Screening of immune cell activators from Astragali Radix using a comprehensive two-dimensional NK-92MI cell membrane chromatography/C18 column/time-of-flight mass spectrometry system

Astragali Radix(AR)is a clinically used herbal medicine with multiple immunomodulatory activities that can strengthen the activity and cytotoxicity of natural killer(NK)cells.However,owing to the complexity of its composition,the specific active ingredients in AR that act on NK cells are not clear yet.Cell membrane chromatography(CMC)is mainly used to screen the active ingredients in a complex system of herbal medicines.In this study,a new comprehensive two-dimensional(2D)NK-92MI CMC/C18 column/time-of-flight mass spectrometry(TOFMS)system was established to screen for potential NK cell activators.To obtain a higher column efficiency,3-mercaptopropyltrimethoxysilane-modified silica was synthesized to prepare the NK-92MI CMC column.In total,nine components in AR were screened from this system,which could be washed out from the NK-92MI/CMC column after 10 min,and they showed good affinity for NK-92MI/CMC column.Two representative active compounds of AR,isoastragaloside Ⅰ and astragaloside IV,promoted the killing effect of NK cells on K562 cells in a dose-dependent manner.It can thus suggest that isoastragaloside Ⅰ and astragaloside Ⅳ are the main immunomodulatory components of AR.This comprehensive 2D NK-92MI CMC analytical system is a practical method for screening immune cell activators from other herbal medicines with immunomodulatory effects.

Development of a surface plasmon resonance biosensor for accurate and sensitive quantitation of small molecules in blood samples

Therapeutic drug monitoring(TDM)has played an important role in clinical medicine for precise dosing.Currently,chromatographic technology and immunoassay detection are widely used in TDM and have met most of the needs of clinical drug therapy.However,some problems still exist in practical applications,such as complicated operation and the influence of endogenous substances.Surface plasmon resonance(SPR)has been applied to detect the concentrations of small molecules,including pesticide residues in crops and antibiotics in milk,which indicates its potential for in vivo drug detection.In this study,a new SPR-based biosensor for detecting chloramphenicol(CAP)in blood samples was developed and validated using methodological verification,including precision,accuracy,matrix effect,and extraction recovery rate,and compared with the classic ultra-performance liquid chromatographyultraviolet(UPLC-UV)method.The detection range of SPR was 0.1-50 ng/mL and the limit of detection was 0.099±0.023 ng/mL,which was lower than that of UPLC-UV.The intra-day and inter-day accuracies of SPR were 98%-114% and 110%-122%,which met the analysis requirement.The results show that the SPR biosensor is identical to UPLC-UV in the detection of CAP in rat blood samples;moreover,the SPR biosensor has better sensitivity.Therefore,the present study shows that SPR technology can be used for the detection of small molecules in the blood samples and has the potential to become a method for therapeutic drug monitoring.

Environmentally sensitive fluorescent probes with improved properties for detecting and imaging PDEδ in live cells and tumor slices

Kirsten rat sarcoma viral oncogene homolog(KRAS)-phosphodiesterase-delta(PDEδ)is a promising target for antitumor drug discovery.Herein,highly efficient and environmentally sensitive fluorescent probes of PDEδ(DS-Probes)were rationally designed.As compared with the reported PDEδprobes,DS-Probes showed higher binding affinity and selectivity,which were able to conveniently and efficiently label PDEδin live cells as well as tumor tissues.Therefore,these fluorescent probes are expected to facilitate PDEδ-based mechanism elucidation,drug discovery and pathologic diagnosis.

In situ synthesis and unidirectional insertion of membrane proteins in liposome-immobilized silica stationary phase for rapid preparation of microaffinity chromatography

Cell membrane affinity chromatography has been widely applied in membrane protein(MP)-targeted drug screening and interaction analysis.However,in current methods,the MP sources are derived from cell lines or recombinant protein expression,which are time-consuming for cell culture or purification,and also difficult to ensure the purity and consistent orientation of MPs in the chromatographic stationary phase.In this study,a novel in situ synthesis membrane protein affinity chromatography(iSMAC)method was developed utilizing cell-free protein expression(CFE)and covalent immobilized affinity chromatography,which achieved efficient in situ synthesis and unidirectional insertion of MPs into liposomes in the stationary phase.The advantages of iSMAC are:1)There is no need to culture cells or prepare recombinant proteins;2)Specific and purified MPs with stable and controllable content can be obtained within 2 h;3)MPs maintain the transmembrane structure and a consistent orientation in the chromatographic stationary phase;4)The flexible and personalized construction of cDNAs makes it possible to analyze drug binding sites.iSMAC was successfully applied to screen PDGFRβinhibitors from Salvia miltiorrhiza and Schisandra chinensis.Micro columns prepared by in-situ synthesis maintain satisfactory analysis activity within 72 h.Two new PDGFRβinhibitors,salvianolic acid B and gomisin D,were screened out with KD values of 13.44 and 7.39μmol/L,respectively.In vitro experiments confirmed that the two compounds decreasedα-SMA and collagen Ⅰ mRNA levels raised by TGF-βin HSC-T6 cells through regulating the phosphorylation of p38,AKT and ERK.In vivo,Sal B could also attenuate CCl_(4)-induced liver fibrosis by downregulating PDGFRβdownstream related protein levels.The iSMAC method can be applied to other general MPs,and provides a practical approach for the rapid preparation of MP-immobilized or other biological solid-phase materials.

Microfluidic adhesion analysis of single glioma cells for evaluating the effect of drugs

Cancer metastasis is one of the most serious problems for tumor therapy,which is closely related to cell adhesion and deadhesion process.Better comprehension of cell adhesion ability will benefit drug research.Here,a biomimetic microfluidic enzyme digestion method was proposed to gently measure the influence of drugs on cell-matrix adhesion ability at the single cell level.The method can selectively digest the extracellular matrix(ECM)that linked to a single cell,and the trypsin concentration around the cell is relatively uniform and constant,thus the measured cell adhesion strength should be precise.Commercially available anti-cancer agents including 5-fluorouracil(5-FU),actinomycin D(Act D),temozolomide(TMZ)and allicin were evaluated,and the data showed only TMZ and allicin can inhibit cell adhesion significantly under our experiment conditions.The influence of TMZ became more and more obvious as the increase of duration and the effect became prominent only after 6 h adhesion process,which could provide a quick evaluation of whether the drugs are effective to cancer cell(compared with Calcein-AM/PI cell viability test).The adhesion strength of U87 cells decreased when the concentration of TMZ increased,and the effect of TMZ can be effectively inhibited by adding lactic acid to culture medium,which indicated acidic tumor microenvironment could promote drug resistance of tumor cells.Different from conventional evaluation methods which focus on the drugs’influence on cellular viability or metabolism,this work provides a new perspective to study the effect of drugs,which is helpful to enrich the drug evaluation system.

Screening potential P-glycoprotein inhibitors by combination of a detergent-free membrane protein extraction with surface plasmon resonance biosensor

P-glycoprotein(P-gp)highly expressed in cancer cells can lead to multidrug resistance(MDR)and the combination of anti-cancer drugs with P-gp inhibitor has been a promising strategy to reverse MDR in cancer treatment.In this study,we established a label-free and detergent-free system combining surface plasmon resonance(SPR)biosensor with styrene maleic acid(SMA)polymer membrane proteins(MPs)stabilization technology to screen potential P-gp inhibitors.First,P-gp was extracted from MCF-7/ADR cells using SMA polymer to form SMA liposomes(SMALPs).Following that,SMALPs were immobilized on an SPR biosensor chip to establish a P-gp inhibitor screening system,and the affinity between P-gp and small molecule ligand was determined.The methodological investigation proved that the screening system had good specificity and stability.Nine P-gp ligands were screened out from 50 natural products,and their affinity constants with P-gp were also determined.The in vitro cell verification experiments demonstrated that tetrandrine,fangchinoline,praeruptorin B,neobaicalein,and icariin could significantly increase the sensitivity of MCF-7/ADR cells to Adriamycin(Adr).Moreover,tetrandrine,praeruptorin B,and neobaicalein could reverse MDR in MCF-7/ADR cells by inhibiting the function of P-gp.This is the first time that SMALPs-based stabilization strategy was applied to SPR analysis system.SMA polymer can retain P-gp in the environment of natural lipid bilayer and thus maintain the correct conformation and physiological functions of P-gp.The developed system can quickly and accurately screen small molecule ligands of complex MPs and obtain affinity between complex MPs and small molecule ligands without protein purification.

Discovery of a Potent Botulinum Neurotoxin A Inhibitor ZM299 with Effective Protections in Botulism Mice

Botulinum neurotoxins serotype A(BoNT/A)is the deadliest toxins known to humans and the"Category A"agent for bioterrorism.Over the past 20 years,significant efforts have been put forth to develop effective inhibitors of BoNT/A.Unfortunately,few identified inhibitors possess noteworthy efficacy against BoNT/A in vivo.Here,we performed a high-throughput virtual screening based on the structure-based docking simulations and found a novel potent scaffold 2-thionicotinate that inhibits the BoNT/A light chain(LC).We then synthesized and optimized a novel series of 2-thionicotinate derivatives and comprehensively evaluated their activity against BoNT/A in vitro and in vivo.An optimized compound ZM299 effectively exhibits anti-BoNT/A activity in primary neurons and displayed remarkably therapeutic efficacy against BoNT/A in vivo,which could raise the survival rate of intoxicated mice to 100%(12/12)after lethal doses of BoNT/A exposures.These findings demonstrate that 2-thionicotinates is a promising scaffold for producing more effective anti-BoNT/A analogs,and compound ZM299 is worthy of further preclinical evaluation as a drug candidate for the treatment of botulism.