-. For the latter of these clusters, the correct structure is unknown, and hence, we compare the experimental and simulated fragmentation patterns, and the fragmentation of the proposed global minimum matches experiments closely. Additionally, based on the fragmentation of the predicted betaine cluster, we were able to identify hitherto unknown neutral fragmentation channels. In comparison to results obtained with other methods, we demonstrated a superior ability of MCSA-ML to predict clusters with high symmetry and similar abilities to predict clusters with asymmetrical structures.

Near- and supercritical water as a diameter manipulation and surface roughening agent in fused silica capillaries.

The prospects of near- and supercritical water for treatment of the inner surfaces of fused silica capillaries have been tested employing an in-lab-assembled apparatus. Unlike all other agents used for the purpose, water cannot introduce any undesirable heteroatoms to the treated surface. Theoretical background for this work comes from the well-known fact that water near its critical point can solubilize silica. The results show that depending on the temperature, water flow rate, flow mode, and exposure time, high-temperature water has wide-ranging effects on both the surface roughness and the internal diameter profile along the length of the treated capillary. By judicious selection of the operating conditions, tapered capillaries of various profiles for applications in electromigration techniques can be prepared with relatively high reproducibility. The water-treated fused silica capillaries with uniform internal diameter appear to be useful for preparation of monolithic silica capillary columns.

Isoelectric focusing in continuously tapered fused silica capillary prepared by etching with supercritical water.

This communication indicates the potential of etching with sub- and/or supercritical water for reproducible preparation of fused-silica capillaries with tapered geometry suitable for capillary isoelectric focusing (CIEF) with electroosmotic displacement. The etching procedure provided a single-piece combination of the tapered separation space with a cylindrical connection of the detection window to the electrode vial. Selected proteins and colored pI markers were used as model analytes. A comparison with conventional cylindrical capillary under comparable applied voltage and analysis time was made, and the resultant peaks were compared in terms of peak resolution under optimized conditions. In CIEF carried out in a tapered capillary with the inlet cross-section three times larger than the cross-section at the detection window, three to four times higher resolutions of corresponding peak pairs were obtained. The method described opens the way to increase the number of separable compounds without resorting to excessively high voltage.

Combination of capillary isoelectric focusing in a tapered capillary with MALDI-TOF MS for rapid and reliable identification of Dickeya species from plant samples.

This study was undertaken to investigate feasibility of a combination of capillary isoelectric focusing (CIEF) in a tapered fused silica (FS) capillary with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for a rapid and reliable identification of bacteria taken from plant-tissue-containing samples. Eight strains representing different species of the genus Dickeya were selected on the basis of close proximity of their isoelectric points: D. chrysanthemi, D. chrysanthemi bv. parthenii, D. chrysanthemi bv. chrysanthemi, D. dadantii, D. paradisiaca, D. solani, D. diffenbachiae, and D. dianthicola. Because the Dickeya species (spp.) cannot be easily discriminated from each other when CIEF is performed in a cylindrical FS capillary (commonly used in CIEF) even if a narrow pH gradient is used, a tapered FS capillary was employed instead, which enabled satisfactory discrimination of the examined bacteria due to enhanced separation efficiency of CIEF in the tapered FS capillary. CIEF in the tapered FS capillary was also successfully used for the detection and characterization of Dickeya spp. in a plant-tissue-containing sample. Then an off-line combination of CIEF with MALDI-TOF MS was employed for rapid and reliable identification of Dickeya spp. in the plant-tissue-containing sample. It was found that the presence of plant tissue did not affect the results, making the proposed procedure very promising with respect to the fast and reliable detection and identification of bacteria in plant-tissue-containing samples.

Isolation of quaternary benzo[c]phenanthridine alkaloids from Macleaya microcarpa (MAXIM.) FEDDE: comparison of maceration, Soxhlet extraction and pressurised liquid extraction.

INTRODUCTION: Macleaya microcarpa (Papaveraceae family) has been of considerable interest in recent years as a prospective source of quaternary benzo[c]phenanthridine alkaloids (QBAs) related to many pharmaceutical beneficial effects. For this purpose, a quantitative, efficient and fast method to isolate the QBAs from the plant material is required. OBJECTIVE: To optimise and compare pressurised liquid extraction (PLE) with Soxhlet extraction and maceration in order to estimate extraction conditions for fast and efficient isolation of QBAs contained in the roots of Macleaya microcarpa. METHODOLOGY: The QBAs were extracted by PLE, Soxhlet extraction and maceration at different conditions (solvent, time, etc.). Reversed phase HPLC with diode-array detector was utilised for their determination and quantification. To optimise the PLE procedure, the variable parameters, including temperature (40-150 °C), sample-to-inert material ratio, extraction time (5-30 min) and number of extraction cycles (1-4), were also tested. RESULTS: Quantitative determination of QBAs resulted in 0.2-2.8 mg/g, 0.3-2.5 mg/g and 0.3-3.1 mg/g for PLE, Soxhlet extraction and maceration. To produce the yields mentioned above, PLE required only up to 30 min compared with 21 h for Soxhlet extraction and 49 days for maceration. CONCLUSION: PLE provided an effective and fast extraction of QBAs from M. microcarpa roots and can be recommended as an alternative isolation method to conventional techniques for QBAs from the plant sources.

Sensitive identification of milk protein allergens using on-line combination of transient isotachophoresis/micellar electrokinetic chromatography and capillary isoelectric focusing in fused silica capillary with roughened part.

A method for on-line concentration of milk proteins from large sample volumes using combination of transient isotachophoresis (tITP) and micellar electrokinetic chromatography (MEKC) in fused silica capillary with an inner roughened part has been developed. The method utilizes reversible dynamic adsorption of proteins onto a thin layer of PEG 4000 on the roughened surface of the capillary. In addition, the tITP/MEKC method was combined with capillary isoelectric focusing (CIEF) for on-line concentration, separation, identification and sensitive determination of proteins in skimmed milk. The method allows analysis of up to 50 µL of sample. This study has focused on the four important whey proteins, bovine serum albumin (BSA), α-lactalbumin (α-LA), and two genetic variants of ß-lactoglobulin (ß-LG A and ß-LG B). The proteins were identified on the basis of their migration times and characteristic pI values. The pI values of BSA, α-LA, ß-LG A, and ß-LG B were determined as 4.7, 4.4, 5.1, and 5.2, respectively. Limits of detection for BSA, α-LA and both ß-LG variants were found as 1.2, 1.0 and 1.0 pg mL-1, respectively. The linearity of calibration curves was characterized by the R2 = 0.9982. The method provided highly reproducible results as the relative standard deviations of the migration times and peak areas of the examined proteins did not exceed 1.6%.