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In present study, a novel glutathione functionalized MoS 2 quantum dots (GSH-MoS 2 QDs) was synthesized from sodium molybdate dehydrate and glutathione by using a one-pot hydrothermal method. After they were characterized, the influence of GSH-MoS 2 QDs on amyloid aggregation of bovine serum albumin (BSA) was investigated by various analytical methods including thioflavin T fluorescence assay, circular dichroism and transmission electron microscope. Moreover, the effect of GSH-MoS 2 QDs on cytotoxicity induced by BSA amyloid fibrils and cell penetration were evaluated by MTT assay and confocal fluorescence imaging, respectively. The results indicated that the GSH-MoS 2 QDs not only had good water solubility, excellent biocompatibility and low cytotoxicity, but also could obviously inhibit the aggregation of BSA and depolymerize the formed BSA aggregates. The data obtained from this work demonstrated that the GSH-MoS 2 QDs is expected to become a candidate drug for the treatment of amyloid-related diseases. • A novel GSH-MoS 2 QDs was synthesized by one-pot hydrothermal approach. • The as-prepared QDs can inhibit BSA aggregation and depolymerize BSA fibrils. • The QDs exhibits good biocompatibility, low cytotoxicity and cell permeability. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel 4-MPBA-MoS 2 QDs was synthesized by one-pot hydrothermal approach. • The prepared QDs have a uniform spherical appearance with a diameter of 1.5 ∼ 3.0 nm. • Inhibitory effects of the QDs on BSA amyloid aggregation were investigated. • Molecular docking reveals the mechanism of QDs inhibiting BSA amyloid aggregation. In recent years, seeking and screening of compounds that can inhibit and/or depolymerize protein aggregation has been a hot issue in the field of pharmaceutical research. As a new material, quantum dots have been widely concerned by medical researchers. In present study, a novel 4-mercaptophenylboronic acid functionalized MoS 2 quantum dots (4-MPBA-MoS 2 QDs) was successfully synthesized through a one-pot hydrothermal approach by using molybdate dehydrate and 4-mercaptophenylboronic acid as Mo and S source, respectively. Transmission electron microscopy observation showed that the morphology and microstructure of the 4-MPBA-MoS 2 QDs displayed uniform spherical shape with a diameter of approximately 1.5 ∼ 3.0 nm. The UV and fluorescence spectra experiments indicated that the prepared QDs had good water solubility and two weak absorption peaks were appeared at 280 nm and 310 nm. When the excitation wavelength was set to 310 nm, the 4-MPBA-MoS 2 QDs had the strongest fluorescence intensity, and the maximum emission wavelength appeared at 405 nm. In vitro experiments showed that the 4-MPBA-MoS 2 QDs could significantly reduce the aggregation of bovine serum albumin (BSA). Especially when the mass ratio of BSA to 4-MPBA-MoS 2 QDs was 1:5, the inhibition rate could reach 76.4%. Cell experiment showed that the presence of 4-MPBA-MoS 2 QDs could obviously decrease the cytotoxicity induced by BSA amyloid fibrils. Moreover, the depolymerization of BSA amyloid fibrils by 4-MPBA-MoS 2 QDs and its excellent cell permeability were also observed. Molecular docking studies have shown that 4-MPBA-MoS 2 QDs may stabilize the BSA structure through van der Waals forces, hydrophobic force, electrostatic interactions and hydrogen bonds formed between the outer layer of 4-MPBA and BSA to prevent fibrosis aggregation. The results of this study suggested that 4-MPBA-MoS 2 QDs showed low cytotoxicity, good biocompatibility and solubility, and had a great potential in the design of new drugs for the treatment of amyloid-related diseases. [ABSTRACT FROM AUTHOR]

In this study, the inhibitory effects of four anthraquinones including chrysophanol, emodin, physcione and rhein on tyrosinase were investigated by enzyme inhibition assay. The results indicated that all of anthraquinones could significantly inhibit the activity of tyrosinase in a competitive manner. To gain insight into the inhibitory mechanism of anthraquinones on tyrosinase, spectroscopic analysis combined with molecular docking studies were performed. Fluorescence results showed that anthraquinones interacted with tyrosinase by static quenching in a molecular ratio of 1:1. Circular dichroism and molecular docking suggested that anthraquinones could not chelate directly the copper ions but they could bind to amino acid residues in the active site of tyrosinase via electrostatic forces and hydrophobic interactions, as well as hydrogen bonds, and the binding processes resulted in the conformational changes of tyrosinase and prevented the substrate (L -DOPA) from entering the active site, which led to the decrease of tyrosinase activity. Our study in this paper provides a scientific basis for revealing the inhibition of tyrosinase activity by anthraquinone compounds. As a natural inhibitor of tyrosinase, anthraquinones can be used as a potential agent to reduce enzymatic browning reactions, such as food browning and melanization of skin. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the inhibitory kinetics of aloe-emodin on the activity of tyrosinase and the inhibitory mechanism have been investigated by using spectroscopic and molecular docking techniques. The results showed that aloe-emodin inhibited tyrosinase activity in a competitive manner. The binding constants, number of binding sites and thermodynamic parameters obtained at different temperature suggested that aloe-emodin spontaneously binds to tyrosinase at one binding site, mainly via electrostatic forces. Analysis by UV–vis absorption (UV), circular dichroism (CD) and molecular docking indicated that aloe-emodin bound directly into the catalytic cavity and that binding of aloe-emodin to tyrosinase induced conformational changes of the enzyme and blocked the catalytic center of the enzyme preventing binding of the substrate, which caused the inhibition of the tyrosinase activity. Graphical Abstract Unlabelled Image Highlights • The inhibitory effects of aloe-emodin on tyrosinase were measured in vitro. • Binding mechanisms were investigated by spectroscopic and docking methods. • The interaction of tyrosinase with aloe-emodin occurred in the hydrophobic cavity. • The common residues lining the aloe-emodin in the catalytic site were investigated. [ABSTRACT FROM AUTHOR]

Abstract In this study, a novel glycoprotein with molecular weight of 22.0 kDa was isolated and purified from Fupenzi (a kind of unripe fruits of Rubus chingii Hu.) by means of anion-exchange (DEAE-52) and gel column chromatography (Sephadex G-100). The glycoprotein consists of a carbohydrate component (81.42 ± 0.96%) and protein component (14.56 ± 1.21%). The anti-aging capability was measured in d ‑galactose induced aging mice model, and the experimental data showed that the glycoprotein could significantly inhibit the formation of malondialdehyde (MDA) and raise the activities of superoxide dismutase (SOD) and catalase (CAT) in mice kidney and serum. The reverse transcription polymerase chain reaction (RT-PCR), quantitative real time polymerase chain reaction (Q-PCR) and western blots showed that the glycoprotein significantly increase the expression of anti-aging gene klotho in mice kidney. The results suggested that the anti-aging mechanism of FPZ might be achieved by improving the klotho gene expression and repairing the renal function. This study will provide a scientific basis for the view of traditional Chinese medicine that tonifying kidney is the basic way of anti-aging. In addition, the glycoprotein could be exploited as a potent dietary supplement to attenuate aging and prevent age-related diseases in humans. [ABSTRACT FROM AUTHOR]

In this study, the fibrillation of hen egg-white lysozyme (HEWL) in the absence and presence of different amount of nitrogen-doped graphene quantum dots (N-GQDs) was studied by Thioflavin T (ThT) spectroscopy, Congo red (CR) binding assays, 8-anilino-1-naphthalenesulfonic acid (ANS) fluorescence assay, circular dichroism (CD) and transmission electron microscopy (TEM). The experimental results indicated that not only the fibrillation of HEWL at high temperature (65 °C) and low pH (pH = 2.0) could be inhibited effectively by N-GQDs, but the inhibition of HEWL by N-GQDs followed a dose-dependent manner. The results of this work suggested that the N-GQDs had a great potential for designing new therapeutic agents and were promising for future treatment of amyloid-related diseases. [ABSTRACT FROM AUTHOR]

In this work, the inhibitory effect of two isoflavonoids including daidzein and genistein on trypsin and their binding mechanism were determined by spectroscopic and molecular docking approaches. The results indicated that both daidzein and genistein reversibly inhibited trypsin in a competitive manner with IC 50 values of 68.01 × 10 −6 mol L −1 and 64.70 × 10 −6 mol L −1 and K i values of 62.12 × 10 −6 mol L −1 and 59.83 × 10 −6 mol L −1 , respectively. They could spontaneously bind with trypsin mainly through hydrophobic force and electrostatic interactions with a single binding site. Analysis of circular dichrosim spectra and molecular docking revealed that both isoflavonoids bound directly into the catalytic cavity and the microenvironment and secondary structure of trypsin were changed in this process, which caused the inhibition of trypsin activity. All these experimental results and theoretical data in this work would be help in understanding the mechanism of inhibitory effects of daidzein and genistein against trypsin and the potential of isoflavonoid to relieve symptoms of pancreatitis. [ABSTRACT FROM AUTHOR]

In the work described on this paper, the inhibitory effect of 10 flavonoids on pepsin and the interactions between them were investigated by a combination of spectroscopic and molecular docking methods. The results indicated that all flavonoids could bind with pepsin to form flavonoid–pepsin complexes. The binding parameters obtained from the data at different temperatures revealed that flavonoids could spontaneously interact with pepsin mainly through electrostatic forces and hydrophobic interactions with one binding site. According to synchronous and three-dimensional fluorescence spectra and molecular docking results, all flavonoids bound directly into the enzyme cavity site and the binding influenced the microenvironment and conformation of the pepsin activity site which resulted in the reduced enzyme activity. The present study provides direct evidence at a molecular level to understand the mechanism of digestion caused by flavonoids. [ABSTRACT FROM AUTHOR]

In the work described on this paper, the bindings of baicalein and chrysin with hyaluronidase (HAase) were studied by fluorescence, synchronous fluorescence, three-dimensional fluorescence and molecular docking methods. The results indicated that both of flavones could interact with HAase to form flavone–HAase complexes. The binding constant, number of binding sites and thermodynamic parameters were measured at different temperature, which indicated that flavones could spontaneously bind with HAase through electrostatic forces with one binding site. Based on synchronous and three-dimensional fluorescence spectra and the molecular docking results, both of flavones bound directly into the enzyme cavity site and the binding of flavones into the enzyme cavity influenced the microenvironment of the HAase activity site which resulted in the reduced HAase activity. The present study provides direct evidence at a molecular level to understand the mechanism of inhibitory effect of flavone against HAase and explain the anti-inflammatory mechanism of Scutellaria baicalensis Georgi as an anti-inflammatory drug. [ABSTRACT FROM AUTHOR]

Highlights: [•] The interaction between silybin and pepsin was investigated by spectral and docking methods. [•] The hydrophobic interaction was the main mode for stabilizing the silybin-pepsin complex. [•] Synchronous and three-dimensional fluorescence spectra of silybin-pepsin were showed in paper. [•] The interaction of pepsin with silybin occurred in the hydrophobic cavity of pepsin. [•] The effect of silybin on pepsin activity was first investigated in rats. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a high performance liquid chromatography (HPLC) coupled with diode array detection (DAD) for simultaneous determination of six flavones including baicalein, sophoricoside, rutin, baicalin, quercetin and genistein in rat plasma and tissues after oral administration of JiangYaBifeng (JYBF) tablets was developed. The investigated analytes in plasma and tissues were extracted and purified with liquid–liquid extraction and solid phase extraction (SPE). Chromatographic separation was accomplished on a DIONEX Acclaim C18 column (250mm×4.6mm, 5.0μm particle size) with a simple linear gradient elution. The calibration curves for all the flavones had good linearity in the measured range with R 2 higher than 0.9983. The relative errors (REs) of the intra- and inter-day accuracy at different flavones levels were all less than ±10%. The proposed method enables unambiguous identification and quantification of investigated flavones in vivo. This is the first report on determination of the major flavones in rat plasma and tissues after oral administration of JYBF tablets. The results provided a meaningful basis for evaluating the clinical application of this medicine. [Copyright &y& Elsevier]

Abstract: In this paper, based upon the phenomenon that melamine can obviously enhance the CL signal of the luminol–H2O2 system in basic medium, a simple, rapid and sensitive flow injection chemiluminescence (FI-CL) method for the determination of melamine has been developed. Under the optimum conditions, the linear range for the determination of melamine was 0.2–80μgmL−1 with a detection limit of 0.12μgmL−1 calculated as proposed by IUPAC and a relative standard deviation of 3.26% for 11 solutions of 10μgmL−1 melamine on the same day. The proposed method was satisfactorily applied to determine melamine in milk-based products and satisfactory results were obtained without interferences from the sample matrix. Moreover, one assay produce takes only 25s and the minimum sampling rate is about 120 samplesh−1, which indicated that the FI-CL method was suitable for high throughput and real-time melamine analysis. [Copyright &y& Elsevier]

Abstract: An effective, accurate and reliable method was developed for the simultaneous separation and determination of eight active components (baicalin, baicalein, sophoricoside, rutin, quercetin, genistein, pargyline and hydrochlorothiazide) in Chinese medicine ‘JiangYaBiFeng’ tablet (JYBF tablet) by high-performance liquid chromatography (HPLC) coupled with diode array detection (DAD). Due to the different UV characteristic of these components, different wavelengths were selected for analysis of different analytes, such as 210nm for pargyline, 256nm for sophoricoside, rutin, quercetin and genistein, and 280nm for baicalin, baicalein and hydrochlorothiazide. Excellent linear behaviors over the investigated concentration ranges were observed with the values of R 2 higher than 0.9990 for all analytes. The recovery rates and relative standard deviation (RSD) for all analytes at three different concentrations were 94.9–104.7% and 1.23–3.00%, respectively. The validated method was successfully applied to the simultaneously determination of these active components in ‘JiangYaBiFeng’ tablet from different production batches, indicating that the proposed method in this paper was particularly suitable for the routine analysis of JYBF tablet and its quality control. [Copyright &y& Elsevier]

Abstract: In the work described on this paper, a highly specific and sensitive enzyme-linked immunosorbent assay (ELISA) for the determination of glycyrrhizin (GL) was developed. To demonstrate the potential of the ELISA, a preliminary pharmacokinetic study of GL in rats and quantitative analysis of GL in several Chinese prescriptions were performed and compared with high-performance liquid chromatography (HPLC). The experimental data indicated that ELISA method exhibits more advantages over HPLC, such as lower detection limit, high specificity, low background and no requirement of sample pre-treatment, and more suitable for the determination of natural components in Chinese traditional medicines. [Copyright &y& Elsevier]

The binding mode between tyrosinase and resveratrol/oxyresveratrol. (a) Overlapping map of the binging site with the lowest binding energy between tyrosinase and resveratrol/oxyresveratrol; (b) the binding of kojic acid with the amino acid residues in the active site; (c) the binding of resveratrol with the amino acid residues in the active site; (d) the binding of oxyresveratrol with the amino acid residues in the active site. The purple carets show the amino acid residues which involved in hydrogen bonding and electrostatic interaction, while the green carets indicate the amino acid residues which involved in van der Waals interaction. The broken display hydrogen bond and the direction of the arrow is from the donor to the acceptor. • The inhibitory effects of resveratrol/oxyresveratrol on tyrosinase were investigated. • The differences of inhibitory mechanism of them were revealed. • The inhibition mechanism was further verified by molecular docking. Resveratrol and oxyresveratrol are two natural polyhydroxy trans -stilbene products. Previous studies have shown that both of them can effectively inhibit the activity of tyrosinase. However, little attention has been paid to study the difference of their inhibitory mechanism. To reveal this difference, in this work a comparative study on the inhibitory effects of resveratrol and oxyresveratrol against cellular tyrosinase activity and melanin content were investigated by B16F0 cells, and the inhibitory mechanism of them on tyrosinase was revealed by cell-free tyrosinase inhibition, intrinsic fluorescence spectrum, circular dichroism and molecular docking. The results showed that the inhibitory capacity of oxyresveratrol toward tyrosinase activity and melanin formation was better than that of resveratrol. The difference of their inhibitory mechanism may be closely related to the different types of inhibition, the different strength of their interaction with tyrosinase and the different number of hydrogen bonds between them. The data in this study provide a scientific basis for revealing the inhibitory mechanisms of resveratrol and oxyresveratrol toward tyrosinase, and lay an experimental foundation for further development and utilization of them. [ABSTRACT FROM AUTHOR]

Abstract In this study, cysteamine-functionalized molybdenum disulfide quantum dots (MoS 2 QDs) were synthesized by a one-pot hydrothermal method. A range of techniques including of Thioflavin T and 8-Anilino-1-naphthalenesulfonic acid fluorescence assays, circular dichroism, and transmission electron microscope have been employed to determination the efficacy of MoS 2 QDs on the inhibition/reversion of fibrillation and hindering cytotoxicity induced by protofibrils and amyloid fibrils of bovine serum albumin (BSA). Results demonstrated that MoS 2 QDs could effectively inhibit the fibrillogenesis and destabilize preformed fibrils of BSA in a concentration-dependent manner. Cytotoxicity protection and imagine on Hela cells was investigated using the methyl thiazolyl tetrazolium (MTT) assay. It was found that MoS 2 QDs not only has good biocompatibility, low toxicity and good cell penetration, but also could effectively decrease the cytotoxicity caused by the formed fibrils of BSA. The results obtained in this work suggested the potential biological application of MoS 2 QDs in therapeutics and provided new insight into the design of multifunctional nanomaterials for amyloid-related diseases. [ABSTRACT FROM AUTHOR]

[Display omitted] Resveratrol is a natural polyhydroxy trans-stilbene product with many biological activities. One of the most striking biological activities of it is its anti-aging potential. Resveratrol can exhibit anti-aging activity via a variety of signaling pathways, however, the repair effect of it on kidney and brain injury in aging mice induced by d -galactose and its regulation on klotho gene expression have not been reported. Herein, the anti-aging activity of resveratrol and its effect on the repair of kidney and brain injuries in d -galactose-induced aging mice, as well as its regulation of klotho gene expression in these two tissues were investigated. The results indicated that resveratrol could significantly increase the aged cell viability and improve the pathological status of aging mice via inhibiting the formation of malondialdehyde and enhancing the activities of superoxide dismutase and catalase. The histological analysis suggested that resveratrol could remarkably repair the damages of kidney and brain tissues in aging mice. Moreover, PCR and western blot have shown that resveratrol could obviously increase the anti-aging klotho gene expression in the above tissues. The data in this paper further revealed and enriched the anti-aging mechanism of resveratrol, and the methods established in this study can be used as a tool to evaluate the anti-aging activity of drugs to a certain extent. [ABSTRACT FROM AUTHOR]

In this study, the effect of a glycoprotein obtained from Fupenzi (FPZ) (Rubus chingii Hu.) on the fibrillation of bovine serum album (BSA) was investigated by multi-spectroscopic methods and transmission electron microscopy. Moreover, the cytotoxicity of the glycoprotein and the effect of it on H 2 O 2 -induced cell viability were investigated by cell counting kit and β-galactosidase kit, respectively. The experimental results indicated that the glycoprotein showed very low toxicity to NRK-52E cells and could obviously delay cell senescence and improve cell viability. Moreover, the glycoprotein could effectively inhibit the formation of BSA fibrils and destroy the stability of preformed BSA fibrils in a concentration-dependent manner. Generally, antioxidant capacities are thought to be related to the anti-amyloidogenic activity of inhibitors; therefore, to reveal the inhibitory mechanism, the anti-oxidative property of the glycoprotein was examined by DPPH and ABTS assays. The results demonstrated that FPZ glycoprotein had a remarkable antioxidant activity and the IC 50 values of DPPH and ABTS were 0.249 mg mL−1 and 0.092 mg mL−1, respectively. This work suggested that the FPZ glycoprotein had the potential to be designed a new therapeutic agent for attenuating aging and preventing the age-related diseases. Transmission electron microscopy images of BSA fibril. A: a flat-ribbon and long-rod-shaped, self-assembled network fibrils were appeared after the native BSA solution was incubated at 65 °C for 8 h. B: under the same experimental conditions, the amounts of fibrils were obviously reduced in the presence of 1.0 mg mL−1 glycoprotein. Unlabelled Image • Effect of a novel FPZ glycoprotein on fibrillation of BSA was investigated. • Toxicity of glycoprotein and its effect on H 2 O 2 -induced cell viability were tested. • Anti-oxidative property of glycoprotein was examined by DPPH and ABTS assays. [ABSTRACT FROM AUTHOR]

In this study, Chinese yam polysaccharides (CYP) were extracted from the tuber of Dioscorea opposita Thunb. by hot-water extraction and ethanol precipitation. After deproteinized by the Sevag method, the content of CYP was determined to be 91.77%. The anti-aging activities of the CYP were evaluated in aging mice induced by d -galactose in vitro and in vivo. The results indicated that the CYP not only could enhance the learning ability of mice, but alleviate the spatial memory impairment of mice. Furthermore, the CYP could effectively inhibit the formation of malondialdehyde and enhance the activities of superoxide dismutase, catalase and glutathione peroxidase in brain, liver and kidney tissues of mice. The histological analysis indicated that CYP could significantly alleviate the damages induced by d -galactose in the above tissues. Gene expression studies showed that the CYP could up-regulate the expression of anti-aging klotho gene in brain and kidney. Therefore, it can be concluded that the anti-aging effect of Chinese yam may be achieved by repairing the function of organs and improving the expression of klotho gene in mice. • The anti-aging activity of Chinese yam polysaccharides (CYP) was evaluated. • The CYP regulation on klotho gene expression was first investigated in mice. • The results in this work revealed the anti-aging mechanism of Chinese yam. [ABSTRACT FROM AUTHOR]