Using the GUSAR program, structure-activity relationships on inhibition of cyclooxygenase-2 (COX-2) catalytic activity were quantitatively analyzed for twenty-six derivatives of 4,5,6,7-tetrahydro-2H-isoindole, 2,3-dihydro-1H-pyrrolyzine, and benzothiophene in the concentration range of 0.6-700 nmol/liter IC50 values. Six statistically significant consensus QSAR models for prediction of IC50 values were designed based on MNA- and QNA-descriptors and their combinations. These models demonstrated high accuracy in the prediction of IC50 values for structures of both training and test sets. Structural fragments of the COX-2 inhibitors capable of strengthening or weakening the desired property were determined using the same program. This information can be taken into consideration on molecular design of new COX-2 inhibitors. It was shown that in most cases, the influence of structural fragments on the inhibitory activity of the studied compounds revealed with the GUSAR program coincided with the results of expert evaluation of their effects based on known experimental data, and this can be used for optimization of structures to change the value of their biological activity.
The antioxidant properties of humic substances of low-mineralization sulfidic muds (peloids) were investigated using initiated oxidation of 1,4-dioxane as a model reaction. Four groups of substances including humic, himatomelanic, fulvic, and humus acids were studied. Kinetic characteristics of the oxidation of humic substances were determined in terms of effective inhibition rate constants fk In . It is established that himatomelanic acids of peloids exhibit the maximum antioxidant activity among the studied substances.
A quantitative analysis of the structure-antioxidant activity relationship was performed for 128 derivatives of phenols, amines, uracil, benzopyrane, and benzofuran using the GUSAR 2013 program. Nine statistically signifi cant QSAR consensus models characterized by a high accuracy of prediction of the chain termination rate constant of oxidation on the antioxidant molecules were constructed. The results of the structural analysis performed in the GUSAR 2013 program are in good agreement with the literature data.
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