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 toxicities of 34 benzonitriles to Tetrahymena pyriformis have been measured. Structure-activity relationships indicate that for these compounds different mechanisms of toxic action are taking place dependent on the nature of the substituent. Benzonitrile itself, some halogenated and the toluene derivatives model as non-polar narcotics; more polar substituents ...

Abstract: We propose interspecies quantitative structure–activity–activity relationships (QSAARs), that is, QSARs with descriptors, to estimate species-specific acute aquatic toxicity. Using training datasets consisting of more than 100 aromatic amines and phenols, we found that the descriptors that predicted acute toxicities to fish (Oryzias latipes) and algae were ...

Abstract: We present the results of an investigation into the use of a probabilistic neural network (PNN) based methodology to model the 48-60-h ICG50 (inhibitory concentration for population growth) sublethal toxicity to the ciliate Tetrahymena pyriformis. The information fed into the neural network is solely based on simple molecular descriptors as can be derived from ...

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: Human intestinal absorption is a key property for orally administered drugs and is dependent on pH. This study focuses on neutral and amphoteric compounds and their membrane permeabilities across the range of pH values found in the human intestine. The membrane permeability values for 15 neutral and 60 amphoteric compounds at pH 3, 5, 7.4 and 9 were measured ...

Abstract: The in silico modelling of bio-concentration factor (BCF) is of considerable interest in environmental sciences, because it is an accepted indicator for the accumulation potential of chemicals in organisms. Numerous QSAR models have been developed for the BCF, and the majority utilize the octanol/water partition coefficient (logP) to account for the penetration ...

Abstract: The aim of this investigation was to develop a strategy for the formulation of a valid ecotoxicological-based QSAR while, at the same time, minimizing the required number of toxicological data points. Two chemical selection approaches-distance-based optimality and K Nearest Neighbor (KNN), were used to examine the impact of the number of compounds used in the ...

Abstract: The relative toxicity (log IGC-1(50)) of 54 selected alkanones, both aliphatic and aromatic, as well as, alkenones and alkynones was evaluated in the static Tetrahymena pyriformis population growth assay. Excess toxicity, an indicator of bioreactivity, was associated only with the alpha-beta unsaturated alkenones and alkynones. Moreover, the alkynones were ...

Abstract: Using toxicity data for 30 aliphatic polarized alpha,beta-unsaturated derivatives of esters, aldehydes, and ketones, a series of six structure-toxicity relationships were evaluated. The structure feature of all assessed compounds, an acetylenic or olefinic moiety conjugated to a carbonyl group, is inherently electrophilic and conveys the capacity to exhibit ...