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Inactive Compounds (inactive + compound)
Selected AbstractsDifferent antibacterial actions of isoflavones isolated from Erythrina poeppigiana against methicillin-resistant Staphylococcus aureusLETTERS IN APPLIED MICROBIOLOGY, Issue 3 2006M. Sato Abstract Aims:, To screen six isoflavones isolated from Erythrina poeppigiana (Leguminosae) for their antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Methods and Results:, Stem bark of E. poeppigiana was macerated with acetone and the methylene chloride-soluble fraction of the residue was applied to repeated silica gel column chromatography and eluted. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by a broth dilution method. Inactive compounds that failed inhibiting bacterial growth at 25 ,g ml,1 were further investigated for their combination effects with methicillin and oxacillin. Of the isolated isoflavones, 5,7,4,-trihydroxy-8,3,-di(,,, -dimethylallyl)isoflavone (isolupalbigenin) exhibited the highest anti-MRSA activity (MICs: 1·56,3·13 ,g ml,1; MBCs: 6·25,12·5 ,g ml,1), followed by 5,7,4,-trihydroxy-6- ,,, -dimethylallylisoflavone (erythrinin B). Inactive compounds were combined with methicillin or oxacillin, 5,4,-dihydroxy-(3,,,4,,-dihydro-3,,-hydroxy)-2,,,2,,-dimethylpyrano[5,,,6,,:6,7]isoflavone (M-Wi-2) intensifying the susceptibility of MRSA strains to these antibiotics. In all but one strain, the MIC values of methicillin were reduced from ,100 to 6·25,12·5 ,g ml,1 in the presence of M-Wi-2 (25 ,g ml,1). Conclusions:, Isoflavones from E. poeppigiana showed two different antibacterial activities against MRSA: direct growth inhibition and intensification of methicillin sensitivity. Significance and Impact of the Study:, Isolupalbigenin and M-Wi-2 could lead to the development of compounds for new approaches against MRSA infection. [source] Effects of anthocyanins and other phenolics of boysenberry and blackcurrant as inhibitors of oxidative stress and damage to cellular DNA in SH-SY5Y and HL-60 cellsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2006Dilip Ghosh Abstract There is growing interest both from consumers and researchers in the role that berries play in human health. The objective of this study was to investigate whether anthocyanins and other phenolics present in boysenberries and blackcurrants are effective in protecting cells against the oxidative damage induced by hydrogen peroxide (H2O2). The concentrations of polyphenols used were within the human physiological range. The data showed that SH-SY5Y human neuroblastoma cells were protected against H2O2 -induced toxicity by the anthocyanins and phenolic fractions. The concurrent addition of either fractions of these berries with H2O2 significantly inhibited the increase in intracellular reactive oxygen species (ROS) production. Pre-incubation of cells with the same concentrations had no effect on the ROS level,a result that may be due to the metabolic conversion to inactive compounds. Anthocyanins and phenolic fractions of blackcurrant were better at protecting DNA of HL-60 human promyelocytic cells from damage than similar fractions from boysenberry. The phenolic extract of blackcurrant demonstrated the highest protective effect against H2O2 -induced neurotoxicity, oxidative stress and DNA damage and may be a good candidate for inclusion into a processed functional food. Copyright © 2006 Society of Chemical Industry [source] Theoretical Prediction of the Phenoxyl Radical Formation Capacity and Cyclooxygenase Inhibition Relationships by Phenolic CompoundsMOLECULAR INFORMATICS, Issue 6 2002Juan Ruiz Abstract Due to the importance of the O-H bond dissociation in the antioxidant mechanism of anti-inflammatory phenols, we studied the biradical process Ph-OH,PhO.+H. for 25 phenolic compounds using ab initio calculations. Enthalpies of reaction (,Hr), changes in the electron density at the O-H bond critical point (,OH) and total atomic charges of ortho and para carbon atoms strongly correlate with the in vitro inhibition of cyclooxygenase activity by phenols. The most active compounds have large values of the electron density at the O-H bond (,OH), thus favouring the O-H bond dissociation. In contrast, inactive compounds have small values of the electron density at the O-H bond (,OH), thus reducing the hydrogen donation ability. These results are also supported by the representation of the molecular electrostatic potentials maps. The prediction of the cyclooxygenase inhibitory activity of the proposed QSAR equations is analysed using the multilineal (MLR) method. Finally, the differences in biological activity are examined by analysing the binding interactions of active compounds in the pocket site of human COX-2 enzyme structure derived from crystallographic X -ray data. [source] Prediction of Tyrosinase Inhibition Activity Using Atom-Based Bilinear IndicesCHEMMEDCHEM, Issue 4 2007Yovani Marrero-Ponce Prof. Abstract A set of novel atom-based molecular fingerprints is proposed based on a bilinear map similar to that defined in linear algebra. These molecular descriptors (MDs) are proposed as a new means of molecular parametrization easily calculated from 2D molecular information. The nonstochastic and stochastic molecular indices match molecular structure provided by molecular topology by using the kth nonstochastic and stochastic graph-theoretical electronic-density matrices, Mk and Sk, respectively. Thus, the kth nonstochastic and stochastic bilinear indices are calculated using Mk and Sk as matrix operators of bilinear transformations. Chemical information is coded by using different pair combinations of atomic weightings (mass, polarizability, vdW volume, and electronegativity). The results of QSAR studies of tyrosinase inhibitors using the new MDs and linear discriminant analysis (LDA) demonstrate the ability of the bilinear indices in testing biological properties. A database of 246 structurally diverse tyrosinase inhibitors was assembled. An inactive set of 412 drugs with other clinical uses was used; both active and inactive sets were processed by hierarchical and partitional cluster analyses to design training and predicting sets. Twelve LDA-based QSAR models were obtained, the first six using the nonstochastic total and local bilinear indices and the last six with the stochastic MDs. The discriminant models were applied; globally good classifications of 99.58 and 89.96,% were observed for the best nonstochastic and stochastic bilinear indices models in the training set along with high Matthews correlation coefficients (C) of 0.99 and 0.79, respectively, in the learning set. External prediction sets used to validate the models obtained were correctly classified, with accuracies of 100 and 87.78,%, respectively, yielding C values of 1.00 and 0.73. This subset contains 180 active and inactive compounds not considered to fit the models. A simulated virtual screen demonstrated this approach in searching tyrosinase inhibitors from compounds never considered in either training or predicting series. These fitted models permitted the selection of new cycloartane compounds isolated from herbal plants as new tyrosinase inhibitors. A good correspondence between theoretical and experimental inhibitory effects on tyrosinase was observed; compound CA6 (IC50=1.32,,M) showed higher activity than the reference compounds kojic acid (IC50=16.67,,M) and L -mimosine (IC50=3.68,,M). [source] | ||||||||||