Quantitative Structure−Activity Relationships for the Aquatic Toxicity of Polar and Nonpolar Narcotic Pollutants
Eñaut Urrestarazu Ramos, Wouter H. J. Vaes, Henk J. M. Verhaar, Joop L. M. Hermens · Journal of Chemical Information and Computer Sciences · 1998
QSARs were developed for the acute toxicity of narcotic pollutants (nonpolar and polar) to the water flea ( Daphnia magna ), the guppy ( Poecilia reticulata ), and the pond snail ( Lymnaea stagnalis ) using hydrophobicity ( log K OW ) and hydrogen bonding capacity descriptors ( Q -, Q +, ε HOMO, ε LUMO ). Toxicity increases with increasing hydrophobicity and to a minor extent with decreasing LUMO energies and increasing absolute charges in the molecule. The models are rationalized by taking into account the composition of biomembranes, into which chemicals must partition for displaying narcosis. The similarity of these results with models for the membrane/water partition coefficients supports the hypothesis that the toxicity of narcotics is directly related to the accumulation in biological membranes. The results indicate that baseline toxicity based on log K OW should be redefined for chemicals for which log K OW is not a good surrogate for partitioning into biological membranes.