Home About us Contact
|
Home About us Contact | ||
|
|
||
Activity Relationship Study (activity + relationship_study)
Selected AbstractsQuantitative Structure,Activity Relationship Study on Fish Toxicity of Substituted BenzenesMOLECULAR INFORMATICS, Issue 8 2008Zhiguo Gong Abstract Many chemicals cause latent harm, such as erratic diseases and change of climate, and therefore it is necessary to evaluate environmentally safe levels of dangerous chemicals. Quantitative Structure,Toxicity Relationship (QSTR) analysis has become an indispensable tool in ecotoxicological risk assessments. Our paper used QSTR to deal with the modeling of the acute toxicity of 92 substituted benzenes. The molecular descriptors representing the structural features of the compounds were calculated by CODESSA program. Heuristic Method (HM) and Radial Basis Function Neural Networks (RBFNNs) were utilized to construct the linear and the nonlinear QSTR models, respectively. The predictive results were in agreement with the experimental values. The optimal QSTR model which was established based on RBFNNs gave a correlation coefficient (R2) of 0.893, 0.876, 0.889 and Root-Mean-Square Error (RMSE) of 0.220, 0.205, 0.218 for the training set, the test set, and the whole set, respectively. RBFNNs proved to be a very good method to assess acute aquatic toxicity of these compounds, and more importantly, the RBFNNs model established in this paper has fewer descriptors and better results than other models reported in previous literatures. The current model allows a more transparent chemical interpretation of the acute toxicity in terms of intermolecular interactions. [source] Structure-hepatoprotective activity relationship study of sesquiterpene lactones: A QSAR analysisINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 1 2009Yuliya Paukku Abstract This study has been carried out using quantitative structure-activity relationship analysis (QSAR) for 22 sesquiterpene lactones to correlate and predict their hepatoprotective activity. Sesquiterpenoids, the largest class of terpenoids, are a widespread group of substances occurring in various plant organisms. QSAR analysis was carried out using methods such as genetic algorithm for variables selection among generated and calculated descriptors and multiple linear regression analysis. Quantum-chemical calculations have been performed by density functional theory at B3LYP/6-311G(d, p) level for evaluation of electronic properties using reference geometries optimized by semi-empirical AM1 approach. Three models describing hepatoprotective activity values for series of sesquiterpene lactones are proposed. The obtained models are useful for description of sesquiterpene lactones hepatoprotective activity and can be used to estimate the hepatoprotective activity of new substituted sesquiterpene lactones. The models obtained in our study show not only statistical significance, but also good predictive ability. The estimated predictive ability (r) of these models lies within 0.942,0.969. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Quantitative structure,activity relationship study on the inhibitors of fatty acid amide hydrolaseJOURNAL OF CHEMOMETRICS, Issue 9 2010Peng Lu Abstract A quantitative structure activity relationship (QSAR) analysis was performed on the values of a series of fatty acid amide hydrolase (FAAH) inhibitors. Six molecular descriptors selected by CODESSA software were used as inputs to perform heuristic method (HM) and support vector machine (SVM). The results obtained by SVM were compared with those obtained by the HM. The root mean square errors (RMSEs) for the training set given by HM and SVM were 0.555 and 0.404, respectively, which shows that the performance of the SVM model is better than that of the HM model. This paper provides a new and effective method for predicting the activity of FAAH inhibitors. Copyright © 2010 John Wiley & Sons, Ltd. [source] Synthesis and biological properties of the seven alanine-modified analogues of the marine cyclopeptide hymenamide CJOURNAL OF PEPTIDE SCIENCE, Issue 8 2002Assunta Napolitano Abstract The synthesis and biological activity of the marine cyclopeptide hymenamide C(1), showing an inhibitory effect on human neutrophil elastase degranulation release, were recently described. Based on this result, it was decided to undertake a systematic structure,activity relationship study of this cyclopeptide, based on the Ala-scan technique, in order to obtain useful information for the rational design of additional analogues. The synthesis and characterization of the seven Ala modified analogues are reported and their biological and pharmacological properties are described. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd. [source] Structure,activity relationship study of alkynyl ether insecticide synergists and the development of MB-599 (verbutin),PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 4 2003Béla Bertók Abstract Structure,activity relationships of aryl alkynyl synergists of the general formula of Ar,Q,R, where Q represents a bridging structure, were studied using a standardised testing system and Relative Potency values. Ethers, esters, oxime ethers, amides and amines were prepared and evaluated. The length of the R-alkynyl chain, the role of the bridge and the substitution of the aromatic ring were examined systematically. The most potent compounds possessed an aromatic ring connected via a bridge of three atoms to an alkynyl chain, forming together a linear side-chain of six atoms. Several highly potent compounds were synthesised of which one (MB-599; proposed common name verbutin) was selected for development as a selective insecticide synergist in crop protection. Its high potential at practical insecticide:synergist ratios makes possible the reduction of the total amount of insect-control chemicals applied, and its use as an additive to produce new formulations of existing insecticides makes it highly advantageous in resistance management, giving a new tool to sustain the effectiveness of a wide range of insecticides. A product containing a (1,+,1) mixture of verbutin and beta-cypermethrin was launched in Hungary in 2002. © 2003 Society of Chemical Industry [source] Exploring QSAR for Substituted 2-Sulfonyl-Phenyl-Indol Derivatives as Potent and Selective COX-2 Inhibitors Using Different Chemometrics ToolsCHEMICAL BIOLOGY & DRUG DESIGN, Issue 6 2008Mehdi Khoshneviszadeh Selective inhibition of cyclooxygenase-2 inhibitors is an important strategy in designing of potent anti-inflammatory compounds with significantly reduced side effects. The present quantitative structure,activity relationship study, attempts to explore the structural and physicochemical requirements of 2-sulfonyl,phenyl,indol derivatives (n = 30) for COX-2 inhibitory activity using chemical, topological, geometrical, and quantum descriptors. Some statistical techniques like stepwise regression, multiple linear regression with factor analysis as the data preprocessing (FA-MLR), principal component regression analysis, and genetic algorithms partial least squares analysis were applied to derive the quantitative structure,activity relationship models. The generated equations were statistically validated using cross-validation and external test set. The quality of equations obtained from stepwise multiple linear regression, FA-MLR, principal component regression analysis and PLS were in the acceptable statistical range. The best multiple linear regression equation obtained from factor analysis (FA-MLR) as the preprocessing step could predict 77.5% of the variance of the cyclooxygenase-2 inhibitory activity whereas that derived from genetic algorithms partial least squares could predict 84.2% of variances. The results of quantitative structure,activity relationship models suggested the importance of lipophilicity, electronegativity, molecular area and steric parameters on the cyclooxygenase-2 inhibitory activity. [source] Structure,Activity Relationship Studies on Derivatives of Eudesmanolides from Inula helenium as Toxicants against Aedes aegypti Larvae and AdultsCHEMISTRY & BIODIVERSITY, Issue 7 2010Charles Abstract An Aedes aegypti larval toxicity bioassay was performed on compounds representing many classes of natural compounds including polyacetylenes, phytosterols, flavonoids, sesquiterpenoids, and triterpenoids. Among these compounds, two eudesmanolides, alantolactone, and isoalantolactone showed larvicidal activities against Ae. aegypti and, therefore, were chosen for further structure,activity relationship study. In this study, structural modifications were performed on both alantolactone and isoalantolactone in an effort to understand the functional groups necessary for maintaining and/or increasing its activity, and to possibly lead to more effective insect-control agents. All parent compounds and synthetic modification reaction products were evaluated for their toxic activities against Ae. aegypti larvae and adults. Structure modifications included epoxidations, reductions, catalytic hydrogenations, and Michael additions to the ,,, -unsaturated lactones. None of the synthetic isomers synthesized and screened against Ae. aegypti larvae were more active than isoalantolactone itself which had an LC50 value of 10.0,,g/ml. This was not the case for analogs of alantolactone for which many of the analogs had larvicidal activities ranging from 12.4 to 69.9,,g/ml. In general, activity trends observed from Ae. aegypti larval screening were not consistent with observations from adulticidal screening. The propylamine Michael addition analog of alantolactone was the most active adulticide synthesized with an LC50 value of 1.07,,g/mosquito. In addition, the crystal structures of both alantolactone and isoalantolactone were determined using CuK, radiation, which allowed their absolute configurations to be determined based on resonant scattering of the light atoms. [source] DNA Topoisomerase I Inhibitory Alkaloids from Corydalis saxicolaCHEMISTRY & BIODIVERSITY, Issue 7 2008Xuanxuan Cheng Abstract Chemical studies of the Chinese herb Corydalis saxicolaBunting led to the isolation and identification of 14 alkaloids, 1,14. Seven of these compounds, 4,9 and 11, were obtained from this plant for the first time. Feruloylagmatine (7) is the first guanidine-type alkaloid to be identified in the family Papaveraceae and in dicotyledonous plants. All of the isolated compounds were assayed for inhibitory activity against human DNA topoisomerase I. A DNA cleavage assay demonstrated that these alkaloids specifically inhibit topoisomerase through stabilization of the enzyme,DNA complex. Among the isolated alkaloids, (,)-pallidine (8) and (,)-scoulerine (11) showed strong inhibitory activities toward topoisomerase I that were comparable to camptothecin, a typical topoisomerase I inhibitor. A preliminary structure,activity relationship study suggested that the quaternary ammonium ion might play an important role in topoisomerase I inhibition by the isoquinoline alkaloids. These data indicated that DNA topoisomerase I inhibition represents probably one of the anticarcinogenic mechanisms of C. saxicola. [source] | ||||||||||