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[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]

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]

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]

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]

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]