Progress of Cell Membrane Chromatography and Its Application in Screening Active Ingredients of Traditional Chinese Medicine

Screening of CPT1A-Targeting Lipid Metabolism Modulators Using Mitochondrial Membrane Chromatography

Carnitine palmitoyltransferase 1A (CPT1A), which resides on the mitochondrial outer membrane, serves as the rate-limiting enzyme of fatty acid β-oxidation. Identifying the compounds targeting CPT1A warrants a promising candidate for modulating lipid metabolism. In this study, we developed a CPT1A-overexpressed mitochondrial membrane chromatography (MMC) to screen the compounds with affinity for CPT1A. Cells overexpressing CPT1A were cultured, and subsequently, their mitochondrial membrane was isolated and immobilized on amino-silica gel cross-linked by glutaraldehyde. After packing the mitochondrial membrane column, retention components of MMC were performed with LC/MS, whose analytic peaks provided structural information on compounds that might interact with mitochondrial membrane proteins. With the newly developed MMC-LC/MS approach, several Chinese traditional medicine extracts, such as Scutellariae Radix and Polygoni Cuspidati Rhizoma et Radix (PCRR), were analyzed. Five noteworthy compounds, baicalin, baicalein, wogonoside, wogonin, and resveratrol, were identified as enhancers of CPT1A enzyme activity, with resveratrol being a new agonist for CPT1A. The study suggests that MMC serves as a reliable screening system for efficiently identifying modulators targeting CPT1A from complex extracts.

Cell-based 3D bionic screening by mimicking the drug-receptor interaction environment in vivo

Most small-molecule drugs influence cell behavior through their interaction with one or more cellular proteins. The efficacy is unanticipated in the later stages of drug development if small-molecule drugs are discovered in the absence of a biological context. Bionic screening is an in vivo drug-receptor interaction platform that can identify small molecules with recognized activity, improving the likelihood of drug efficacy in the clinic. Here, we report the design of an innovative cell-based bionic screening system using 3D microcarrier cultures to simulate in vivo conditions and facilitate small-molecule drug discovery. Through its combination with HPLC/MS, the method can comprehensively identify small-molecule lead compounds in arbitrarily complex systems in an unbiased manner. In particular, cell-covered microcarriers provide a high-density of cells for affinity performance assessments in the absence of appreciable cell damage and maintain immunogenicity, the 3D structure of which is similar to tissue morphology in vivo, thereby mimicking in vivo drug-receptor interactions. The method is scalable, easy to handle, and requires minimal optimization across a range of different cell lines to realize high-throughput drug screening for the corresponding diseases. This provides a valuable tool for lead compound discovery in more physiologically relevant systems and may address the lack of clinically available drugs.

Construction of graphene quantum dots-decorated EGFR cell membrane chromatography for screening active components from Peucedanum praeruptorum Dunn

A novel stability-enhanced graphene quantum dot (GQD)-decorated epidermal growth factor receptor (EGFR) cell membrane chromatography was constructed to study the potential application of GQDs in bioaffinity chromatography, and to screen active components acting on EGFR from traditional Chinese medicine (TCM). The carboxyl groups on the surface of GQDs reacted with the amino groups of the amino-silica gel (SiO₂-NH₂) to form a covalent bond, thereby preparing the GQD-decorated silica gel (SiO₂-GQDs). The EGFR cell membrane was further immobilized on the SiO₂-GQDs through the same covalent binding method to obtain the GQD-decorated cell membrane stationary phase (SiO₂-GQDs-CMSP). In this way, the cell membrane was firmly immobilized on the decorated silica carrier. The life span and stability of the GQD-decorated cell membrane chromatographic (SiO₂-GQDs-CMC) column were both enhanced, and the optimal immobilization conditions of the EGFR cell membrane were also determined. This model was then verified by establishing a SiO₂-GQDs-CMC online liquid chromatography-ion trap-time-of-flight (LC-IT-TOF) system to screen possible active components in Peucedanum praeruptorum Dunn. As a result, praeruptorin B (Pra-B) was screened out, and its inhibitory effect against EGFR cell growth was evaluated by the cell counting kit-8 (CCK-8) assay. Molecular docking assay was also conducted to further estimate the interaction between Pra-B and EGFR. Overall, this research indicated that GQDs may be a promising nanomaterial to be used in prolonging the life span of the CMC column, and Pra-B could be a potential EGFR inhibitor so as to treat cancer.

Recent advances in screening active components from natural products based on bioaffinity techniques

Natural products have provided numerous lead compounds for drug discovery. However, the traditional analytical methods cannot detect most of these active components, especially at their usual low concentrations, from complex natural products. Herein, we reviewed the recent technological advances (2015–2019) related to the separation and screening bioactive components from natural resources, especially the emerging screening methods based on the bioaffinity techniques, including biological chromatography, affinity electrophoresis, affinity mass spectroscopy, and the latest magnetic and optical methods. These screening methods are uniquely advanced compared to other traditional methods, and they can fish out the active components from complex natural products because of the affinity between target and components, without tedious separation works. Therefore, these new tools can reduce the time and cost of the drug discovery process and accelerate the development of more effective and better-targeted therapeutic agents.

Development of 3-mercaptopropyltrimethoxysilane (MPTS)-modified bone marrow mononuclear cell membrane chromatography for screening anti-osteoporosis components from Scutellariae Radix

Osteoporosis is a bone metabolic disease caused by the imbalance between osteoblasts and osteoclasts due to excess osteoclastogenesis, manifesting in the decrease of bone density and bone strength. Scutellariae Radix shows good anti-osteoporosis activity, but the effective component is still unclear. Cell membrane chromatography (CMC) is a biological affinity chromatography with membrane immobilized on a silica carrier as the stationary phase. It can realize a dynamical simulation of interactions between drugs and receptors on cell membrane, which is suitable for screening active compounds from complex systems. In this study, the components of Scutellariae Radix with potential anti-osteoporosis activity through inhibiting the differentiation from bone marrow mononuclear cells (BMMCs) to osteoclast were screened by a BMMC/CMC analytical system. Firstly, a new 3-mercaptopropyltrimethoxysilane (MPTS)-modified BMMC/CMC stationary phase was developed to realize covalent binding with cell membrane fractions. By investigating the retention time (t_R) of the positive drug, the life span of the MPTS-modified CMC columns was significantly improved from 3 to 12 days. Secondly, 6 components of Scutellariae Radix were screened to show affinity to membrane receptors on BMMCs by a two-dimensional BMMC/CMC–TOFMS analytical system. Among them, tectochrysin demonstrated the best anti-osteoporosis effect in vitro, which has never been reported. We found that tectochrysin could inhibit the differentiation of BMMCs into osteoclasts induced by receptor activator of nuclear factor-κΒ ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) in a concentration-dependent manner in vitro. In vivo, it significantly reduced the loss of bone trabeculae in ovariectomized mice, and decreased the level of C-terminal cross-linking telopeptides of type 1 collagen (CTX-1), tartrate-resistant acid phosphatase 5b (TRAP-5b), interleukin 6 (IL-6) in serum. In conclusion, tectochrysin serves as a potential candidate in the treatment of osteoporosis. The proposed two-dimensional MPTS-modified BMMC/CMC-TOFMS analytical system shows the advantages of long-life span and fast recognition ability, which is very suitable for infrequent cell lines.

Covalent Design of Cell Membrane Stationary Phase with Enhanced Stability for Fast Screening P-Glycoprotein Inhibitors

Cell membrane chromatography (CMC) has been widely used for characterizing the interaction between drugs and membrane receptors to screen target components from herbal medicines. However, the column life, stability, and the efficiency cannot meet the needs of high-throughput screening purpose. In this study, a P-glycoprotein immobilized cell membrane stationary phase (P-gp/CMSP) was prepared with a simple and mild two-step aldehyde modification, realizing the covalent bonding between cell membrane and stationary phase. The column life and stability were significantly enhanced compared with the unmodified columns. The P-gp/CMC column was equipped into a comprehensive 2D P-gp/CMC/Capcell-C18/TOFMS system, which actualizes the automated and high-throughput analytical process and rapid identification of complex chemical samples with no data loss. Five compounds with significant retention were screened out and unambiguously identified by the comprehensive 2D analytical system. Baicalin was confirmed as a P-gp inhibitor with ATP depletion inhibition ratio of 83.4%. Moreover, the reversal index of baicalin on DOX significantly increased to 11.13 when its concentration reached 25 μM, revealing that baicalin could effectively reverse the MDR cell model induced by DOX. The integrated system is a practical drug discovery platform and could be applied to other transmembrane protein models.

Online coupling of the Ussing chamber, solid-phase extraction and high-performance liquid chromatography for screening and analysis of active constituents of traditional Chinese medicines

A semi-automated online platform was established successfully for preliminary screening of potential active flavonoids of traditional Chinese medicines (TCMs) in multicomponent system. Online coupling of the in vitro intestinal absorption model, solid phase extraction (SPE) and high-performance liquid chromatography (HPLC) was actualized at the first time. The Ussing chamber model was selected to absorb the constituents of TCMs. A mini chromatographic column filled with C18 was used as a SPE column for online enrichment of flavonoids. HPLC was applied to analyze the constituents screened by platform. With the use of rutin as a model flavonoid, the specifications of SPE column, eluting solvent, elution time and flow rate of eluent were systematically investigated to optimize online system. Under the optimal conditions, the linear range of rutin was 0.125-368 µg/mL with the correlation coefficient (R²) greater than 0.9947. The limit of detection (LOD) was as low as 0.0500 µg/mL and the limit of quantification (LOQ) was 0.125 µg/mL. The intra-day relative standard deviation (RSD) and inter-day RSD was 2.5% and 3.8%, respectively. The recoveries of rutin in the intestinal absorption samples ranged from 93.2% to 94.0%. Finally, the online system was applied to screen the potential active flavonoids of Scutellaria baicalensis Georgi (Huangqin, HQ) and Polygoni Cuspidati Rhizoma et Radix (Huzhang, HZ). A total of 14 flavonoids of these two TCMs were identified by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), and 12 flavonoids of them were screened as the potential active components by online Ussing chamber-SPE-HPLC. In comparison with offline method and gavage in rats, the online system can screen the active constituents from TCMs more accurately and completely. The results demonstrated that the online system was reliable and sufficiently accurate for screening and determination of the potential active flavonoids of TCMs in multicomponent system.