Wyniki wyszukiwania - Biblioteka Nauki

1

Zastosowanie metod QSAR do określania właściwości fizykochemicznych na przykładzie izomaślanu 3-hydroksy-2,2,4-trimetylopentylu

100%

Guziałowska-Tic J.

Przemysł Chemiczny

|

2017

|

tom T. 96, nr 8

1673--1676

PL

Porównano wyniki eksperymentalnych badań właściwości fizykochemicznych hydroksyestru HE-1 z wynikami pochodzącymi z narzędzia T.E.S.T. Stwierdzono, że narzędzie to może być wykorzystywane do określania gęstości oraz temperatury wrzenia. W tym przypadku błędy wyniosły odpowiednio 2,9 i 2,1%. W przypadku rozpuszczalności w wodzie i lepkości zgodność była niezadowalająca, a błędy wyniosły ponad 50%.

EN

D., b.p., water soly. and viscosity of the hydroxyester were detd. exptl. as well as by using a specialized computer software based on the quant. relationship between chem. structure and chem. activity to cf. the results obtained by both methods. The computer software was successfully used to det. d. and b.p. for which the relative errors were 2.9 and 2.1%, resp. In contrast, the conformity of water soly. and viscosity was not good enough and the relative errors exceeded 50%.

2

Toksykologia in silico – teoria i możliwości wykorzystania

100%

Stradecka A.

Przegląd Techniczny : Gazeta Inżynierska

|

2016

|

tom nr 8

15--16

PL

Artykuł omawia metody badań toksykologicznych in silico. Opisane zostały w nim modele badań oparte na zasadzie zależności struktura-aktywność (SAR) oraz inne przykłady wykorzystania modelowania matematycznego do oceny toksyczności substancji chemicznych.

EN

The following article gives examples of in silico methods used in modern toxicology. Described are models based on structure-activity relationships (SARs) and other uses of mathematical modeling used for assessing the toxicity of the compound.

3

Zastosowanie metod spektroskopowych w analizie QSAR

100%

Kalinowska M.

LAB Laboratoria, Aparatura, Badania

|

2011

|

tom R. 16, nr 6

10-14

4

2-Amino-4-arylthiazole Derivatives as Anti-giardial Agents: Synthesis, Biological Evaluation and QSAR Studies

94%

Mocelo-Castell R. , Villanueva-Novelo C. , Cáceres-Castillo D. , Carballo R. M. , Quijano-Quiñones R. F. , Quesadas-Rojas M. , Cantillo-Ciau Z. , Cedillo-Rivera R. , Moo-Puc R. E. , Moujir L. M. , Mena-Rejón G. J.

Open Chemistry

|

2015

|

tom 13

|

nr 1

EN

A series of seven 2-amino-4-arylthiazoles were prepared following Hantzsch’s modified method under microwave irradiation. A set of 50 derivatives was obtained and the in vitro activity against Giardia intestinalis was evaluated. The results on the biological activity revealed that, in general, the N-(5-bromo-4-aryl-thiazol-2-yl)-acetamide scaffold showed high bioactivity. In particular, compounds 6e (IC50 = 0.39 μM) and 6b (IC50 = 0.87 μM) were found to be more potent than the positive control metronidazole. Citoxicity and acute toxicity tests performed showed low toxicity and high selectivity of the most active compounds (6e SI = 139, 6b SI = 52.3). A QSAR analysis was applied to a data set of 37 obtained 2-amino-4-arylthiazoles derivatives and the best model described a strongly correlation between the anti-giardiasic activity and molecular descriptors as E2M, RDF115m, F10, MATS6v, and Hypnotic-80, with high statistical quality. This finding indicates that N-substituted aminothiazole scaffold should be investigated for the development of highly selective anti-giardial agent.

5

QSAR studies of 2-substituted 2,3-dihydro-1h-naphtho[1,8-de]-1,3,2-diazaphosphorine 2-oxides and sulphides

94%

Madhuritha A. , Kumar B. , Parthasarathy T. , Uma V.

Open Chemistry

|

2004

|

tom 2

|

nr 4

696-702

EN

A quantitative structure activity relationship (QSAR) study of 2-substituted 2,3-dihydro-1H-naphtho[1,8,de]-1,3,2-diazaphosphorine 2-oxides and sulphides (DND), examines the extent of the contribution by various physicochemical parameters with respect to their antimicrobial activity. Simple bivariant regression analysis, based on the least squares method, is applied in order to predict models. The predicted models reveal that the steric factor, MR, is the major contributor influencing antimicrobial activity. Bulky groups at the C-19 (C=0 group) position positively influence the potency of the compounds

6

Use of cluster analysis and rough set approaches in predicting toxicity of chemicals

94%

Dębska B.

Prace Instytutu Podstaw Informatyki Polskiej Akademii Nauk

|

2001

|

tom Nr 928

12-19

EN

The paper presented the applications of quantitive structure-activity relationships (QSAR) in environmental chemistry and toxicology. In this study, statistical and rough set methods have been applied to the development of QSAR models for estimating the acute aquatic toxicity of selected chemical compounds. Physicochemical and topostructural indices were used as properties relevant to the assessment of toxicity. These parameters have been used in the formulation of QSAR models for predicting toxicological properties. In the experimental part of the paper, results obtained in testing of ROSETTA toolkit and VVT module are presented. The rough set methodology were then used in selection and reduction the number of paramaters (chemical indexes described the selected compounds) before cluster analysis. Cluster analysis methods were used in unsupervised learning, classifying new compounds and predicting toxicity of chemicals. The results of test cases show that both give accaptable estimates for the toxicity of the compounds studied in this paper.

7

QSAR study of amine collectors for iron ore reverse flotation

94%

Wang B. , Xu X. , Duan H. , Wang X.

Physicochemical Problems of Mineral Processing

|

2019

|

tom Vol. 55, iss. 5

1059--1069

EN

In order to reveal the relationship between flotation behaviors of collectors and their structures, quantitative structure–activity relationship (QSAR) study about separation efficiency of quartz from hematite using amine collectors was performed. The genetic function approximation (GFA) algorithm was applied to generate the correlation models and model with acceptable R2 and Rcv2 (cross validated R-squared) correlation coefficients (R2=0.9666, Rcv2=0.9201) was developed. The model revealed that the Lowest Unoccupied Molecular Orbital (LUMO) energy of the molecule, the charge of nitrogen and the electronegativity of polar group were the major factors that affected the separation efficiency of collectors. The higher nitrogen charge, the larger electronegativity of polar group and the more positive of LUMO energy of amine collectors were, the higher separation efficiency would be.

8

QSAR modeling of antiradical and antioxidant activities of flavonoids using electrotopological state (E-State) atom parameters

94%

Ray S. , Sengupta C. , Roy K.

Open Chemistry

|

2007

|

tom 5

|

nr 4

1094-1113

EN

In the present paper QSAR modeling using electrotopological state atom (E-state) parameters has been attempted to determine the antiradical and the antioxidant activities of flavonoids in two model systems reported by Burda et al. (2001). The antiradical property of a methanolic solution of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and the antioxidant activity of flavonoids in a β-carotenelinoleic acid were the two model systems studied. Different statistical tools used in this communication are stepwise regression analysis, multiple linear regressions with factor analysis as the preprocessing step for variable selection (FA-MLR) and partial least squares analysis (PLS). In both the activities the best equation is obtained from stepwise regression analysis, considering, both equation statistics and predictive ability (antiradical activity: R 2 = 0.927, Q2 = 0.871 and antioxidant activity: R 2 = 0.901, Q2 = 0.841). [...]

9

QSAR modeling for lipid peroxidation inhibition potential of flavonoids using topological and structural parameters

94%

Ray S. , Sengupta C. , Roy K.

Open Chemistry

|

2008

|

tom 6

|

nr 2

267-276

EN

In the present study, Quantitative Structure-Activity Relationship (QSAR) modeling has been carried out for lipid peroxidation (LPO)-inhibition potential of a set of 27 flavonoids, using structural and topological parameters. For the development of models, three methods were used: (1) stepwise regression, (2) factor analysis followed by multiple linear regressions (FA-MLR) and (3) partial least squares (PLS) analysis. The best equation was obtained from stepwise regression analysis (Q2 = 0.626) considering the leave-oneout prediction statistics. [...]

10

QSAR studies of a number of triazole antifungal alcohols

94%

Nowaczyk A. , Modzelewska-Banachiewicz B.

Open Chemistry

|

2010

|

tom 8

|

nr 2

440-447

EN

The activity of fungicide agents containing a quinazolinone ring was described using the quantitative structure-activity relationship (QSAR) model by applying it to data taken from literature. The title compounds exhibit two important types of activity against certain fungal pathogens, i.e. activity against yeast and activity against filamentous fungi. A correlation between both antifungal activities (e.g. FA(yst) and FA(ff)) and physicochemical parameters such as the logarithm of the n-octanol/water partition coefficient (log P), the polarizability (P), the global minimum energy (TE), the energy difference between the frontier molecular orbital (DELH) and the molar refractivity (MR), was established using multiple linear regression. The molecular descriptors of the antifungal agents were obtained by quantum chemical calculations combined with molecular modeling calculations. Statistical analysis shows that the antifungal activity depends mainly on the calculated partition coefficients, log P, of the compounds. Bi-parametric models reveal that antifungal activity relates linearly to log P and P. [...]

11

Molecular modelling techniques in environmental research

84%

Urniaż R. D. , Rutkowska E. , Jastrzębski J. P. , Książek P. , Rudnicka K.

Environmental Biotechnology

|

2013

|

tom Vol. 9, No. 2

39--51

EN

Over the last few decades significant increase in computational methods (in silico) was annotated. Novel methods have been developed and applied for hypothesis improvement and testing in regions of industrial, pharmaceutical and environmental research. The term in silico methods include variety of approaches. Considerable attention has been attracted to databases, data analysis tools, quantitative structure-activity relationships (QSAR), pharmacophore models, molecular docking and dynamics, pharmacokinetics and other molecular modelling techniques. In silico methods are often accompanied by experimental data, both to create the model and to test it. Such models are frequently used in the discovery and optimization of novel molecules with expected affinity to a target, the estimation of absorption, distribution, metabolism, excretion and toxicity properties as well as physicochemical characterization. The review summarizes briefly the applications of most common molecular modelling techniques and evaluates their application in environmental research. Additionally, this study considers computer aided methods as potential and complex tools that may serve as valuable partnership with wet-lab experiments and may provide a rational aid to minimize the cost and time of research.

12

QSAR modelling toxicity toward rats of inorganic substances by means of CORAL

83%

Toropova A. , Toropov A. , Benfenati E. , Gini G.

Open Chemistry

|

2011

|

tom 9

|

nr 1

75-85

EN

CORAL (‘CORrelation And Logic’) is freeware available on the Internet www.insilico.eu/coral The aim of this program is to establish a correlation between an endpoint and descriptors calculated with a simplified molecular input line entry system (SMILES). Three models calculated by CORAL for toxicity towards rat (-pLD50) of inorganic substances (three random splits) have shown that CORAL could be a good tool to model this endpoint. The average statistical characteristics for the CORAL models are the following: n=38, r2=0.8461, q2=0.8298, s=0.273, F=198 (subtraining set); n=37, r2=0.8144, s=0.322, F=154 (calibration set); and n=10, r2=0.8004, Rm (test)2 =0.7815, s=0.240, F=32 (validation set). [...]

13

Degradation mechanism study of amine collectors in Fenton process by quantitative structure-activity relationship analysis

83%

Wang X. , Liu W. , Duan H. , Liu W.

Physicochemical Problems of Mineral Processing

|

2018

|

tom Vol. 54, iss. 3

713--721

EN

In this study, advanced oxidation processes (AOPs), Fenton process, was applied to degrade ten amine collectors. The experimental results indicated that most of the tested amines could be removed rapidly and effectively at pH=4, while the degradation of quaternary ammonium compounds was less than others. To research the Fenton oxidation process, the degradation-rate constants of amine collectors were calculated by the pseudo-second order kinetic model, then which was used as the dependent variable to establish a quantitative structure activity relationship (QSAR) model. Meanwhile, 16 molecular structure descriptors and quantum mechanical parameters for amine collectors were simulated and analyzed by using Materials Studio software. The optimum QSAR model was established based on the partial least squares regression (PLS) method and confirmed by the statistics analysis. The model revealed that hydrogen bond acceptor (HBA) and the maximum values of electrophilic attack in C atom sites (f(-)c) were the major effect factors for the degradation-rate constants of amine collector.

14

Experimental and modelling studies on antifungal compounds

83%

Doble M. , Kumar K.

Open Chemistry

|

2006

|

tom 4

|

nr 3

428-439

EN

Antifungal activity of organic compounds (aromatic, salicylic derivatives, cinnamyl derivatives etc) on Fusarium Rosium (14 compounds) and Aspergillus niger (17 compounds) was studied and QSAR models were developed relating molecular descriptors with the observed activity. Back propagation Neural Network models and single and multiple regression models were tested for predicting the observed activity. The data fit as well as the predictive capability of the neural network models were satisfactory (R2 = 0.84, q2 = 0.73 for Fusarium Rosium and R2 = 0.75, q2 = 0.62 for Aspergillus niger). The descriptors used in the network for the former were X4 (connectivity) and Jhetv (topological); and TIC1 (information) and SPI (topological) for the latter fungus. Antifungal activities of these organic compounds were generally lower against the latter than with the former fungus.

15

Analysis of the co-evolutions of correlations as a tool for QSAR-modeling of carcinogenicity: an unexpected good prediction based on a model that seems untrustworthy

83%

Toropova A. , Toropov A. , Diaza R. , Benfenati E. , Gini G.

Open Chemistry

|

2011

|

tom 9

|

nr 1

165-174

EN

To validate QSAR models an external test set is increasingly used. However the definition of the compounds for the test set is still debated. We studied, co-evolutions of correlations between optimal descriptors and carcinogenicity (pTD50) for the subtraining, calibration, and test set. Weak correlations for the sub-training set are sometimes accompanied by quite good correlations for the external test set. This can be explained in terms of the probability theory and can help define a suitable test set. The simplified molecular input line entry system (SMILES) was used to represent the molecular structure. Correlation weights for calculating the optimal descriptors are related to fragments of the SMILES. The statistical quality of the model is: n=170, r2=0.6638, q2=0.6554, s=0.828, F=331 (sub-training set); n=170, r2=0.6609, r2pred=0.6520, s=0.825, F=331 (calibration set); and n=61, r2=0.7796, r2pred=0.7658, Rm2=0.7448, s=0.563, F=221 (test set). The calculations were done with CORAL software (http://www.insilico.eu/coral/). [...]

16

QSAR modeling of anxiolytic activity taking into account the presence of keto- and enol-tautomers by balance of correlations with ideal slopes

83%

Toropova A. , Toropov A. , Benfenati E. , Gini G. , Leszczynska D. , Leszczynski J.

Open Chemistry

|

2011

|

tom 9

|

nr 5

846-854

EN

Optimal descriptors calculated with simplified molecular input line entry system (SMILES) have been examined as a tool for prediction of anxiolytic activity. Descriptors calculated with SMILES (a) of keto-isomers; (b) of enol-isomers; and (c) of both keto-isomers together with enol-isomers have been studied. Three approaches have been compared: 1. classic’ training-test’ system 2. balance of correlations and 3. balance of correlations with ideal slopes. The best statistical characteristics for the external validation set took place for optimal descriptors calculated with SMILES of both keto-form and enol-form (i.e., molecular structure was represented in the format: ’sMILES of keto-form. SMILES of enol-form’) by means of balance of correlations with ideal slopes. The predictive potential of this model was checked with three random splits. [...]

17

Investigation of 6-fluoroquinolones activity against Mycobacterium tuberculosis using theoretical molecular descriptors: a case study

83%

Minovski N. , Jezierska-Mazzarello A. , Vračko M. , Šolmajer T.

Open Chemistry

|

2011

|

tom 9

|

nr 5

855-866

EN

A quantitative structure-activity relationship (QSAR) study on a set of 66 structurally-similar 6-fluoroquinolones was performed using a large pool of theoretical molecular descriptors. Ab initio geometry optimizations were carried out to reproduce the geometrical and electronic structure parameters. The resulting molecular structures were confirmed to be minima via harmonic frequency calculations. Obtained atomic charges, HOMO and LUMO energies, orbital electron densities, dipole moment, energy and many other properties served as quantum-chemical descriptors. A multiple linear regression (MLR) technique was applied to generate a linear model for predicting the biological activity, Minimal Inhibitory Concentration (MIC), treated as negative decade logarithm, (pMIC). The heuristic method was used to optimize the model parameters and select the most significant descriptors. The model was tested internally using the CV LOO procedure on the training set and validated against the external validation set. The result (Q 2 ext = 0.7393), which was obtained on an external, previously excluded validation data set, shows the predictive performances of this model (R 2tr = 0.7416, Q 2 tr = 0.6613) in establishing (Q)SAR of 6-fluoroquinolones. This validated model could be proficiently used to design new 6-fluoroquinolones with possible higher activity. [...]

18

QSAR study of the DPPH· radical scavenging activity of coumarin derivatives and xanthine oxidase inhibition by molecular docking

83%

Razo-Hernández R. , Pineda-Urbina K. , Velazco-Medel M. , Villanueva-García M. , Sumaya-Martínez M. , Martínez-Martínez F. , Gómez-Sandoval Z.

Open Chemistry

|

2014

|

tom 12

|

nr 10

1067-1080

EN

A Quantitative Structure-Activity Relationship (QSAR) of coumarins by genetic algorithms employing physicochemical, topological, lipophilic and electronic descriptors was performed. We have used experimental antioxidant activities of specific coumarin derivatives against the DPPH· radical molecule. Molecular descriptors such as Randic Path/Walk, hydrophilic factor and chemical hardness were selected to propose a mathematical model. We obtained a linear correlation with R2 = 96.65 and Q LOO2 = 93.14 values. The evaluation of the predictive ability of the model was performed by applying the Q ASYM2, $\hat r^2 $ and Δr m2 methods. Fukui functions were calculated here for coumarin derivatives in order to delve into the mechanics by which they work as primary antioxidants. We also investigated xanthine oxidase inhibition with these coumarins by molecular docking. Our results show that hydrophobic, electrostatic and hydrogen bond interactions are crucial in the inhibition of xanthine oxidase by coumarins.

19

QSAR of caffeines by similarity cluster prediction

83%

Harsa T. , Harsa A. , Szefler B.

Open Chemistry

|

2014

|

tom 12

|

nr 3

365-376

EN

A novel QSAR approach based on correlation weighting and alignment over a hypermolecule that mimics the investigated correlational space was performed on a set of 40 caffeines downloaded from the PubChem database. The best models describing log P and LD50 values of this set of caffeine derivatives were validated against the external test set and in a new predictive model by using clusters of similarity.

20

Structure Activity Relationships, QSAR Modeling and Drug-like calculations of TP inhibition of 1,3,4-oxadiazoline-2-thione Derivatives

71%

Almi Z. , Belaidi S. , Lanez T. , Tchouar N.

International Letters of Chemistry, Physics and Astronomy

|

2014

|

tom Vol. 18

113--124

EN

QSAR studies have been performed on twenty-one molecules of 1,3,4-oxadiazoline-2-thiones. The compounds used are among the most thymidine phosphorylase (TP) inhibitors. A multiple linear regression (MLR) procedure was used to design the relationships between molecular descriptor and TP inhibition of the 1,3,4-oxadiazoline-2-thione derivatives. The predictivity of the model was estimated by cross-validation with the leave-one-out method. Our results suggest a QSAR model based of the following descriptors: logP, HE, Pol, MR, MV, and MW, qO1, SAG, for the TP inhibitory activity. To confirm the predictive power of the models, an external set of molecules was used. High correlation between experimental and predicted activity values was observed, indicating the validation and the good quality of the derived QSAR models.