Molecular dynamics simulation of the ligand binding domain of mGluR1 in response to agonist and antagonist binding

The interdomain movements of the ligand binding domain (LBD) of mGluR1 in response to agonist or antagonist binding are studied by 2 ns molecular dynamics (MD) simulations. Our results indicate that MD is able to reproduce many of the experimentally determined features of the open and closed conformations of LBD. Analysis of the ligand behavior over time allows to delineate some of the molecular determinants responsible for the agonist-induced or antagonist-blocked LBD responses.     

Isoform-selective modulators for metabotropic glutamate receptors and protein kinase C:Synthesis and biological evaluation

The synthetic studies for some known modulators of metabotropic glutamate receptors (mGluRs) such as (S)-αM4CPG,(1S,3fi)-ACPD,L-CCG-I are described.Based on the structure of αM4CPG several new conformationally constrained analogues are design ed and synthesized.Among them APICA is a selective antagonist for group II mGluRs.Also,a new benzolactam-V8 analogue is found to have better isoform-selectivity for protein kinase C family.Three different protocols for synthesizing benzolactam-V8 analogues are developed to meet the requirement for delivering more analogues to test.     

Positive allosteric modulators of type 5 metabotropic glutamate receptors (mGluR5) and their therapeutic potential for the treatment of CNS disorders

Studies utilizing selective pharmacological antagonists or targeted gene deletion have demonstrated that type 5 metabotropic glutamate receptors (mGluR5) are critical mediators and potential therapeutic targets for the treatment of numerous disorders of the central nervous system (CNS), including depression, anxiety, drug addiction, chronic pain, Fragile X syndrome, Parkinson's disease, and gastroesophageal reflux disease. However, in recent years, the development of positive allosteric modulators (PAMs) of the mGluR5 receptor have revealed that allosteric activation of this receptor may also be of potential therapeutic benefit for the treatment of other CNS disorders, including schizophrenia, cognitive deficits associated with chronic drug use, and deficits in extinction learning. Here we summarize the discovery and characterization of various mGluR5 PAMs, with an emphasis on those that are systemically active. We will also review animal studies showing that these molecules have potential efficacy as novel antipsychotic agents. Finally, we will summarize findings that suggest that mGluR5 PAMs have pro-cognitive effects such as the ability to enhance synaptic plasticity, improve performance in various learning and memory tasks, including extinction of drug-seeking behavior, and reverse cognitive deficits produced by chronic drug use.     

In silico rationalization of the structural and physicochemical requirements for photobiological activity in angelicine derivatives and their heteroanalogues

In PUVA (Psoralen plus UVA) chemotherapy 8-methoxypsoralen is the most widely used compound, although its efficacy is endowed with undesired side effects. In order to have an evident anti-proliferative activity with a reduced phototoxicity, many linear and angular derivatives have been synthesised. In this paper we describe a QSAR study in which, by means of the neural networks methodology, a useful model for predicting biological activity, expressed as ID₅₀ (the UVA dose that reduces to 50% the DNA synthesis in Ehrlich cells), has been derived. A decision tree that is able to discriminate between active and inactive compounds has been built based on recursive partitioning. The study shows the key structural features responsible for the activity and could be a helpful tool in the rational design of new, less toxic, photochemotherapeuthic agents.     

钨、钼、镍含量的改变对体相催化剂物化性质、加氢活性影响

制备不同活性金属原子比的体相催化剂,通过BET、XRD、SEM、TEM、强度测定、堆积密度测定及小型活性评价手段,考察了活性金属钨、钼、镍含量的变化对体相催化剂物化性质和活性的影响。结果表明,保持W/Mo原子比不变,随着(W+Mo)/Ni的原子比减小,孔体积、比表面积、孔径增大,超深度加氢脱硫活性增强,在精制油硫含量小于10μg/g,反应温度降低8℃。在(W+Mo)/Ni的原子比不变的条件下,W/Mo的原子比在0.28-1.85,随着原子比增大,孔体积、比表面积、超深度加氢脱硫活性没有明显变化。     

Prediction of physicochemical properties of organic molecules using van der Waals surface electrostatic potentials

The generalized interaction properties function (GIPF) methodology developed by Politzer and coworkers, which calculated molecular surface electrostatic potential (MSESP) on a density envelope surface, was modified by calculating the MSESP on a much simpler van der Waals (vdW) surface of a molecule. In this work, vdW molecular surfaces were obtained from the fully optimized structures confirmed by frequency calculations at B3LYP/6-31G(d) level of theory. Multiple linear regressions for normal boiling point, heats of vaporization, heats of sublimation, heats of fusion, liquid density, and solid density were performed using GIPF variables from vdW model surface. Results from our model are compared with those from Politzer and coworkers. The surface-dependent beta (and gamma) values are dependent on the surface models but the surface-independent alpha and regression coefficients (r) are constant when vdW surface and density surface with 0.001 a.u. contour value are compared. This interesting phenomenon is explained by linear dependencies of GIPF variables.     

Alteration of the physicochemical properties of catalysts based on aqueous solutions of Mo-V-P heteropoly acids in redox processes

Selective catalytic oxidation of various organic substrates with O₂ in the presence of aqueous solutions of Mo-V-P heteropoly acids (HPA) is carried out via two stages in separate reactors. In stage (1), a substrate is oxidized into a desired product while HPA is reduced. The reduced form of HPA is oxidized with O₂ in stage (2). A set of the physicochemical properties of the homogeneous catalyst has been found to alter continuously during these redox processes. Using a solution of the modified high-vanadium HPA (H₁₂P₃Mo₁₈V₇O₈₅), we demonstrate that the density, viscosity, and pH of this solution reach their maxima after reaction (1) and attain their minima after reaction (2). On the contrary, the redox potential of the solution is minimum after reaction (1), and maximum after reaction (2). All alterations of the physicochemical properties of the catalyst are found to be completely reversible.     

On some novel extended topochemical atom (ETA) parameters for effective encoding of chemical information and modelling of fundamental physicochemical properties

Extended topochemical atom (ETA) indices developed by our group have been extensively applied in our previous reports for toxicity and ecotoxicity modelling in the field of quantitative structure–activity relationships (QSARs). In the present study these indices have been further explored by defining additional novel parameters to model n-octanol–water partition coefficient (two data sets; n?=?168 and 139), water solubility (n?=?193), molar refractivity (n?=?166), and aromatic substituent constants π, MR, σ _m, and σ _p (n?=?99). All the models developed in the present study have undergone rigorous internal and external validation tests and the models have high statistical significance and prediction potential. In terms of Q ² and r ² values the models developed for the datasets of whole molecules are better than those previously reported, with topochemically arrived unique (TAU) indices on the same datasets of chemicals. An attempt has also been made to develop models using non-ETA topological and information indices. Interestingly, ETA and non-ETA models have been found to have similar predictive capacity.     

Green synthesis of Zn nanoparticles and in situ hybridized with BSA nanoparticles for Baicalein targeted delivery mediated with glutamate receptors to U87-MG cancer cell lines

Glioblastoma multiforme (GBM) is the most aggressive malignant tumor of the brain. It has different glutamate receptor types. So, these receptors can be a suitable target for GBM treatment. The current study investigated the anticancer effects of bovine serum albumin (BSA)-Baicalein @Zn-Glu nanostructure mediated-GluRs in human glioblastoma U87 cells. BSA-Ba@Zn-Glu hybrid nanoparticles (NPs) were set and considered transporters for Baicalein (Ba) active compound delivery. BSA-Ba@Zn-Glu NPs were synthesized by a single-step reduction process. The successful production was confirmed through transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), and hemolysis test. The cytotoxic efficacy and apoptosis rate of the nanostructures on U87 glioblastoma cells were investigated by 3-(4,5-dimethylthialzol-a-yl)-2,5 diphenyltetrazolium bromide (MTT) and flow cytometry assays, respectively. The synthesized BSA-Ba@Zn-Glu nanostructures with a diameter of 142.40 ± 1.91 to 177.10 ± 1.87 nm and zeta potential of −10.57 ± 0.71 to −35.77 ± 0.60 mV are suitable for extravasation into tumor cells. The drug release from the BSA-Ba@Zn NPs showed controlled and pH-dependent behavior. In vitro results indicated that the BSA-Ba@Zn-Glu NPs significantly reduce cell viability and promote apoptosis of U87 cancer cells. It revealed the cytotoxic effect of the Baicalein and an increase in cellular uptake of nanoparticles by Glu receptors. Zn NPs were synthesized based on a green synthesis method. BSA NPs were used as a nano-platform for Glu conjugation and Ba drug delivery. BSA-Ba@Zn-Glu NPs induce cytotoxicity and apoptosis in human brain cancer cells (U87) in a dose-dependent manner. Finally, this nanostructure could be served in targeted drug delivery in vivo studies and applied along with other strategies such as X-ray irradiation as combinational therapies in future studies.     

The influence of main emulsion components on the physicochemical properties of soursop beverage emulsions: A mixture design approach

The physicochemical properties of soursop beverage emulsion were investigated using mixture design. Results indicated that the regression models were significantly fitted for all response variables studied, except creaming index at 10°C. Interactions between biopolymers and oil phase had the most significant effect on creaming stability; however, modified starch played a much prominent role in maintaining the cloudiness and average droplet size. Meanwhile, WPI contributed significantly to the conductivity of the emulsions. The optimum condition resulted in desirable physicochemical properties could be achieved using 8.70% (w/w) modified starch, 1.02% (w/w) WPI, 10.11% (w/w) flavor oil, and 76.57% (w/w) water.     

General synthetic methods for the preparation of pinwheel receptors

The synthesis of bis-trityl diynes, used as cooperative fluorescent chemosensors, is described. The most convenient sequence for the preparation of the sensor framework was found to be intolerant of most functionality. Therefore, an unfunctionalized framework is constructed and recognition elements are selectively installed via electrophilic substitution on an electronically differentiated key intermediate. A divergent synthesis of a general class of chemical sensors emerges. This synthetic method is highlighted by its simplicity and modularity allowing for the introduction of various recognition elements and fluorophores.     

ONIOM and FMO‐EDA study of metabotropic glutamate receptor 1: Quantum insights into the allosteric binding site

The crystal structure of metabotropic glutamate receptor 1 (mGluR1) complexed with 4‐fluoro‐N‐(4‐(6‐(isopropylamino)pyrimidin‐4‐yl)thiazol‐2‐yl)‐N‐methylbenzamide (FITM, a negative allosteric modulator) and its twelve close structural analogs with a broad spectrum of affinities (2.4 nM < IC₅₀ > 10 000 nM) were investigated using quantum mechanical methods. The our own N‐layered integrated molecular orbital and molecular mechanics (ONIOM) was used to optimize the molecular geometries of the receptor with complexed ligands, which were then used to perform the ab initio calculations using the fragment molecular orbitals method with energy decomposition analysis (FMO‐EDA). The results clearly showed that residues Q660^3.28 and/or Y805^6.55 were the anchoring points for all the studied analogs of FITM, while the H‐bond with T815^7.38 determined only the orientation of very active molecules containing an amino substituent in the pyrimidine moiety (e.g., FITM). The orientation of the other parts of ligands resulted from hydrophobic interactions mainly with L757^5.44, F801^6.51, or W798^6.48. The applied ONIOM/FMO–EDA approach facilitated the study of effects related to very small changes in the ligand structure and led to conclusions regarding the significance of individual interactions in the allosteric binding pocket of mGluR1.     

Flexible but with a defined turn-influence of the template on the binding properties of two-armed receptors

Combinatorial binding studies revealed that the di(trans-4-aminoproline)diketopiperazine is an ideal template for two-armed receptors with highly selective binding properties towards peptides. It is not only superior to structurally very different diamines but also to the diastereomeric di(cis-4-aminoproline)diketopiperazine. These empiric results are rationalized by the analysis of the conformation of the diastereomeric diketopiperazines in the solid state, by X-ray crystal structure analysis, as well as by NMR studies in solution: to observe highly selective binding, the template needs to be not only conformationally rigid but it must have a specific turn geometry. The combination of combinatorial binding studies, X-ray crystal structure analysis, and NMR spectroscopy gave insight into why the trans,trans-diketopiperazine is a superior template compared to other diamines. Additionally, the results provide a guide for the rational design of two-armed receptors with good binding properties towards peptidic guests.