Screening of aromatase inhibitors in traditional Chinese medicines by electrophoretically mediated microanalysis in a partially filled capillary

The screening of lipase inhibitors based on the metal-organic framework Zeolitic Imidazolate Framework-8-immobilized enzyme microreactor

An online capillary electrophoresis method based-lipase immobilized enzyme microreactor was developed for lipase kinetic study and inhibitor screening from compounds from natural products. Zeolitic Imidazolate Framework-8 (ZIF-8) has the advantages of large pore size, mild synthesis conditions and good biocompatibility. Lipase was immobilized on the inner wall of capillary with the help of the metal-organic framework ZIF-8. The results of electron microscopy showed that lipase could be aggregated and fixed on the inner wall of capillary by ZIF-8. After the experimental conditions including electrophoretic separation and enzymatic reaction were optimized, the baseline separation of substrate p-nitrophenyl acetate (pNPA) and product p-nitrophenol (pNP) was achieved within 3 min. The immobilized enzyme microreactor showed good repeatability and stability, and the determined Michaelis-Menten constant (Km) of lipase was 2.75 mM, which was lower than the kinetic constant determined in off-line reaction, indicating that the immobilized enzyme had a high affinity with the substrate. In addition, the IC50 value of the positive control compound orlistat on lipase inhibition was 7.26 nM, which was consistent with the literature. Then the inhibitory activity of 10 compounds from natural products on lipase was evaluated by the ZIF-8-IMER. Among them, 7 compounds including baicalein, luteolin, epicatechin gallic acid, and chlorogenic acid, had a certain inhibitory effect on lipase. The molecular docking technology proved the interaction between the enzyme and the screened inhibitor, which provides a new method for the screening of lipase inhibitors.

Prediction of the mechanisms of action of Zhibai Dihaung Granule in cisplatin-induced acute kidney injury: A network pharmacology study and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Zhibai Dihuang Granule (ZDG) is known as traditional Chinese patent medicine with the functions of "Ziyin decrease internal heat" in Traditional Chinses medicine. In clinical, it is also used to treat various kidney diseases.

AIM OF THE STUDY

We aimed to provide a basis for the curative effect of ZDG on acute kidney injury induced by cisplatin (CIAKI).

MATERIALS AND METHODS

The active compounds and protein targets of ZDG, as well as the potential targets of the CIAKI were searched from the database. The protein-protein interaction (PPI) network diagram and the drug-compounds-targets-disease network were constructed. Enrichment analysis was performed by Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG). Subsequently, the effect of ZDG on the prevention and treatment of CIAKI was experimentally validated in vivo and in vitro.

RESULTS

From the database, we screened 22 active compounds of ZDG and 226 related targets. We obtained 498 gene targets related to CIAKI, among which 40 genes overlapped with ZDG-related targets. Go enrichment and KEGG analysis got 339 terms and 64 pathways, respectively. Based on the above study, we speculated that ZDG has the potential effect on treatment CIAKI, and the mechanism may be related to cell apoptosis and inflammation. The results in vitro experiments showed that ZDG reduced the cytotoxicity of cisplatin to HK-2 and 293T cells, but did not affect the antitumor effect of cisplatin. Moreover, in vivo experiments further proved that ZDG effectively controlled kidney damage caused by cisplatin in SD rats. The results showed that ZDG could regulate the expression of CASP3, p65 and MAPK pathway related proteins, suggesting that ZDG's prevention of CIAKI may be related to apoptosis and inflammatory response.

CONCLUSIONS

Our study showed that ZDG could prevent and treat CIAKI by inhibiting cell apoptosis and inflammation, which provided a new efficacy and clinical application for ZDG.

The Role of Aromatase Enzyme in Hormone Related Diseases and Plant-Based Aromatase Inhibitors as Therapeutic Regimens

Medicinal plants have a long history of use as food and remedy in traditional and modern societies, as well as have been used as herbal drugs and sources of novel bioactive compounds. They provide a wide array of chemical compounds, many of which can not be synthesized via current synthesis methods. Natural products may provide aromatase inhibitory activity through various pathways and may act clinically effective for treating pathologies associated with excessive aromatase secretion including breast, ovarian and endometrial cancers, endometriosis, uterine fibroid, benign prostatic hyperplasia (BPH), prostate cancer, infertility, and gynecomastia. Recent studies have shown that natural products with aromatase inhibitory activity, could also be good options against secondary recurrence of breast cancer by exhibiting chemopreventive effects. Therefore, screening for new plant-based aromatase inhibitors may provide novel leads for drug discovery and development, particularly with increased clinical efficacy and decreased side effects.

Screening carbonic anhydrase IX inhibitors in traditional Chinese medicine based on electrophoretically mediated microanalysis

An electrophoretically mediated microanalysis (EMMA) method for the screening of carbonic anhydrase IX inhibitors in traditional Chinese medicine (TCM) was developed. This method combines transverse diffusion of laminar flow profiles (TDLFP) and rapid polarity switching technology to achieve rapid mixing of different reactants. Different electromigration rates of different substances make it possible that incubation, separation and detection are carried out continuously in a same fused-silica capillary. In this experiment, p-nitrophenyl acetate (pNPA) was used as the substrate for the enzyme reaction, which solved the problem that capillary electrophoresis could not detect carbonate, carbon dioxide, etc., the conventional substrates of carbonic anhydrase IX. After optimizing the enzyme reaction and separation conditions, the separation of substrate and product can be finished by baseline within 4 min. The Michaelis constant of carbonic anhydrase IX was measured to be 1.2 mM. A known inhibitor acetazolamide was used to evaluate the feasibility of this method for screening carbonic anhydrase IX inhibitors, and the half-maximal inhibitory concentration (IC₅₀) was calculated to be 1.26 μM. Finally, 4 natural compounds of 15 traditional Chinese medicine standards were discovered to exhibit enzyme inhibitory activity, including polydatin, matrine, dauricine and cepharanthine, proving that the EMMA method is an effective means for screening carbonic anhydrase IX inhibitors. The results were supported by molecular docking study.

On-line screening of indoleamine 2,3-dioxygenase 1 inhibitors by partial filling capillary electrophoresis combined with rapid polarity switching

Indoleamine 2,3-dioxygenase 1 (IDO1) has been shown to play an important role in the immune escape process of tumors, and therefore is considered as a promising target for tumor immunotherapy. In this study, off-line and on-line capillary electrophoresis methods were developed for IDO1 inhibitors screening from natural product extracts. The optimized separation conditions of CE were achieved with 32 mM sodium tetraborate (pH 9.22) as background electrolyte, using a separation voltage of 21 kV. The off-line CE method was verified by the determination of enzymatic kinetic parameters and inhibitory mechanisms of two known inhibitors. A partial filling on-line CE method combined with rapid polarity switching was used for rapid screening of IDO1 inhibitors. The whole reaction and separation process was completed within 5 min. The on-line CE screening results showed that six of 18 natural products had inhibitory effect on IDO1, namely Carthamus tinctorius, Schisandra chinensis, Raisin, Coffee, Hawthorn and Radix angelicae sinensis. The results of on-line CE experiments were consistent with the off-line results, which proved the practicability and effectiveness of the method for inhibitors screening.

Development of a new nano arginase HPLC capillary column for the fast screening of arginase inhibitors and evaluation of their binding affinity

A simple and rapid Nano LC method has been developed for the screening of arginase inhibitors. The method is based on the immobilization of biotinylated arginase on a neutravidin functionalized nano HPLC capillary column. The arginase immobilization step performed by frontal analysis is very fast and only takes a few minutes. The miniaturized capillary column of 170 nL (length 5 cm, internal diameter 75 μm) significantly decreased the required amount of used enzyme (25 pmol). This was of significance importance when working with less available or expensive purified enzyme. Non-selective adsorption of the organic monolith matrix was reduced (<6%) and the arginase efficient yield was high (92%). The resultant affinity capillary columns showed excellent repeatability and long lifetime. The arginase reaction product was achieved within 60 s and the immobilized arginase retained 97% of the initial activity beyond 90 days. This novel approach can thus be used for the fast evaluation of recognition assay induced bya series of inhibitor molecules (caffeic acid phenylamide, chlorogenic acid, piceatannol, nor-NOHA acetate) and plant extracts.

Pharmacological Modulation of Steroid Activity in Hormone-Dependent Breast and Prostate Cancers: Effect of Some Plant Extract Derivatives

The great majority of breast and prostate tumors are hormone-dependent cancers; hence, estrogens and androgens can, respectively, drive their developments, making it possible to use pharmacological therapies in their hormone-dependent phases by targeting the levels of steroid or modulating their physiological activity through their respective nuclear receptors when the tumors relapse. Unfortunately, at some stage, both breast and prostate cancers become resistant to pharmacological treatments that aim to block their receptors, estrogen (ER) or androgen (AR) receptors, respectively. So far, antiestrogens and antiandrogens used in clinics have been designed based on their structural analogies with natural hormones, 17-β estradiol and dihydrotestosterone. Plants are a potential source of drug discovery and the development of new pharmacological compounds. The aim of this review article is to highlight the recent advances in the pharmacological modulation of androgen or estrogen levels, and their activity through their cognate nuclear receptors in prostate or breast cancer and the effects of some plants extracts.

Clinical and pharmaceutical applications of affinity ligands in capillary electrophoresis: A review

Affinity capillary electrophoresis (ACE) is a separation technique that combines a biologically-related binding agent with the separating power and efficiency of capillary electrophoresis. This review will examine several classes of binding agents that have been used in ACE and applications that have been described for the resulting methods in clinical or pharmaceutical analysis. Binding agents that will be considered are antibodies, aptamers, lectins, serum proteins, carbohydrates, and enzymes. This review will also describe the various formats in which each type of binding agent has been used in CE, including both homogeneous and heterogeneous methods. Specific areas of applications that will be considered are CE-based immunoassays, glycoprotein/glycan separations, chiral separations, and biointeraction studies. The general principles and formats of ACE for each of these applications will be examined, along with the potential advantages or limitations of these methods.

The Chinese herbal formula Zhibai Dihuang Granule treat Yin-deficiency-heat syndrome rats by regulating the immune responses

ETHNOPHARMACOLOGICAL RELEVANCE

Zhibai Dihuang Granule (ZDG), a traditional Chinese medicine (TCM) made from eight Chinese herbs, has been classically used to treat Yin-deficiency-heat (YDH) syndrome. ZDG is well known with the therapeutic efficacy of nourishing Yin and decreasing internal heat in clinic, but the mechanism of ZDG's therapeutic effect is still not clear.

MATERIALS AND METHODS

High doses of triiodothyronine (T3) were given intraperitoneally to induce Hyperthyroid YDH syndrome in SD rats. The animals were then treated with ZDG for one week. The iTRAQ-coupled with two-dimensional liquid chromatography-tandem mass spectrometry (2D LC-MS/MS) technique was used to screen the differentially expressed serum proteins between ZDG treated rats and YDH syndrome rats. The differentially expressed proteins were analyzed by bioinformatics method and were verified by enzyme-linked immunosorbent assay (ELISA).

RESULTS

A total of 55 differentially expressed proteins were identified, including 23 up-regulated proteins (>1.25 fold, p < 0.05) and 32 down-regulated proteins (<0.80 fold, p < 0.05). Among the differentially expressed proteins, 26 proteins returned to normal after ZDG treatment. Bioinformatics analysis showed that these proteins were mainly involved in immune response, including regulation of immune system process, complement activation, and humoral immune response mediated by circulating immunoglobulin. ELISA revealed significantly increased levels of Zinc-alpha-2-glycoprotein (Azgp1), L-selectin, C-reactive protein (Crp), Plasminogen (Plg), Kininogen 1 (Kng1), and significantly decreased levels of Mannose binding lectin 2 (Mbl2) and Complement C1qb chain (C1qb) in ZDG treated rats compared with YDH syndrome rats. Bioinformatics analyses indicated that Azgp1 participated in antigen processing and presentation, Crp, C1qb, and Mbl2 were involved in complement activation, while L-selectin, Plg, and Kng1 were involved in regulating the inflammatory response.

CONCLUSIONS

Our study provides experimental evidence to understand the therapeutic mechanism of ZDG in YDH syndrome. The results suggested that ZDG may regulate the complement activation and inflammatory response, and promote the ability to recognize antigens to alleviate YDH syndrome.

Advances in enzyme substrate analysis with capillary electrophoresis

Capillary electrophoresis provides a rapid, cost-effective platform for enzyme and substrate characterization. The high resolution achievable by capillary electrophoresis enables the analysis of substrates and products that are indistinguishable by spectroscopic techniques alone, while the small volume requirement enables analysis of enzymes or substrates in limited supply. Furthermore, the compatibility of capillary electrophoresis with various detectors makes it suitable for KM determinations ranging from nanomolar to millimolar concentrations. Capillary electrophoresis fundamentals are discussed with an emphasis on the separation mechanisms relevant to evaluate sets of substrate and product that are charged, neutral, and even chiral. The basic principles of Michaelis-Menten determinations are reviewed and the process of translating capillary electrophoresis electropherograms into a Michaelis-Menten curve is outlined. The conditions that must be optimized in order to couple off-line and on-line enzyme reactions with capillary electrophoresis separations, such as incubation time, buffer pH and ionic strength, and temperature, are examined to provide insight into how the techniques can be best utilized. The application of capillary electrophoresis to quantify enzyme inhibition, in the form of KI or IC50 is detailed. The concept and implementation of the immobilized enzyme reactor is described as a means to increase enzyme stability and reusability, as well as a powerful tool for screening enzyme substrates and inhibitors. Emerging techniques focused on applying capillary electrophoresis as a rapid assay to obtain structural identification or sequence information about a substrate and in-line digestions of peptides and proteins coupled to mass spectrometry analyses are highlighted.

Recent advances in screening of enzymes inhibitors based on capillary electrophoresis

Capillary electrophoresis with many advantages plays an important role in pharmaceutical analysis and drug screening. This review gives an overview on the recent advances in the developments and applications of capillary electrophoresis in the field of enzyme inhibitor screening. The period covers 2013 to 2017. Both the pre-capillary enzyme assays and in-capillary enzyme assays which include electrophoretically mediated microanalysis (EMMA) and immobilized enzyme microreactor (IMER) are summarized in this article.

Screening of tyrosinase inhibitors by capillary electrophoresis with immobilized enzyme microreactor and molecular docking

A new method for screening tyrosinase inhibitors from traditional Chinese medicines (TCMs) was successfully developed by capillary electrophoresis with reliable online immobilized enzyme microreactor (IMER). In addition, molecular docking study has been used for supporting inhibition interaction between enzyme and inhibitors. The IMER of tyrosinase was constructed at the outlet of the capillary by using glutaraldehyde as cross-linker. The parameters including enzyme reaction, separation of the substrate and product, and the performance of immobilized tyrosinase were investigated systematically. Because of using short-end injection procedure, the product and substrate were effectively separated within 2 min. The immobilized tyrosinase could remain 80% active for 30 days at 4°C. The Michaelis-Menten constant of tyrosinase was determined as 1.78 mM. Kojic acid, a known tyrosinase inhibitor, was used as a model compound for the validation of the inhibitors screening method. The half-maximal inhibitory concentration of kojic acid was 5.55 μM. The method was successfully applied for screening tyrosinase inhibitors from 15 compounds of TCM. Four compounds including quercetin, kaempferol, bavachinin, and bakuchiol were found having inhibitory potentials. The results obtained in this work were supported by molecular docking study.

Screening of neuraminidase inhibitors from traditional Chinese medicine by transverse diffusion mediated capillary microanalysis

A transverse diffusion mediated capillary microanalysis method has been developed for screening of neuraminidase inhibitors from traditional Chinese medicine. The enzyme, substrate and inhibitors were sequentially injected, mixed efficiently by transverse diffusion of laminar flow profiles, then incubated and separated in the same capillary. To enhance the mixing efficiency of reactants, running buffer was injected by alternately applying +5 kPa and -5 kPa at the capillary inlet and the procedure was repeated three times. The capillary electrophoresis (CE) separation conditions and reactants mixing conditions were optimized. Dual-wavelength detection was employed to eliminate the interference with natural compounds. The method has been applied to determine the kinetics constant of neuraminidase and screen 12 compounds from traditional Chinese medicine. Four compounds have been found to be positive for enzyme inhibition. The results are in good agreement with those reported in the literature. The method realized the mixing of substrate and enzyme with identical electrophoretic mobility. This novel CE method was simple, rapid, economic, and fully automated. Therefore, it was appropriate for neuraminidase inhibitors screening and could be extended to other high-throughput screening of active components from traditional Chinese medicine.

Recent advances in CE-mediated microanalysis for enzyme study

This review gives an overview of the recent developments and applications in the use of CE-mediated microanalysis for enzyme studies. The period covers mid-2011 until mid-2013. Both off-line and in-line enzyme assays with their applications using CE are described in this article. For the in-capillary enzyme reaction, the techniques using electrophoretically mediated microanalysis (EMMA) as well as immobilized enzyme reactor (IMER) are discussed. The applications include the evaluation of enzyme activity, enzyme kinetics, enzyme inhibition, screening of enzyme inhibitors, and the study of enzyme-mediated drug metabolism.