Abstract: The aim of this study was to evaluate a multivariate statistical model, utilising Partial Least Squares (PLS) analysis, for the prediction of the acute toxicity of aliphatic chemicals to the ciliate Tetrahymena pyriformis. A model was developed that was capable of making a prediction regardless the mechanism of toxic action. The toxicity of 476 compounds, ...

Abstract: The response-surface approach to QSARs attempts to model toxic potency of diverse groups of chemicals while avoiding problems associated with the identification of the mechanism of toxic action or specific chemical class often associated with other approaches. However, while hydrophobicity-dependent, simple regression QSARs derived for congeneric series of ...

Abstract: The aquatic toxicities (log(IGC50-1)) of 22 quinones were evaluated in the static Tetrahymena pyriformis population growth assay. A toxicity in excess of baseline was associated with each chemical eliciting a response. The ortho-quinones were the most toxic; internal quinones, with benzenoid substitution on both sides of the quinoid rings, were not toxic at ...

Abstract: Quantitative structure-activity relationships are developed for the toxicity of 166 varied phenol derivatives to the ciliate Tetrahymena pyriformis. A variety of physico-chemical descriptors were calculated but no significant relationship could be obtained for all 166 compounds. When certain chemical groups were omitted from the correlation however, notably ...

Abstract: A diverse set of 60 haloaliphatic compounds were evaluated for reactivity with cysteine thiol groups in the previously described RC(50) assay using glutathione (GSH) as a model nucleophile. Reactivity was quantified by the RC(50) value, the concentration of test compound that produced 50% reaction of the GSH thiol groups in 120 min. Under standard conditions, ...

Abstract: This paper presents a mechanistic analysis of aquatic toxicity data, quantified as pIGC(50) assessed in the 40 h Tetrahymena pyriformis population growth impairment assay, for 40 polyhydroxybenzene derivatives. The toxicity trends of these phenolic compounds have been shown to be consistent with mechanistic organic chemistry principles. Thus, it is shown that ...

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 response-plane has been developed with Tetrahymena pyriformis population growth impairment toxicity data [log 1/50% growth inhibitory concentration (IGC50)], the 1-octanol/water partition coefficient (log Kow), and the energy of the lowest unoccupied molecular orbital (Elumo). A statistically robust plane [log 1/IGC50 = 0.530 (log Kow) -0.890 (Elumo) -0.271, ...