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Sample preparation, including extraction, separation, and purification, is a vital process for natural product analysis. As an attractive sample pretreatment method, magnetic solid‐phase extraction (MSPE) has gained plenty of attention, mainly due to its simpler operation, less consumption of organic solvents, and shorter processing time than traditional SPE. This updated review is devoted to summarizing the applications of MSPE based on different magnetic nanomaterials in the analysis of various natural products in complex matrixes, such as biological samples, plants, and Chinese herbal preparations in the past four years (2020–2023). The preparation and fabrication of different materials are briefly introduced. Furthermore, the extraction mechanism and interaction forces between adsorbent and analytes are elaborated, and the advantages and disadvantages of different adsorbents coupled with various analytical methods for MSPE of different natural products are summarized. Moreover, the future trends and opportunities for MSPE in the natural product analysis are discussed. It is expected that this work can provide updated information for future research on the applications of MSPE in such fields. [ABSTRACT FROM AUTHOR]

Mussel‐inspired polydopamine has been widely used in capillary electrophoresis as a facile and universal tool for the surface modification of capillary, mainly due to its versatility, stability, strong adhesiveness, and biocompatibility properties. In this review, the recent development of mussel‐inspired surface chemistry with rapid deposition of polydopamine was introduced, and the recent applications of polydopamine in capillary electrophoresis (2011–July 2018) were summarized into four main aspects, namely, sample pretreatments, functional coatings, codeposition coatings, and intermediate coatings. Further study may be focused on clarifying the mechanisms of polydopamine formation and polydopamine‐assisted codeposition, and expanding coatings methods to plant polyphenols. [ABSTRACT FROM AUTHOR]

Hydrophilic interaction liquid chromatography, an alternative liquid chromatography mode, is of particular interest in separating hydrophilic and polar ionic compounds. Compared with traditional liquid chromatography techniques, hydrophilic interaction liquid chromatography offers specific advantages mainly including: (1) relatively green and water-soluble mobile phase composition, which enhances the solubility of hydrophilic and polar ionic compounds; (2) no need for ion-pairing reagents and high content of organic solvent, which benefits mass spectrometry detection; (3) high orthogonality to reverse-phase liquid chromatography, well adapted to two-dimensional liquid chromatography for complicated samples. Therefore, hydrophilic interaction liquid chromatography has been rapidly developed in many areas over the past decades. This review summarizes the recent progress (from 2012 to July 2016) of hydrophilic interaction liquid chromatography in pharmaceutical analysis, with the focus on detecting chemical drugs in various matrices, charactering active compounds of natural products and assessing biotherapeutics through typical structure unit. Moreover, the retention mechanism and behavior of analytes in hydrophilic interaction liquid chromatography as well as some novel hydrophilic interaction liquid chromatography columns used for pharmaceutical analysis are also described. [ABSTRACT FROM AUTHOR]

A magnetic porous carbon NH2‐MIL‐101‐C was synthesized through a one‐step carbonization process using NH2‐MIL‐101(Fe) as the precursor. The morphology, structure, magnetic behavior, and porosity of the as‐prepared NH2‐MIL‐101‐C were characterized. The results show that NH2‐MIL‐101‐C has a high Brunauer‐Emmett‐Teller surface area (213.7 m2/g), a large pore volume (0.2 m3/g), and a good magnetic property (23.4 emu/g). The NH2‐MIL‐101‐C was first used as a magnetic solid‐phase extraction adsorbent for the extraction of five anthraquinones from rhubarb. The main parameters that will affect the extraction efficiency were investigated. Under the optimized conditions, good linearity for the five anthraquinones was obtained with the R2 higher than 0.9910. The limits of detection and limits of quantitation for the analytes are 0.018−0.042 and 0.050−0.140 μg/mL, respectively. [ABSTRACT FROM AUTHOR]

This work describes a simple and reliable colorimetric method based on the gold nanoparticles without any modification, which can realize the rapid, sensitive, and quantitative detection of lead (Pb2+) and copper (Cu2+) ions, providing a reference for monitoring metal ions in the environmental water. When Pb2+ was added to the gold nanoparticles solution containing a low concentration of L‐Cysteine, the combination of Pb2+ and L‐Cysteine can induce the aggregation of gold nanoparticles. On the contrary, Cu2+ can catalyze the oxidation of L‐Cysteine and destroy the formation of the Au‐S bond between L‐Cysteine and gold nanoparticles, thereby preventing the aggregation of gold nanoparticles. As the ultraviolet‐visible spectrum of gold nanoparticle solution is closely related to their aggregation status, the Cu2+ and Pb2+ can be determined. The calibration curves, which are constructed based on ratios of the absorbance at 650 nm and 520 nm of gold nanoparticles, display good linearity in the range of 50.0−2.5 × 103 nM for Pb2+ and 25.0−300.0 nM for Cu2+, respectively. The limits of quantitation of Pb2+ and Cu2+ are determined to be 50.0 and 25.0 nM, respectively. In addition, the spiked recoveries of Pb2+ and Cu2+ in real water samples are 94.6−112.5 and 87.3−114.7% with a relative standard deviation of less than 6.3%, respectively. [ABSTRACT FROM AUTHOR]

In this work, a magnetic octahedral metal‐organic framework (Fe3O4@NH2‐MIL‐101(Fe)) was synthesized for the magnetic solid‐phase extraction of three anthraquinones, including aloe‐emodin, emodin, and physcion, in rhubarb. The Fe3O4@NH2‐MIL‐101(Fe) exhibits a high specific surface area of 259.2 m2/g with an average pore size of 6.0 nm and high magnetic responsivity of 23.4 emu/g, which may be used as an adsorbent for rapid preconcentration and separation of target analytes. The main parameters for magnetic solid‐phase extraction of anthraquinones, including the amount of adsorbent, extraction time, extraction temperature, extraction pH, elution solvent, and elution time, were systematically optimized. The whole extraction process requires a very low amount of adsorbent and a small volume of the sample. Besides, under the optimized conditions, the method shows satisfactory spiked recovery for anthraquinones in the range of 93.3–109.1% and the limits of detection are 1.7–3.4 ng/mL. The relative standard deviations for intra‐ and inter‐day precision are 0.2–1.3% and 0.2–0.6%, respectively. The experimental results indicate that the developed method is feasible for the analysis of anthraquinones in rhubarb. [ABSTRACT FROM AUTHOR]

In this study, the poly (sodium 4‐styrenesulfonate)‐mediated calcium carbonate magnetic microspheres were prepared by a simple spontaneous biomimetic mineralization method to immobilize kallikrein. The immobilized kallikrein can be easily separated from the reaction mixture by an external magnet. The structural properties of the materials were studied by several characterization techniques. Subsequently, the immobilized kallikrein enzyme activity and stability were studied. Moreover, the inhibitory potency of ten natural compounds on kallikrein was evaluated by combining with capillary electrophoresis analysis. The immobilized kallikrein exhibited optimum pH and temperature at 7.5 and 75°C, respectively. After seven successive cycles, the immobilized kallikrein retained 82% of its initial activity. Furthermore, the Michaelis–Menten constant (Km) and the half‐maximal inhibitory concentration (IC50) of serine protease inhibitor on the immobilized kallikrein were determined to be 3.30 mM and 67.04 μM, respectively. In addition, berberine, evodine, coptisine, and jatrorrhizine among the ten natural compounds showed good inhibitory activity on the immobilized kallikrein, and their % of inhibition were (43.1 ± 1.7), (34.4 ± 1.9), (38.0 ± 1.7), and (28.5 ± 1.0)%, respectively. These results indicate that the biomimetic mineralization synthetic magnetic microsphere is an efficient method for kallikrein immobilization. [ABSTRACT FROM AUTHOR]

In this study, a zirconium terephthalate metal‐organic framework‐coated magnetic nanoparticle (UiO‐66@PA@PEI@Fe3O4) was synthesized for the extraction of berberine prior to high‐performance liquid chromatography analysis. The phytic acid, which could be grafted onto the magnetic nanoparticle through electrostatic interaction with the abundant amino groups of polyethylenimine, possesses outstanding metal ion coordination ability for the immobilization of metal‐organic frameworks UiO‐66. The physicochemical properties of the obtained nanoparticle were thoroughly investigated by a series of characterization techniques. Then, the factors that will affect the extraction efficiency and recovery of berberine were investigated. Results indicated that the material had good stability and reusability, and high adsorption capacity (50.01 mg/g) to berberine through single‐layer adsorption. In addition, a molecular docking study indicated that the interactions between the material and berberine were mainly π‐π stacking and hydrophobic interaction. Finally, the material was successfully applied to the extraction of berberine in Rhizoma Coptidis and Cortex Phellodendri extracts with the recoveries of 76.1% and 71.6%, respectively. [ABSTRACT FROM AUTHOR]

In this study, thrombin inhibitors in tea were characterized by combining thrombin inhibition assay of tea extracts with ultra high performance liquid chromatography–mass spectrometry based multivariate statistical analysis. The inhibitory activity on thrombin for ten tea samples were tested in vitro. Then, upon collecting and processing liquid chromatography‐mass spectrometry data, combined with the results of activity assays, principal component analysis, and orthogonal partial least squares discriminant analysis were applied to predict discriminate differential markers. Six of twelve predicted marker compounds were tentatively identified. Among them, epigallocatechin 3‐O‐gallate, epicatechin gallate, epigallocatechin and gallocatechin 3‐O‐gallate showed good inhibitory activity on thrombin with IC50 values of 5.033, 6.573, 6.704 and 6.842 mM, respectively. Moreover, molecular docking results indicated that these four active compounds could insert into the catalytic activity pocket of thrombin and the residue GLU192 may be their binding site. [ABSTRACT FROM AUTHOR]

In this study, a capillary electrophoresis‐based online immobilized enzyme microreactor was developed for evaluating the inhibitory activity of green tea catechins and tea polyphenol extracts on trypsin. The immobilized trypsin activity and other kinetic parameters were evaluated by measuring the peak area of the hydrolyzate of chromogenic substrate S‐2765. The results indicated that the activity of the immobilized trypsin remained approximately 90.0% of the initial immobilized enzyme activity after 30 runs. The value of Michaelis–Menten constant (Km) was (0.47 ± 0.08) mM, and the half‐maximal inhibitory concentration (IC50) and inhibition constant (Ki) of benzamidine were measured as 3.34 and 3.00 mM, respectively. Then, the inhibitory activity of four main catechins (epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate) and three tea polyphenol extracts (green tea, white tea, and black tea) on trypsin were investigated. The results showed that four catechins and three tea polyphenol extracts had potential trypsin inhibitory activity. In addition, molecular docking results illustrated that epigallocatechin gallate, epicatechin gallate, epicatechin, and epigallocatechin were all located not only in the catalytic cavity, but also in the substrate‐binding pocket of trypsin. These results indicated that the developed method is an effective tool for evaluating inhibitory activity of catechins on trypsin. [ABSTRACT FROM AUTHOR]

Capillary electrochromatography, which combined the high selectivity of high‐performance liquid chromatography and the high separation efficiency of capillary electrophoresis, is an attractive separation tool. In this review, the developments on monolithic and open tubular capillary electrochromatography during 2017 to August 2019 are summarized. Considering the development of novel stationary phases is the most active research field in capillary electrochromatography, monolithic capillary electrochromatography is classified according to the polymer‐based and hybrid monolithic columns, while open‐tubular capillary electrochromatography is categorized by cyclodextrin, silica, polymer, nanomaterials, microporous materials, and biomaterials‐based open tubular columns. [ABSTRACT FROM AUTHOR]

Abstract: For lead compound discovery from natural products, hollow fiber cell fishing with chromatographic analysis is a newly developed method. In this study, an adsorbed hollow fiber‐based biological fingerprinting method was firstly developed to discover potential platelet aggregation inhibitors from Danshen–Honghua decoction. Platelets were seeded on the fiber and their survival rate was tested. Results indicated that more than 92% platelets survived during the whole operation process. Ranitidine and tirofiban were used as positive and negative control respectively to verify the reliability of the presented approach. The main variables such as amount of extract and stirring time that affect the adsorbed hollow fiber‐based biological fingerprinting process were optimized, and the repeatability of this method was also investigated. Finally, 12 potential active compounds in Danshen–Honghua decoction were successfully detected using the established approach and structures for nine of them were tentatively identified by liquid chromatography with mass spectrometry analysis. In addition, the in vitro platelet aggregation inhibition test was carried out for five of the nine hit compounds, and three active components, namely, lithospermic acid, salvianolic acid A, and salvianolic acid B were confirmed. These results proved that the proposed method could be an effective approach for screening platelet inhibitors from plant extracts. [ABSTRACT FROM AUTHOR]

Nano-sized molecularly imprinted polymers for tiliroside were successfully prepared by a precipitation polymerization method. Acrylamide, ethylene glycol dimethacrylate, azobisisobutyronitrile, and acetonitrile/dimethyl sulfoxide were used as functional monomer, cross-linker, initiator, and porogen, respectively. The structural features and morphological characterization of tiliroside-imprinted polymers were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The adsorption experiments indicated that the tiliroside-imprinted polymers exhibited high selective recognition property to tiliroside. Scatchard analysis indicated that the homogeneous-binding sites were formed in the polymers. The selectivity test revealed that the adsorption capacity and selectivity of polymers to tiliroside was significantly higher than that of rutin, astragalin, and kaempferol. Finally, the tiliroside-imprinted polymers were employed as adsorbents in solid-phase extraction for the extraction of tiliroside from the ethyl acetate extract of the flowers of Edgeworthia gardneri (wall.) Meisn. The results demonstrated that the extraction recoveries of tiliroside ranged from 69.3 to 73.5% by using tiliroside-imprinted polymers coupled with solid-phase extraction method. These results indicated that the tiliroside-based molecularly imprinted solid-phase extraction method was proven to be an effective technique for the separation and enrichment of tiliroside from natural medicines. [ABSTRACT FROM AUTHOR]

The formation of Pb-O bond between Pb SP 2+ sp and L-Cysteine can induce significant aggregation of Au NPs (blue color), conversely, Cu can catalyze the oxidation of Cysteine and prevent the aggregation of Au NPs (pink color). DOI: 10.1002/sscp.202200019 The cover picture shows that the lead ion (Pb SP 2+ sp ) and copper ion (Cu SP 2+ sp ) in lake water are detected by UV-Vis analysis using gold nanoparticles (Au NPs) as the colorimetric probe. [Extracted from the article]