Qi-Hui Zhang

A facile and versatile approach for controlling electroosmotic flow in capillary electrophoresis via mussel inspired polydopamine/polyethyleneimine co-deposition.

Electroosmotic flow (EOF), which reveals the charge property of capillary inner surface, has an important impact on the separation performance and reproducibility of capillary electrophoresis (CE). In this study, a novel, facile and versatile method to achieve diverse and controllable EOF in CE was reported based on the co-deposition of mussel-inspired polydopamine (PDA) and branched polyethyleneimine (PEI) on the capillary inner surface as the hybrid functional coating. After these PDA/PEI co-deposited columns were reinforced by the post-incubation of FeCl3, various magnitude and direction of EOF in CE could be easily achieved by varying a number of preparation parameters, including the mass ratio of DA/PEI and the molecular weight of PEI (including PEI-600, PEI-1800, PEI-10000 and PEI-70000). The separation effectiveness and stability of the hybrid coated columns were verified by the analysis of aromatic acids and aniline derivatives. The results showed that the controllable and diverse EOF was important in enhancing the separation performance of the analytes. The baseline separation of all the five aromatic acids can be achieved in 7 min with high separation efficiency by using the PDA/PEI-600 co-deposited column with the mass ratio of 6:1. On the other hand, with the PDA/PEI-70000 co-deposited column with the mass ratio of 6:1, the aniline compounds were easily baseline separated within 10 min. By contrast, using the bare and PDA coated columns, the migration of the aromatic acids was very slow and the baseline separation of the aniline compounds cannot be obtained. Moreover, the co-deposited columns showed long lifetime and good stability. The relative standard deviations for intra-day, inter-day and capillary-to-capillary repeatability of the PDA/PEI-600 co-deposited column with the mass ratio of 6:1, which was reinforced by the post-incubation of FeCl3, were all lower than 5%.

Determination of American ginseng saponins and their metabolites in human plasma, urine and feces samples by liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

American ginseng is a commonly consumed herbal medicine in the United States and other countries. Ginseng saponins are considered to be its active constituents. We have previously demonstrated in an in vitro experiment that human enteric microbiota metabolize ginseng parent compounds into their metabolites. In this study, we analyzed American ginseng saponins and their metabolites in human plasma, urine and feces samples by liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS). Six healthy male volunteers ingested 1 g of American ginseng twice a day for 7 days. On day 7, biological samples were obtained and pretreated with solid phase extraction. The ginseng constituents and their metabolites were characterized, including 5 ginseng metabolites in plasma, 10 in urine, and 26 in feces. For the plasma, urine and feces samples, the levels of ginsenoside Rb1 (a major parent compound) were 8.6, 56.8 and 57.7 ng/mL, respectively, and the levels of compound K (a major metabolite) were 58.4 ng/mL, 109.8 ng/mL and 10.06 μg/mL, respectively. It suggested that compound K had a remarkably high level in all three samples. Moreover, in human feces, ginsenoside Rk1 and Rg5, Rk3 and Rh4, Rg6 and F4 were detected as the products of dehydration. Further studies are needed to evaluate the pharmacological activities of the identified ginseng metabolites.

Layer-by-layer self-assembly of polydopamine/gold nanoparticle/thiol coating as the stationary phase for open tubular capillary electrochromatography

Much attention has been paid to utilizing polydopamine (PDA) as the stationary phase in open-tubular capillary electrochromatography (OT-CEC) owing to its diverse properties, such as strong adhesion to various surfaces, latent reactivity toward amine and thiol groups and metal ion chelating/redox activities. In this study, a novel open-tubular capillary column coated with polydopamine/gold nanoparticles/thiols (PDA/Au NPs/thiols) has been fabricated based on the multiple properties of PDA for the first time. The capillary inner surface was firstly functionalized with a layer of PDA/Au NPs using the strong adhesive and metal ion redox properties of PDA. Thiols were then introduced and covalently reacted with the hybrid coating based on the Michael addition reaction of PDA and thiols and also Au–S bonds. Moreover, benefitting from the porosity of PDA, layer-by-layer (LBL) self-assembly was further applied to increase the amounts of stationary phase (Au NPs and thiols), which can significantly enhance the separation effectiveness and stability of the coated column. The formation of the PDA/Au NP/thiol coating in the capillary was confirmed and characterized by scanning electron microscopy (SEM), Energy Dispersive Spectrometry (EDS) and AFM (Atomic Force Microscopy). Then the separation effectiveness of the PDA/Au NP/thiol@capillary was verified by the separation of alkylbenzenes, which can achieve baseline separation easily with high column efficiency. In addition, the column showed long lifetime and good stability. The relative standard deviations (RSDs) for intra-day and inter-day repeatability of the PDA/Au NP/thiol@capillary were lower than 5%. Therefore, the layer-by-layer self-assembly of PDA/Au NPs/thiols on the capillary inner-surface could be an effective capillary modification strategy.

In Vivo Selective Capture and Rapid Identification of Luteolin and Its Metabolites in Rat Livers by Molecularly Imprinted Solid-Phase Microextraction

A method based on molecularly imprinted solid-phase microextraction (MIP-SPME) coupled with liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (QTOF-MS/MS) was developed for the detection of luteolin and its metabolites in vivo. The MIP-SPME fibers were first fabricated by dopamine and silane, and then luteolin MIPs-coated fibers were successfully prepared using luteolin, acrylamide (AM), and ethylene glycol dimethacrylate (EGDMA) as the template, functional monomer and cross-linker, respectively. The characterizations of polymers were analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and the Brunauer-Emmett-Teller method (BET). The properties involving adsorption and selective experiments were evaluated, and these results revealed that MIP fibers presented high adsorption capacity and selectivity to luteolin. Furthermore, the developed MIP-SPME coupled with the LC-QTOF-MS/MS method was adopted to capture and identify luteolin and its metabolites in rat livers in vivo, and eventually, apigenin, chrysoeriol, and diosmetin were rapidly identified as metabolites.

Molecularly imprinted polymer for the selective extraction of luteolin from Chrysanthemum morifolium Ramat.

In this work, luteolin-imprinted polymers were prepared by noncovalent precipitation polymerization for the first time. Their structural features and morphologies were analyzed by using Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The adsorption experiments revealed that the luteolin-imprinted polymers presented high selective recognition property to luteolin. The selectivity experiment showed that the adsorption capacity and selectivity of polymers to luteolin was higher than that of three structural analogs, including quercetin, isorhamnetin, and ombuin. Furthermore, an efficient method based on luteolin-imprinted polymers coupled with solid-phase extraction was developed for the pretreatment of luteolin from Chrysanthemum morifolium Ramat. The results demonstrated that the luteolin-imprinted polymers coupled with solid phase extraction method was proven to be a potentially competitive technique for the separation and enrichment of luteolin in complex samples such as Chinese patent medicines and biological samples.

Evaluation of affinity interaction between small molecules and platelets by open tubular affinity capillary electrochromatography.

In this paper, an open tubular affinity capillary electrochromatography (OT‐ACEC) was developed by physical adsorption of rabbit platelets on the inner surface of capillary. The interactions between small molecules include adenosine diphosphate (ADP) (positive control), protocatechuic acid (negative control) and seven natural products (salvianolic acid B, salvianic acid A sodium, hydroxysafflor yellow A, ferulic acid, chlorogenic acid, sinapic acid, caffeic acid) and platelets were evaluated by their retention factors and binding constants obtained based on peak‐shift assay. Then, the activities of anti‐platelet aggregation induced by thrombin (THR), ADP and arachidonic acid (AA) for those small molecules (except ADP) were evaluated by turbidimetric method. The results indicate that: (i) ADP, a platelet aggregation inducer, had strong interaction with platelet, while protocatechuic acid that had no inhibition on platelet aggregation behaved no specific interaction; (ii) there was a positive correlation between the anti‐platelet aggregation activities of small molecules and their interactions with platelet, generally those compounds with higher binding constants with platelet exhibited higher activities. Therefore, the OT‐ACEC method developed in the present study can be a potential method to evaluate affinity interactions between small molecules and platelets, so as to predict the biological activities such as anti‐platelet aggregation for the small molecules.

Simultaneous screening and analysis of antiplatelet aggregation active alkaloids from Rhizoma Corydalis

Abstract Context: The rising problem of atherosclerosis and ischemic heart disease emphasizes the need to look for new antithrombotic components with effective modes of action. Corydalis yanhusuo (Y.H. Chou & Chun C. Hsu) W.T. Wang ex Z.Y. Su & C.Y. Wu (Papaveraceae) (Rhizoma Corydalis) has been used in the traditional medicines for the treatment of cardiovascular disease. Objective: The antiplatelet aggregation compounds in Rhizoma Corydalis were screened to validate its traditional medicinal use. Material and methods: Total alkaloid extract (TAE) of Rhizoma Corydalis was obtained by refluxing 100 g Rhizoma Corydalis powder with 600 mL 70% ethanol, and purified by acidification (20% HCl) and alkalization (5 M NaOH) process. Potential antiplatelet aggregation compounds in TAE were screened by a method involving platelet bio-specific extraction and HPLC-DAD/LC–MS analysis. Further in vitro antiplatelet aggregation activity confirmation of TAE and seven main alkaloids were achieved by turbidimetry method within 3 h after blood collection from rabbit carotid artery, and all the test drugs were at the concentration range of 25–350 μg/mL. Finally, HPLC-DAD was employed for the quantitative determination of seven main components in TAE. Results: Five alkaloids, identified as glaucine, dehydrocorydaline, canadine, tetrahydrocoptisine and corydaline, can be specifically extracted with platelets. The results indicated that all these five alkaloids can inhibit thrombin-induced platelet aggregation in a low dose (IC50 of glaucine, dehydrocorydaline, canadine, tetrahydrocoptisine and corydaline were 49.057, 34.914, 33.547, 84.261 and 54.164 μg/mL, respectively) as compared to TAE (IC50 = 175.426 μg/mL) and aspirin (IC50 = 300.340 μg/mL), while the unbound compounds (palmatine and tetrahydropalmatine) had a very weak antiplatelet effect (IC50 > 200 μg/mL). Discussion and conclusion: This study is the first reported work for antiplatelet components screening in Rhizoma Corydalis. Seven compounds were detected and identified by HPLC-DAD/LC–MS, of which five platelet-targeted compounds were discovered.

Quercetin protects mouse liver against triptolide-induced hepatic injury by restoring Th17/Treg balance through Tim-3 and TLR4-MyD88-NF-κB pathway.

Abstract Triptolide (TP) is a diterpene triepoxide with various biological activities, but its clinical applications have been limited by potential hepatotoxicity, which can be attributed to T helper 17 (Th17)/T regulatory (Treg) cell imbalance. Quercetin (QE), a natural flavonoid, has been reported to have many benefits and medicinal properties, including hepatoprotective activity against TP‐induced liver injury. However, the hepatoprotection mechanisms have not been clarified. The present study was designed to explore the protective effect and the mechanism of QE against TP‐induced liver injury. Treatment with QE (20, 50 and 80 mg/kg) prior to TP administration restored TP‐induced alterations in a certain dose range indicating that QE was able to inhibit TP‐induced liver injury. One mechanism underlying this effect was the shifting balance in Th17 and Treg cells from Th17 dominance to Treg dominance. Furthermore, QE markedly decreased the expression level of the Th17‐related pro‐inflammatory cytokines interleukin (IL)‐17 and IL‐6, as well as the Th17 transcription factor retinoid‐related orphan receptor‐&ggr;t (ROR‐&ggr;t). TP induced downregulation in the expression of anti‐inflammatory cytokine IL‐10, but the expression of Treg transcription factor forkhead/winged‐helix family transcriptional repressor p3 (FoxP3) was restored by QE. In the process of exploring the possible hepatoprotective mechanisms of QE, we found that QE significantly reduced both protein and mRNA expression of Toll‐like receptor 4 (TLR4), which in turn not only inactivated myeloid differentiation primary response gene 88 (MYD88), nuclear factor kappa B (NF‐&kgr;B) and related inflammatory cytokines IL‐6 and IL‐17, but also simultaneously increased the levels of T‐cell immunoglobulin and mucin domain‐containing protein 3 (Tim‐3). Furthermore, blocking of TLR4 enhanced the effect of QE in regulating the Th17/Treg imbalance. In summary, this report has demonstrated for the first time that the protection afforded by QE against TP‐induced liver injury was associated with a shift in the balance of Th17 and Treg cells to Treg dominance, which was regulated by Tim‐3 and TLR4‐MyD88‐NF‐&kgr;B signaling pathway. Graphical abstract Figure. No Caption available. HighlightsQuercetin could protect liver injury induced by triptolide.Quercetin could restore Th17/Treg balance.The protective effect of Quercetin is mediated via Tim‐3 and TLR4‐MyD88‐NF‐&kgr;B pathway.

Epigallocatechin-3-gallate Prevents Triptolide-Induced Hepatic Injury by Restoring the Th17/Treg Balance in Mice.

Drug-induced liver injury (DILI) is the most common cause of acute liver failure. Disruption of the Th17/Treg balance can lead to hepatic inflammation, which causes the main symptoms of DILI. Here we investigate the protective mechanisms of (-)-Epigallocatechin-3-gallate (EGCG) on triptolide (TP)-induced DILI that shows the Th17/Treg imbalance. Pretreatment with EGCG (5[Formula: see text]mg/kg) for 10 days before TP (0.5[Formula: see text]mg/kg) administration in mice significantly reduced the increased alanine aminotransferase (ALT) level ([Formula: see text]) induced by TP treatment. The hepatic histology analysis further proved that EGCG protected mice from TP-induced liver injury. The imbalance of Th17/Treg was induced by TP treatment, as shown by the upregulation of TLR4 and downregulation of Tim3 expression. EGCG pretreatment can maintain the expression of TLR4 and Tim3 at normal levels to restore the Th17/Treg imbalance. In addition, EGCG can block the TP-induced expression of the downstream targets of TLR4, including MyD88, NF[Formula: see text]B, and retinoid related orphan receptor (ROR-[Formula: see text]t), while EGCG can restore the TP inhibition of forkhead/winged-helix family transcriptional repressor p3 (FoxP3) that is the downstream target of Tim3. Consequently, EGCG pretreatment can effectively inhibit the Th17-related pro-inflammatory cytokine (e.g. IL-17 and IL-6) upregulation induced by TP treatment. However, TP inhibition of Treg-related anti-inflammatory cytokine IL-10 production was restored by EGCG pretreatment. Taken together, these results suggest that EGCG possesses significant protective properties against TP-induced hepatic inflammatory injury, and that these properties are carried out via the restoration of the Th17/Treg imbalance by the inhibition of the TLR4 signaling pathway and the enhanced activation of the Tim3 signaling pathway.

In vitro screening and evaluation of 37 traditional chinese medicines for their potential to activate peroxisome proliferator-activated receptors-γ

Background: Peroxisome proliferator-activated receptors (PPAR)-γ is widely used as an attractive target for the treatment of type 2 diabetes mellitus. Thiazolidinediones, the agonists of PPARγ, has been popularly utilized as insulin sensitizers in the therapy of type 2 diabetes whereas numerous severe side-effects may also occur concomitantly. Objective: The PPARγ activation activity of different polar extracts, including petroleum ether, ethyl acetate, n-butanol, residual of ethanol, the precipitate part of water and the supernatant of water extracts, from 37 traditional Chinese medicines were systematically evaluated. Materials and Methods: HeLa cells were transiently co-transfected with the re-constructed plasmids of GAL4-PPARγ-ligand binding domain and pGL4.35. The activation of PPARγ by different polarity extracts were evaluated based on the PPARγ transactivation assay and rosiglitazone was used as positive control. Results: Seven medicines (root bark of Lycium barbarum, Anoectochilus sroxburghii, the rhizome of Phragmites australis, Pterocephalus hookeri, Polygonatum sibiricum, fruit of Gleditsia sinensis, and Epimedium brevicornu) were able to significantly activate PPARγ. Conclusion: As seven medicines were able to activate PPARγ, the anti-diabetic activity of them is likely to be mediated by this nuclear receptor.