Studies on the Synthesis, Anticonvulsant Activity, and the Structure-Activity Relationships of Phenyl Pyridazinones and their GABA Derivatives

In searching for effective anticonvulsant agents,fourteen 6-aryl-4.5-di- hydro-3(2H)pyridazinones.fifteen 6-aryl-3(2H)pyridazinones,and seventeen 3-GABA derivatives of 6-aryIpyridazines have been synthesized,and evaluated in mice for the ability to antagonize maximal electroshock seizure(MES).The ED_(50) values showed that 6-(2′,4′- dichlorophenyt)-3(2H)pyridazinone was the most potent anticonvulsant among these corn- pounds(ED_(50)=10.15 mg/kg).The structure-activity relationships of the aryl pyridazinones were studied.The result showed that:(1)the higher the value of the hydrophobic parameter л of the substituent on the phenyl ring.the more potent the anticonvulsant activity of the corn- pound.and(2)only the compounds with an electron withdrawing substituent on the phenyl ring exhibited appreciable anticonvulsant activity.

Theoretical Investigation on QSAR of(2-Methyl-3-biphenylyl)methanol Analogs as PD-L1 Inhibitor

Cancer is one of the most serious issues in human life.Blocking programmed cell death protein 1 and programmed death ligand-1(PD-L1)pathway is one of the great innovations in the last few years,a few numbers of inhibitors can be able to block it.(2-Methyl-3-biphenylyl)methanol derivative is one of them.Here,the quantitative structure-activity relationship(QSAR)established twenty(2-methyl-3-biphenylyl)methanol derivatives as the programmed death ligand-1 inhibitors.Density functional theory at the B3LPY/6-31+G(d,p)level was employed to study the chemical structure and properties of the chosen compounds.Highest occupied molecular orbital energy EHOMO,lowest unoccupied molecular orbital energy ELUMO,total energy ET,dipole moment DM,absolute hardnessη,absolute electronegativityχ,softness S,electrophilicityω,energy gap?E,etc.,were observed and determined.Principal component analysis(PCA),multiple linear regression(MLR)and multiple nonlinear regression(MNLR)analysis were carried out to establish the QSAR.The proposed quantitative models and interpreted outcomes of the compounds were based on statistical analysis.Statistical results of MLR and MNLR exhibited the coefficient R^2 was 0.661 and 0.758,respectively.Leave-one-out cross-validation,r_m^2 metric,r_m^2 test,and"Golbraikh&Tropsha’s criteria"analyses were applied for the validation of MLR and MNLR,which indicate two models are statistically significant and well stable with data variation in the external validation towards PD-L1.The obtained results showed that the MNLR model predicts the bioactivity more accurately than MLR,and it may be helpful and supporting for evaluation of the biological activity of PD-L1 inhibitors.

QSAR of Estrogen of Bisphenol A with 3D Vector of Atomic Property Correlation

Considering atomic property vector and atomic correlative function, the 3-dimensional structural vector of atomic property correlation （3D-VAPC）, a novel descriptor,is defined to characterize a 3-dimensional molecular structure by introducing self-adaptability regulation mechanism and the idea of orientating to customers. Characterizing the structures of 25 bisphenol A compounds by this vector, the QSAR models of three kinds of estrogen activities （ER affinities, gene induction and cell proliferation） have high multiple correlation coefficient （Rcum^2=0.933, 0.813, 0.959） and cross verification coefficient （Qcum^2=0.847, 0.953, 0.798） by support vector machine （SVM）, which suits for nonlinear circumstances. The above results show that the models successfully express the correlation between structure and three kinds of estrogen activities. Therefore, 3D-VAPC exactly reflects the molecular structural information and SVM method correctly describes the correlation between information and property of the compounds.

Pharmacokinetic evaluation,molecular docking and in vitro biological evaluation of 1,3,4-oxadiazole derivatives as potent antioxidants and STAT3 inhibitors

1, 3, 4-Oxadiazole derivatives(4 a–5 f) were previously synthesized to investigate their anticancer properties.However, studies relating to their antioxidant potential and signal transducer and activator of transcription(STAT) inhibition have not been performed. We investigated previously synthesized 1, 3, 4-oxadiazole derivatives(4 a–5 f) for various radical scavenging properties using several in vitro antioxidant assays and also for direct inhibition of STAT3 through molecular docking. The data obtained from various antioxidant assays such as 2, 2,-diphenyl-1-picrylhydrazyl radical(DPPH), nitric oxide, hydrogen peroxide, and superoxide anion radical revealed that among all the derivatives, compound 5 e displayed high antioxidant activities than the standard antioxidant L-ascorbic acid. Additionally, the total reduction assay and antioxidant capacity assay further confirmed the antioxidant potential of compound 5 e. Furthermore, the molecular docking studies performed for all derivatives along with the standard inhibitor STX-0119 showed that binding energy released in direct binding with the SH2 domain of STAT3 was the highest for compound 5 e(-9.91 kcal/mol).Through virtual screening, compound 5 e was found to exhibit optimum competency in inhibiting STAT3 activity. Compound 5 e decreased the activation of STAT3 as observed with Western blot. In brief, compound5 e was identified as a potent antioxidant agent and STAT3 inhibitor and effective agent for cancer treatment.

Support vector classification for SAR of 5-HT3 receptor antagonists

In this work, support vector classification （SVC） algorithm was used to build structure-activity relationship （SAR） model of the 5-hydroxytryptamine type 3 （5-HT3 ） receptor antagonists with 26 compounds. In a benchmark test, SVC was compared with several techniques of machine learning currently used in the field. The prediction performance of the model was discussed on the basis of the leave-one-out cross-validation. The results show that the accuracy of prediction of SVC model was higher than those of back propagation artificial neural network （BP ANN）, K-nearest neighbor （KNN） and Fisher methods.

3D-QSAR Study on the Inhibitory Activity of Flavonoids on PIM-1 Kinase

20 Typical flavonoids were selected for study on the interaction between them and PIM-1 kinase with the comparative molecular field analysis method（CoMFA） as well as the comparative molecular similarity index analysis method（CoMSIA） based on molecule docking.3D-QSAR models between these flavonoids and receptor PIM-1 kinase were established.The obtained optimal cross-validation correlation coefficient Q2 for CoMFA model was 0.582,and the non-cross-validation correlation coefficient R2 was 0.955;the corresponding values for CoMSIA model were 0.790 and 0.974,respectively.These two models showed fairly fine stability and predictive ability.In addition,molecule docking results revealed the key residues in the receptor cavity and their specific action ways with flavonoids.

QSAR Study on Some N-[5-(2-Furanyl)-2-methyl-4-oxo-4H-thieno[2,3-d]pyrimidin-3-yl]-carboxamide and 3-Substituted-5-(2-furanyl)-2-methyl-3H-thieno-[2,3-d]pyrimidin-4-ones Using Three-dimensional Holographic Vector of Atomic Interaction Field

Study on the quantitative structure-activity relationship （QSAR） of 26 compounds, N-[5-（2-furanyl）-2-methyl-4-oxo-4H-thieno[2,3-d]pyrimidin-3-yl]-carboxamide and 3-substituted- 5-（2-furanyl）-2-methyl-3H-thieno[2,3-d]pyrimidin-4-ones, with three-dimensional holographic vector of atomic interaction field （3D-HoVAIF） was carried out. SMR-PLS QSAR models have been created and good correlation coefficients and cross-validated correlation coefficients were obtained. The result shows that the models have good prediction capability and favorable stability and the 3D-HoVAIF is applicable to the molecular structural characterization and biological activity prediction.

Quantitative Structure Activity Relationship Studies of Benzoxazinone Derivative Antithrombotic Drug Using New Three-dimensional Structure Descriptors

A novel three-dimensional holographic vector of atomic interaction field（3D-HoVAIF） was used to describe the chemical structures of 23 benzoxazinone derivatives as antithrombotic drugs.Here a quantitative structure activity relationship（QSAR） model was built by partial least-squares（PLS） regression.The estimation stability and prediction ability of the model were strictly analyzed by both internal and external validations.The correlation coefficients of established PLS model,leave-one-out（LOO） cross-validation,and predicted values versus experimental ones of external samples were R2=0.899,RCV2=0.854 and Qext2=0.868,respectively.These values indicated that the built PLS model had both favorable estimation stability and good prediction capabilities.Furthermore,the satisfactory results showed that 3D-HoVAIF could preferably express the information related to the biological activity of benzoxazinone derivatives.

Molecular docking study of xylogranatins binding to glycogen synthase kinase-3β

Objective The mangrove tree Xylocarpus granatum J.Koenig(X.granatum)is a medicinal plant used to treat various diseases in several Asian countries.Many bioactive natural products have been isolated from the plants,particularly several groups of limonoids,including 18 xylogranatins(Xyl-A to R),all of which bear a furyl-δ-lactone core commonly found in limonoids.Based on a structural analogy with the limonoids obacunone and gedunin,we hypothesized that xylogranatins could target the enzyme glycogen synthase kinase-3β(GSK-3β),a major target for the treatment of neurodegenerative pathologies,viral infections,and cancers.Methods We investigated the binding of the 18 xylogranatins to GSK-3βusing molecular docking in comparison with two known reference GSK-3βATP-competitive inhibitors,LY2090314 and AR-A014418.For each compound bound to GSK-3β,the empirical energy of interaction(ΔE)was calculated and compared to that obtained with known GSK-3βinhibitors and limonoid triterpenes that target this enzyme.Results Five compounds were identified as potential GSK-3βbinders,Xyl-A,-C,-J,-N,and-O,for which the calculated empiricalΔE was equivalent to that calculated using the best reference molecule AR-A014418.The best ligand is Xyl-C,which is known to have marked anticancer properties.Binding of Xyl-C to the ATP-binding pocket of GSK-3βpositions the furyl-δ-lactone unit deep into the binding-site cavity.Other xylogranatin derivatives bearing a central pyridine ring or a compact polycyclic structure are much less adapted for GSK-3βbinding.Structure-binding relationships are discussed.Conclusion GSK-3βmay contribute to the anticancer effects of X.granatum extract.This study paves the way for the identification of other furyl-δ-lactone-containing limonoids as GSK-3βmodulators.

Synthesis, Characterization, and Antifungal Evaluation of Thiolactomycin Derivatives

5-Substituted benzylidene 3-acylthiotetronic acids are antifungal.A series of 3-acylthiotetronic acid derivatives with varying substitutions at the 5-position were designed,synthesized,and characterized,based on the binding pose of 3-acyl thiolactone with the protein C171Q KasA.Fungicidal activities of these compounds were screened against Valsa Mali,Curvularia lunata,Fusarium graminearum,and Fusarium oxysporum f.sp.lycopersici.Most target compounds exhibited excellent fungicidal activities against target fungi at the concentration of 50μg·mL-1.Compounds 11c and 11i displayed the highest activity with a broad spectrum.The median effective concentration(EC50)values of 11c and 11i were 1.9–10.7 and 3.1–7.8μg·mL-1,respectively,against the tested fungi,while the EC50 values of the fungicides azoxystrobin,carbendazim,and fluopyram were respectively 0.30,4.22,and>50μg·mL-1 against V.Mali;6.7,41.7,and 0.18μg·mL-1 against C.lunata;22.4,0.42,and 0.43μg·mL-1 against F.graminearum;and 4.3,0.12,and>50μg·mL-1 against F.oxysporum f.sp.lycopersici.The structures and activities of the target compounds against C.lunata were analyzed to obtain a statistically significant comparative molecular field analysis(CoMFA)model with high prediction abilities(q2=0.9816,r2=0.8060),and its reliability was verified.The different substituents on the benzylidene at the 5-position had significant effects on the activity,while the introduction of a halogen atom at the benzene ring of benzylidene was able to improve the activity against the tested fungi.

QSAR Studies on Influenza Neuraminidase Inhibitors——Acylthiourea Analogue

The quantitative structure-activity relationship （QSAR） of 30 acylthiourea analogues was studied by using a three-dimensional holographic vector of atomic interaction field （3D-HoVAIF） to describe their chemical structures. The descriptors obtained were screened by stepwise multiple regression （SMR） and a partial least-squares （PLS） regression model was built. The correlation coefficient r^2 of the established model and Leave-One-Out （LOO） Cross-Validation （CV） correlation coefficient q^2 are 0.624 and 0.409, respectively. The model has favorable stability and good prediction capability, and further QSAR analysis showed that hydrophobic interaction has the most important effect on the activity of acylthiourea analogue and 3D-HoVAIF was applicable to the molecular structural characterization and biologicalactivity prediction.

Synthesis and cytotoxic activity of 3, 4, 11-trihydroxyl modified derivatives of bergenin

To synthesize a series of 3-, 4-, and/or 11-trihydroxy modified bergenin derivatives and evaluated their cytotoxic activity in vitro. The phenolic hydroxyl groups of bergenin were protected by benzyl groups with benzyl bromide. Treatment of dibenzyl bergenin with the corresponding acid in the presence of EDC·HCl and DMAP in CH2Cl2, followed by hydrogenation over Pd/C catalysts, afforded derivatives of bergenin esters. All of the target compounds were identified by IR, MS, and 1H NMR. Twenty-six novel and three known derivatives of bergenin esters were synthesized. Their cytotoxicity values were evaluated by the MTT assay on the inhibition of DU-145 and BGC-823 cells in vitro. Several triply-substituted(3a, 4a, 5a, 6a, 7a) and doublysubstituted(8b, 9b) bergenin derivatives exhibited higher cytotoxic activity than bergenin. The result showed that the size of substituents and the lipophilicity of the bergenin esters displayed an important role on their cytotoxic activity.

Study on the Biological Activity of 3-Aroyl-5-substituted Thiophene Derivatives Based on the CoMFA Method

A three-dimensional quantitative structure-activity relationship(3 D-QSAR) study was conducted to analyze the A1 AR density(Bmax) of 56 3-aroyl-5-substituted thiophene derivatives(ASTDs) in human A1 Chinese hamster ovary(hA1 CHO) membranes by the comparative molecular field analysis(CoMFA) method. A training set of 45 compounds was used to establish the predictive model, which was verified by the test set of 17 compounds containing template molecule and 5 newly designed molecules. The cross-validation(R2 cv) and non-cross-validation(R2) coefficients of the training set were 0.655 and 0.959, respectively. The model was used to predict the activities of the compounds of the training and test sets, and the results indicated that the models had strong stability and good prediction ability. According to model analysis, the contribution of steric and electrostatic fields was 51.4% and 48.6%, respectively. Based on the 3 D contour maps, five excellent ASTDs agonists were designed, which need to be further verified by biomedical experiments.

Design, Synthesis and Evaluation of Substituted N-（3-Arylpropyl）-9,10-dihydro-9-oxoacridine-4-carboxamides as Potent MDR Reversal Agents in Cancer

A novel class of molecules with structure N-（3-arylpropyl）-9,10-dihydro-9-oxoacridine-4-carboxamides （20- 29） were designed by generating a pharmacophore for potent MDR reversal activity using phase drug design software. The designed molecules were synthesized by a novel synthesis route and evaluated for their inhibitory effects on the transport activity of P-glycoprotein （P-gp） by standard Hoechst 33342 assay method. Based on the pIC50 values of ten title compounds screened, three compounds exhibited better activity as compared to Verapamil used as standard.

Isoform Selective PI3K-beta Inhibitors

Although PI3K/AKT has undoubtedly been one of the most important pathways that impact tumorigenesis and proliferation, PI3K-beta has not been considered as a stand-alone target for potential cancer treatment until the re-cent discovery of the key role that PI3K-beta plays in phosphatase and TENsin homolog （PTEN）-deficient tumors. Medicinal chemistry efforts from the pharmaceutical industry and academia in the past few years have led to sig-nificant advancements in understanding beta isoform selectivity and in the development of a clinical drug candidate.

The design, synthesis and α7 nicotinic acetylcholine receptors positive allosteric modulative evaluation of 3H-quinazolin-4-one derivatives

A series of new 6-substituted 3 H-quinazolin-4-ones（3 a-3 d） were designed, synthesized and evaluated as the type I positive allosteric modulators（PAMs） of human α7 n ACh R expressed in Xenopus ooctyes by two-electrode voltage clamp. However, no compound showed a better efficacious PAM than lead compound 2 in the presence of acetylcholine（100 μM）. The structure-activity relationship（SAR） analysis suggested that thiazolo[4,5-d]pyrimidin-7（6 H）-one was the key biological skeleton.

Synthesis and biological evaluation of 4-methyl-1,2,3-thiadiazole-5-carboxaldehyde benzoyl hydrazone derivatives

To find new lead compounds with high biological activity,a series of novel 4-methyl-1,2,3-thiadiazole-5-carboxaldehyde benzoyl hydrazone derivatives were designed and synthesized.Their structures were confirmed by -1H NMR,-（13）C NMR,IR spectrum and elemental analysis.Preliminary bioassay indicated that the title compounds exhibited moderate to strong fungicidal activity against six fungi in vitro at50 μg/mL.Moreover,some of the title compounds exhibited good curative activity against TMV in vivo at500 μg/mL.The structure-activity relationship analysis of compounds against Valsa mali showed that compounds containing halogen at the para position on phenyl exhibited the best activity.Especially compound 8k showed broad spectrum fungicidal activities against Valsa mali,Botrytis cinerea,Pythium aphamdermatum,Rhizoctonia solani,Fusarium moniliforme and Altemaria solani with the EC（50） values of8.20,24.42,15.80,40.53,41.48,and 34.16 μg/mL,respectively.

Synthesis and biological evaluation of indole-3-carboxamide derivatives as antioxidant agents

Oxidative stress results in various pathologies and as consequence antioxidant agents have attracted uninterrupted attention.In this paper,a novel series of indole-3-carboxamide derivatives(6 a-61) were designed and synthesized based on the melatonin structure as novel antioxidants.All of them were evaluated for the antioxidant activities in vitro against human neuroblastoma SH-SY5 Y cell line using H2 O2 radical scavenging assay.The target compounds 6 a,6 f and 6 i indicated better activities than the positive control,ascorbic acid,and 6 a exhibited the best antioxidant activity.In addition,the structureactivity relationships of the target compounds were also preliminarily summarized based on the obtained experimental data.

3D-QSAR studies on glycogen phosphorylase inhibitors by flexible comparative molecular field analysis

Canceling grids accommodating probes in comparative molecular field analysis (CoMFA), the idea of flexibleness is introduced into the CoMFA, and in combination with swarm intelligent algorithm which attempts to optimize distributions of diverse probes around drug molecules, a new 3D-QSAR method is proposed in this context as flexible comparative molecular field analysis (FCoMFA). In preliminary at-tempts to performing QSAR studies on 47 glycogen phosphorylase inhibitors, FCoMFA is employed and confirmed to be potent to exploring ligand-receptor interaction manners at active positions and thus to generating stable and predictable models. Simultaneously by an intuitive graphics regarding probe distribution patterns, impacts of different substituted groups on activities is also given an insight into.

Key Parameters Analysis and Regulation of Singlet Oxygen Quenching Rate of Carotenoids

28 kinds of carotenoids are studied to reveal the key parameters and regulation on the singlet oxygen quenching rate.First,the quantum chemistry parameters of carotenoids calculated by Gaussian software combined with substitution parameters were used to construct the quantitative structure-activity relationship model(QSAR)of the singlet oxygen quenching rate of carotenoids.The key parameters affecting the antioxidant activity of carotenoids are revealed,and the data predicted via the QSAR model were provided for subsequent research.Then,a three-dimensional(3D)pharmacophore model was used to regulate and modify the antioxidant activity of carotenoids.The correlation coefficients of the modeling group(R2)and verification group(Rpre2)of the established QSAR model were 0.945 and 0.916,respectively,which can be used for the analysis of antioxidant activity of carotenoids;the antioxidant activity of carotenoids can be significantly regulated by the number of conjugated C=C bonds,the energy difference between frontier molecular orbitals and the partial Mulliken charge in C1 and theπ···π*excitation energy E(s);the antioxidant activity of carotenoids can be effectively regulated by the hydrogen bond acceptor pharmacophores on both sides of the conjugated C=C bonds and the hydrophobic groups on the conjugated C=C bond;the hydrophobic substituents attached to conjugated C=C bonds can effectively improve the singlet oxygen quenching rate of carotenoids.