Abstract: Toxicity to the ciliate Tetrahymena pyriformis (log(IGC(50)(-1))) for 39 halogen-substituted alkanes, alkanols, and alkanitriles were obtained experimentally. Log(IGC(50)(-1)) along with the hydrophobic term, logK(ow) (1-octanol/water partition coefficient) and the electrophilic parameter, E(lumo) (the energy of the lowest unoccupied molecular orbital) were ...

Abstract: A set of 221 phenols, for which toxicity data to the ciliate Tetrahymena pyriformis were available, was subjected to stepwise linear discriminant analysis (LDA) in order to classify their toxic mechanisms of action. The compounds were a priori grouped into the following four mechanisms according to structural rules: polar narcotics, weak acid respiratory ...

Abstract: Reactive toxicity encompasses important endpoints such as skin and respiratory sensitization, hepatotoxicity and elevated acute aquatic toxicity. These adverse effects are initiated by, among others, electrophilic chemicals and those transformed into electrophiles; i.e. non-reactive chemicals activated into reactive electrophilic species by either a biotransformation ...

Abstract: The toxicity data of 256 chemicals tested in both the 96-h Pimephales promelas mortality assay and the 2-d Tetrahymena pyriformis growth inhibition assay were evaluated using quantitative structure-activity relationships (QSARs). Each chemical was a priori assigned a mode of action of either narcoses or soft electrophilicity. Narcoses were separated into ...

Abstract: A recently introduced chemoassay has been used to determine second-order rate constants of the electrophile-nucleophile reaction of 15 α,β-unsaturated aldehydes with glutathione. The respective kGSH values vary for more than 3 orders of magnitude, and are within the range determined previously for 31 α,β-unsaturated ketones and esters. Structure-reactivity ...

Abstract: The relative biological response (log BR) for each of 30 select substituted phenols and anilines was evaluated using the 48-h Tetrahymena pyriformis population growth test system. Simple linear regression analysis of log BR versus log Kow (1-octanol/water partition coefficient) was used to formulate a quantitative structure-activity relationship (QSAR). The ...

Abstract: Quantitative structure-activity relationships (QSARs) for the toxicity of 200 phenols to the ciliated protozoan Tetrahymena pyriformis, and the validation of the QSARs using a test set of a further 50 compounds, are reported. The phenols are structurally heterogeneous and represent a variety of mechanisms of toxic action including polar narcosis, weak acid ...

Abstract: Toxicity data for the 50% growth inhibitory concentration against Tetrahymena pyriformis (log (IGC50(-1))) for 42 alkyl- and halogen-substituted nitro- and dinitrobenzenes were obtained experimentally. Log (IGC50(-1)) along with the hydrophobicity, the logarithm of the 1-octanol/water partition coefficient (log Kow), and the molecular orbital properties, the ...

Abstract: The purpose of this study was to develop quantitative structure-activity relationships (QSARs) for the toxicity of 268 aromatic compounds in the Tetrahymena pyriformis growth inhibition assay. The QSARs were developed using the response-surface (or two-parameter) approach, which was also modified using linear free-energy parameters to account for outliers. ...

Abstract: A QSAR analysis has been carried out of the toxicity of 47 mono-substituted nitrobenzenes to the aquatic ciliate Tetrahymena pyriformis. The single most important parameter was the logarithm of the apparent partition coefficient (logD) at pH 7.35. 2- and 3-derivatives yielded an excellent correlation of toxicity with log D, Swain-Lupton field parameter and ...