Ligand Fishing with Cellular Membrane-Coated Magnetic Beads: A New Method for the Screening of Potentially Active Compounds from Natural Products

Chitosan-based matrix solid-phase dispersion extraction assisted cell membrane magnetic bead ligand-affinity assay for screening active compounds from Fructus Cnidii

Cell membrane ligand-affinity assay is a useful tool for screening the active compounds from natural products. However, in traditional cell membrane ligand-affinity assays, natural products need to be refluxed, before being analyzed. This process consumes considerable time and energy and cannot be used for screening natural products that contain thermally unstable compounds. Therefore, an efficient analytical method is required. In this study, chitosan-based matrix solid-phase dispersion extraction was combined with cell membrane magnetic bead ligand-affinity assay to form a novel method for identifying the active compounds in Fructus Cnidii such as osthole and imperatorin. When compared with traditional cell membrane ligand-affinity assays, this assay requires less energy, extraction time (7 min), solvent volume (1.2 mL) and fewer natural products (40 mg). This indicates that the chitosan-based matrix solid-phase dispersion extraction assisted cell membrane magnetic beads ligand-affinity assay is an alternative analytical method for studying natural products. This article is protected by copyright. All rights reserved.

Application progress of immobilized biomembrane in the discovery of active compounds of natural products

Natural products (NPs) are an important source of bioactive compounds. Considering their complex matrix effects, the development of suitable methodologies for the fast identification and analysis of active substances from NPs played a significant role in controlling their quality and discovering new drugs. In recent years, the technology of immobilized biomembrane has attracted increasing attention, due to its peculiarities such as multi-target efficiency, accuracy and/or time-saving compared with traditional activity-guided separation and ligand fishing methods. This article first provides a systematic review of the latest advances in screening technologies based on biomembrane in the field of NPs. It includes detailed discussions of these technologies, including cell membrane chromatography, artificial membrane chromatography, cell membrane fishing, living cell fishing methods, and their applications in screening various active molecules from NPs. Their limitations and future development prospects were further discussed.

Ligand fishing via a monolithic column coated with white blood cell membranes: A useful technique for screening active compounds in Astractylodes lancea

The cell membrane-coated monolithic column (CMMC) ligand fishing assay is an interesting approach set up for the study of natural products (NPs). NPs such as Atractylodes lancea contain many compounds. Traditional methods used to separate compounds and determine active compounds by pharmacological tests are time-consuming and inefficient. Therefore, an alternative method is required to determine active compounds in NPs. Here, white blood cells were broken, and the white blood cell membranes (WBCMs) were immobilized on the surface of a monolithic column to form a CMMC. The column was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and confocal laser scanning microscopy. Combined with gas chromatography/mass spectrometry (GC/MS), the CMMC was used to screen active compounds in Atractylodes lancea. Three potential active compounds including hinesol, β-eudesmol, and 4-phenylbenzaldehyde were discovered. A molecular docking assay demonstrated that these compounds could bind to MD-2 laid on WBCMs. In addition, antiinflammatory effects by the discovered compound in vitro were confirmed, and β-eudesmol showed a concentration-dependent inhibitory effect on the tumor necrosis factor (TNF)-α of a RAW264.7 cell (P < 0.05). The CMMC ligand fishing assay exhibits good selectivity, great speed effects and is a potentially reliable tool for drug discovery in NPs.

An In Vitro Coumarin-Antibiotic Combination Treatment of Pseudomonas aeruginosa Biofilms

The drug resistance of Pseudomonas aeruginosa is a worldwide problem due to its great threat to human health. A crude extract of Angelica dahurica has been proved to have antibacterial properties, which suggested that it may be able to inhibit the biofilm formation of P. aeruginosa; initial exploration had shown that the crude extract could inhibit the growth of P. aeruginosa effectively. After the adaptive dose of coumarin was confirmed to be a potential treatment for the bacteria’s drug resistance, “coumarin-antibiotic combination treatments” (3 coumarins—simple coumarin, imperatorin, and isoimperatorin—combined with 2 antibiotics—ampicillin and ceftazidime) were examined to determine their capability to inhibit P. aeruginosa. The final results showed that (1) coumarin with either ampicillin or ceftazidime significantly inhibited the biofilm formation of P. aeruginosa; (2) coumarin could directly destroy mature biofilms; and (3) the combination treatment can synergistically enhance the inhibition of biofilm formation, which could significantly reduce the usage of antibiotics and bacterial resistance. To sum up, a coumarin-antibiotic combination treatment may be a potential way to inhibit the biofilm growth of P. aeruginosa and provides a reference for antibiotic resistance treatment.

Immobilization of cell membrane onto a glucose-Zn-based porous coordination polymer and its application to rapid screening of potentially active compounds from Vaccinium corymbosum L. leaves

A novel glucose-Zn-based porous coordination polymer (PCP) was selected as a carrier of cell membranes (CMs) to fabricate CM-coated PCP (CMPCP) for rapid screening of potentially active compounds from natural products. The cell disruption and the amount of maximum CMs adsorbed on PCP were optimized according to the amount of immobilized protein. This new kind of matrix exhibited good reproducibility and stability, and was applied for fishing potentially active compounds from the extracts of Vaccinium corymbosum L. leaves (VCL). Using LC-MS/MS, chlorogenic acid and quercetin were identified as the potentially active compounds through comparison of normal and non-alcoholic fatty liver disease (NAFLD)-modeled CMPCP. Our results suggested that the proposed approach based on CMPCP was environmentally friendly, cost-effective, and convenient in terms of green porous material, stable protein loading capacity, and accessible operation process. The developed method could provide a promising platform for efficient drug discovery from natural product resources.Graphical abstract.

Screening of the potentially active compounds from Polygonatum sibiricum using RAW264.7 cellular membranes coated magnetic beads fishing followed by HPLC analysis

Target biomolecule-immobilized magnetic beads could be used as a powerful tool for screening active compounds present in natural products. Low damage rates of the target proteins, associated with the availability of diverse automated online approaches for analysis, make it a valuable tool for affinity studies. RAW264.7 cells (a kind of murine macrophage cell line) were used in this study. These cellular membranes were immobilized onto the surface of MBs and were used for screening the active compounds of Polygonatum sibiricum. Combining this technique with HPLC led to the identification of an active compound and its biological activity was confirmed. This is the first report establishing the use of RAW264.7 cellular membrane-coated magnetic bead fishing followed by HPLC analysis for screening active compounds from natural products.

Solid-Supported Proteins in the Liquid Chromatography Domain to Probe Ligand-Target Interactions

Ligand-target interactions play a central role in drug discovery processes because these interactions are crucial in biological systems. Small molecules-proteins interactions can regulate and modulate protein function and activity through conformational changes. Therefore, bioanalytical tools to screen new ligands have focused mainly on probing ligand-target interactions. These interactions have been evaluated by using solid-supported proteins, which provide advantages like increased protein stability and easier protein extraction from the reaction medium, which enables protein reuse. In some specific approaches, precisely in the ligand fishing assay, the bioanalytical method allows the ligands to be directly isolated from complex mixtures, including combinatorial libraries and natural products extracts without prior purification or fractionation steps. Most of these screening assays are based on liquid chromatography separation, and the binding events can be monitored through on-line or off-line methods. In the on-line approaches, solid supports containing the immobilized biological target are used as chromatographic columns most of the time. Several terms have been used to refer to such approaches, such as weak affinity chromatography, high-performance affinity chromatography, on-flow activity assays, and high-performance liquid affinity chromatography. On the other hand, in the off-line approaches, the binding event occurs outside the liquid chromatography system and may encompass affinity and activity-based assays in which the biological target is immobilized on magnetic particles or monolithic silica, among others. After the incubation step, the supernatant or the eluate from the binding assay is analyzed by liquid chromatography coupled to various detectors. Regardless of the selected bioanalytical approach, the use of solid supported proteins has significantly contributed to the development of automated and reliable screening methods that enable ligands to be isolated and characterized in complex matrixes without purification, thereby reducing costs and avoiding time-laborious steps. This review provides a critical overview of recently developed assays.

Ligand fishing with cellular membrane-coated cellulose filter paper: a new method for screening of potential active compounds from natural products

Ligand fishing is a widely used approach for screening active compounds from natural products. Recently, cell membrane (CM) as affinity ligand has been applied in ligand fishing, including cell membrane chromatography (CMC) and CM-coated magnetic bead. However, these methods possess many weaknesses, including complicated preparation processes and time-consuming operation. In this study, cheap and easily available cellulose filter paper (CFP) was selected as carrier of CM and used to fabricate a novel CM-coated CFP (CMCFP) for the first time. The type of CFP was optimized according to the amount of immobilized protein, and the immobilization of CM onto CFP by the insertion and self-fusion process was verified by confocal imaging. The CMCFP exhibited good selectivity and stability and was used for fishing potentially active compounds from extracts of Angelica dahurica. Three potentially active compounds, including bergapten, pabulenol, and imperatorin, were fished out and identified. The traditional Chinese medicine systems pharmacology database and analysis platform was used to build an active compound-target protein network, and accordingly, the gamma-aminobutyric acid receptor subunit alpha-1 (GABRA1) was deduced as potential target of CM for the active compounds of Angelica dahurica. Molecular docking was performed to evaluate the interaction between active compounds and GABRA1, and bergapten was speculated as a new potentially active compound. Compared with other methods, the fishing assay based on CMCFP was more effective, simpler, and cheaper.

Screening techniques for the identification of bioactive compounds in natural products

Natural products (NPs) have a long history of clinical use and are rich source of bioactive compounds. The development of tools and techniques for identifying and analyzing NP bioactive compounds to ensure their quality and discover new drugs is thus very important and still in demand. Screening techniques have proven highly useful for screening and analyzing active components in complex mixtures, which rely on cell culture, dialysis, ultrafiltration, chromatographic methods and target molecule immobilization, using biological targets to identify the active compounds. The recent progress in biological screening techniques in the field of natural products is reviewed here. This includes a review on the strategy and application of the screening methods, their detailed description and discussion of their existing limitations of the different models along with prospective in future development of screening techniques.