Abstract:Invasion of pathogenic microorganisms and cell damage lead to abnormal accumulation of DNA in the cytoplasm. Cyclic GMP-AMP synthase (cGAS) catalyzes the generation of second messenger 2", 3"-cGAMP by recognizing DNA in the cytoplasm, transmitting signals to downstream stimulators of interferon gene (STING). STING induces the translocation of transcription factors IRF3 and NF-κB into the nucleus to express and secrete inflammatory factors such as type I interferon, which activate the body"s innate and adaptive immune responses. Many studies have indicated that disturbance of cGAS-STING pathway regulation leads to the occurrence and development of various diseases such as microbial infection, tumor and autoimmune diseases. Therefore, the development of drugs targeting cGAS and STING proteins is of great clinical value. This paper reviews the latest research progress of cGAS-STING pathway and its roles in different diseases, and summarizes the small-molecule compounds that have been reported to regulate cGAS and STING, in order to provide theoretical reference for future cGAS-STING pathway-related drug discovery.

Abstract:Extracellular signal-regulated kinase (ERK) is a kind of serine/threonine protein kinase. As a key downstream protein in RAS-RAF-MEK-ERK signaling pathway, its abnormal activation plays an important role in the development of tumors. Selective ERK1/2 inhibitors can block ERK signaling pathway while overcoming drug resistance caused by upstream target mutation. In this paper, the components of MAPK signaling pathway, the structure and functions of ERK and the role of ERK signaling pathway in tumor development are summarized, and some representative ERK inhibitors in clinical or preclinical studies are emphasized.

Abstract:As a new member of two-dimensional materials, black phosphorus has shown good application prospects in the fields of photoacoustic imaging, photothermal photodynamic therapy, and drug loading due to its excellent characteristics such as good biodegradability, biocompatibility, thickness-dependent tunable direct band-gap, and high surface-to-mass ratio. Because black phosphorus has the characteristics of easy oxidation and degradation, it is coated with relatively stable liposomes or polymeric materials to construct a black phosphorus-based drug delivery system, which shows great potential in tumor treatment and diagnosis and has become a new focus in drug delivery research. In this paper, we introduce the role of black phosphorus in tumor diagnosis and treatment in detail, and summarize the design of black phosphorus-based drug delivery system in recent years as well as its research progress in tumor diagnosis and treatment, in order to provide reference for the research and application of black phosphorus.

Abstract:The incidence of liver disease is increasing year by year. Due to the complex predisposing factors and unclear pathogenesis of liver diseases, the cure rate is still not ideal, so it is urgent to clarify its mechanism to find more effective therapeutic targets and drugs. Long non-coding RNA (lncRNA), as a non-coding RNA with a length of more than 200 nt, is a research hotspot in liver diseases in recent years. Focusing on the main signal transduction pathways in liver diseases, this review mainly summarizes the latest research progress of lncRNA in regulating liver disease-related signaling pathways, and elaborates that lncRNAs participate in various physiological processes such as cell proliferation, apoptosis, invasion, and migration by regulating key signaling pathways in liver diseases, thereby promoting the occurrence and development of liver diseases. This review provides new ideas for studying the mechanism of liver diseases, and new directions for finding new targets and biomarkers for the treatment of liver diseases.

Abstract:To identify novel inhibitors targeting the polo-box domain of polo-like kinase 1 (Plk1 PBD), a series of new peptidomimetics (7a-7u) without phosphate group were designed and synthesized, where the phosphate group in the structure of the selective Plk1 PBD inhibitor PLHSpT was replaced by the carboxyl group, and the unnatural amino acids were applied for further modification and optimization. The 21 peptidomimetic compounds designed and synthesized had a strong inhibitory effect on Plk1 PBD, of which compound 7l highly selectively inhibited Plk1 PBD with IC₅₀ of 0.285 μmol/L. The growth inhibition effect of HeLa tumor cell lines in vitro was better than that of compounds containing phosphate group. Moreover, the stability of the compound in rat plasma was improved by unnatural amino acids. Thus it is proved that selective Plk1 PBD inhibitor with improved characters can be obtained by replacing the phosphate group with a carboxyl group and restructuring the peptide chain.

Abstract:Flavaspidic acid AB is a bicyclic phloroglucinol derivative with various biological activities in Dryopteris fragrans (L.) Schott. The structure of flavaspidic acid AB was analyzed by inverse synthesis techniques, and its synthesis was designed under the principle of association. Using phloroglucinol as raw material, the 2-methyl-4-butyrylphloroglucinol was synthesized by Vilsmeier-Haack reaction, reduction and acylation, and the flavaspidic acid fragment was synthesized by acylation, alkylation and deacylation, after which N, N-dimethylmethyleneammonium iodide was activated and the flavaspidic acid AB was obtained. The structures of intermediates and flavaspidic acid AB were confirmed by MS, ¹H NMR and ¹³C NMR, and the yield of the target product reached 14.7%. Results indicate that the designed synthetic route of flavaspidic acid AB is simple and easy.

Abstract:To mask the bitterness of azithromycin（AZI） and improve patient compliance, an AZI-loaded microsphere (AZI-EC MS) for oral administration was prepared by O/W emulsion solvent evaporation with ethylcellulose (EC) as carrier. The release profiles and taste-masking effect of AZI-EC MS were preliminarily assessed. Its physical properties and morphology were then investigated by differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The results indicated that the polymer weight of EC could influence the drug release behavior. With a drug polymer ratio of 1∶1 and mixed EC (N22/T10, 7∶3) as carrier, the cumulative release of AZI-EC MS at 0.5 h was less than 40% and reached 90% at 8 h; the drug loading efficiency of microspheres was (48.95 ± 0.86)% with smooth spherical morphology. The AZI bitterness threshold is 9.93 μg/mL with a strong bitter taste, which indicated a better taste masking effect. Therefore, AZI-EC MS prepared in this study can mask AZI bitterness and improve patient compliance, setting the stage for the research of new AZI preparations.

Abstract:A quantitative analysis method based on solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS) for simultaneous determination of illicit drugs and their metabolites in wastewater was established. Samples filtered at pH of 2 and spiked with internal standard were loaded to Oasis Prime MCX cartridges for solid-phase extraction. The samples were washed with 4 mL of methanol and eluted with 4 mL of 5% ammonia in acetonitrile before reconstituting with 0.1% formic acid/water solution. ZORBAX Eclipse Plus C₁₈ column was used for chromatography, and gradient elution was performed with 0.1% formic acid/water solution and acetonitrile as mobile phase. The samples were then detected by electrospray ionization (ESI) in positive ion mode, and multiple reaction monitoring mode (MRM) was adopted for quantitative analysis. All analytes had a good linear relationship (r ≥ 0.993 2) within the range of their respective standard curve; the limit of quantification was 1 ng/L (except amphetamine at 2.5 ng/L); the extraction recovery ranged from 82.13% to 99.96%; and the intra- and inter-day precisions were less than 9.43%. The method is accurate, reliable and reproducible, and is suitable for the quantitative determination of illicit drugs and their metabolites in wastewater and can provide an analytical method for real-time monitoring of drug abuse.

Abstract:This study aimed to identify the related substances of midazolam hydrochloride by liquid chromatography-mass spectrometry (LC-MS). To separate the related substances of midazolam hydrochloride, gradient elution was performed using acetonitrile and 25 mmol/L of ammonium acetate (pH was adjusted to 5.5 with acetic acid) as mobile phase on Thermo BDS Hypersil C₁₈ column (100 mm × 4.6 mm, 2.4 μm). The accurate mass and elemental composition of the parent ions and their product ions of related substances were determined by electrospray-ionization quadrupole time-of-flight mass spectrometry (ESI-Q-TOF/MS). The structures of the related substances were identified by spectral analysis and process synthesis, and some of them were further confirmed by reference substances. Under the established HPLC condition, midazolam hydrochloride and its related substances were adequately separated, and 22 major related substances were detected and identified by hyphenated techniques in midazolam hydrochloride and its stressed samples, of which 8 were recorded as impurities in the United States Pharmacopeia. The LC-MS techniques can effectively separate and identify the related substances of midazolam hydrochloride and provide reference for the establishment of storage condition, optimization of synthetic processes and quality control.

Abstract:To explore the effect of Ginkgo biloba extract (GBE) on anticoagulation of 4 new oral anticoagulants (NOACs), dabigatran, apixaban, rivaroxaban and edoxaban in vitro, thrombin time (TT), prothrombin time (PT), activated partial thrombin time (APTT) and the activity of coagulation factor Xa (FXa) of rat plasma were measured at different concentrations of NOACs, GBE or NOACs combined with GBE, respectively. The results showed that TT, PT and APTT were prolonged with the increase of NOACs concentration in the range of 0-500 ng/mL; that except for TT of rivaroxaban, other results showed a good linear correlation with NOACs concentration (r²= 0.78-0.98); and that FXa activity decreased with increased concentration of FXa inhibitors (apixaban, rivaroxaban and edoxaban), with a good linear correlation with concentration of FXa inhibitors in the range of 0-250 ng/mL (r²= 0.85-0.94). GBE had no significant effect on TT, PT and APTT (P>0.05) in the concentration range of 0-500 μg/mL, but FXa activity had a positive linear correlation with GBE concentration (r²= 0.840 4). TT was prolonged with increasing GBE concentration when dabigatran was combined with GBE. When the above FXa inhibitors were combined with GBE, TT shortened and FXa activity increased with rising GBE concentration. There were no significant changes in PT and APTT (P>0.05) when NOACs were combined with GBE. The study results suggest that GBE may synergize with the anticoagulant activity of dabigatran and antagonize the anticoagulant activity of FXa inhibitors, possibly due to its role in increasing FXa activity.

Abstract:This study aimed to investigate whether β-elemene could improve the dysfunction of vascular endothelial cells induced by low shear force (LSS), and the proliferation and migration of vascular smooth muscle cells induced by oxidized low-density lipoprotein (ox-LDL). Parallel plate flow chambers and ox-LDL were used to establish vascular endothelial cells (ECs) dysfunction model and vascular smooth muscle cell (VSMCs) proliferation and migration model, respectively, and the effects of β-elemene on ECs dysfunction and VSMCs proliferation and migration were examined. The activity of ROS in ECs was measured by DHE and the activity of NO in ECs was tested by DAF-FM DA. The protein phosphorylation of Akt and ERK in ECs were detected by Western blot. The proliferation of VSMCs was measured by MTT. The migration of VSMCs was examined by cell scratch test and Transwell assay. The gene expression of MMP-2 and MMP-9 in VSMCs was measured by RT-qPCR. In ECs, β-elemene could significantly reduce the LSS-induced increase in ROS, significantly increase the LSS-induced decrease in NO, decrease the phosphorylation of ERK, and increase the phosphorylation of Akt. In VSMCs, β-elemene could significantly reduce the proliferation and migration of VSMCs induced by ox-LDL, and reduce the gene expression of MMP-2 and MMP-9. To conclude, β-elemene can improve the LSS-induced ECs dysfunction and ox-LDL-induced VSMCs proliferation and migration.

Abstract:Naturally split Npu DnaE intein can mediate rapid trans-splicing and C-cleavage, which is of great use in many aspects of protein engineering. However, the degradation of NpuC during expression and purification reduces the yield and purity of recombinant protein. N2C, an extended NpuN2-containing N-terminal NpuC fragment, was constructed to improve NpuC stability. N2C was expressed in BL21(DE3) and purified by affinity chromatography. The degradation ratio was calculated by ImageJ, and the factors affecting the C-terminal cleavage reaction of intein, such as temperature, DTT concentration and N/C ratio, were also investigated. The results showed that N2C lowered the proportion of degradation to 2.7%-7.2% and the yield of C-terminal cleavage reached 90% in 30 min at 37 °C with an N/C ratio of 5∶1 catalyzed by 1 mmol/L DTT. N2C can not only improve the stability of NpuC in Escherichia coli expression system, but also retain the activity of C-terminal cleavage reaction, which is of great significance for its application in protein purification.

Abstract:To compare the effects of endogenous 3-nitrotyrosine and non-natural 4-nitrophenylalanine in PD-L1 vaccine on the differentiation of T cell subsets, two immunogenic amino acids were introduced into the same site of PD-L1 vaccine. Two PD-L1 mutants with 3-nitrotyrosine and 4-nitrophenylalanine were obtained, respectively, using genetic code expansion technology. Mice were immunized with these two mutants, and their effects on the differentiation of T cell subsets in spleen were analyzed. The results of flow cytometry showed that the introduction of 4-nitrophenylalanine in PD-L1 vaccine could promote the polarization of Th1 cells while reducing the proportion of Treg cells; the introduction of 3-nitrotyrosine had no effect on the polarization of Th1 cells, while significantly increasing the proportion of Treg and Th17 cells. The introduction of both into PD-L1 vaccine could promote the response of CD8⁺ T cells in spleen, and the response of PD-L1 mutant containing 4-nitrophenylalanine was stronger. In summary, the non-natural 4-nitrophenylalanine is more suitable for the design of tumor vaccines as compared with endogenous 3-nitrotyrosine.

Abstract:Conformational restriction has become one of the important strategies for modification and optimization of lead compounds in structure-based drug design. In this review, we select some recent practical examples from literature to present applications of conformational restriction in structure-based drug design. By introducing fused rings, macrocycles, spiral rings, cyclopropyl groups, bridging rings, methyl groups into molecules, we can find that the conformational restriction strategy is widely used in improving pharmacokinetic properties, enhancing the activity and selectivity, and increasing the novelty of compounds. By using these conformational restriction strategies, the drug-like properties of lead compounds can be significantly improved. This paper can help to provide theoretical guidance and practical experience for innovation in drug design and development.

Abstract:Proteomics is one of the most advanced fields and hotspots in the research of various diseases in recent years. Its development has provided a new research direction for the early diagnosis and treatment of diabetes and has achieved some research results. Early diagnosis is helpful to control the progression of the disease or even avoid surgical treatment, which is of great significance for improving the prognosis of patients. This paper reviews the current status and prospects of proteomic technology and its applications in diabetes as well as its complications with a prospect of the impact of the rapid development of proteomics on diabetes and its positive role in discovering more diabetes biomarkers. In the future research, more attention should be paid to the interconnections between biomarkers.

Abstract:Circular RNA (circRNA) is a novel type of non-coding RNA with covalently closed loops which plays an important role in the occurrence and development of type 2 diabetes. In this paper, the relationship between circRNA and type 2 diabetes in terms of the regulation of pancreatic β-cell function by circRNA and the metabolic activity of heart, kidney and other organs is reviewed, and the possibility of circRNA as a clinical diagnostic marker for type 2 diabetes and its complications is emphasized, hoping to provide reference and clues for the prevention, diagnosis and treatment of type 2 diabetes.