Jaworska, J.S.; Hunter, R.S.; Gobble, J.R.; Schultz, T.W. Structure-Activity Relationships for Diesters: Aquatic Toxicity to Tetrahymena. In Quantitative Structure-Activity Relationships in Environmental Sciences; Chen, F.; Schüürmann, G., Eds.; SETAC Press; 1997.

Abstract

The modeling of aquatic toxic potency of 35 diesters tested using the static Tetrahymena pyriformis population growth inhibition assay has been investigated. Toxicity was correlated with a number of structural patterns. including the bond type at the carbon atom adjacent to the carbonyl group. The less toxic saturated and non-α,β-unsaturated diesters are believed to act by way of a narcotic-type mechanism. A hydrophobicity, log 1-octanol/water partition coefficient (log Kow) dependent structure-activity relationship. different from the relationship for baseline toxicity, was developed (log IGC50(-1) = 0.61 (log Kow) -1.25; n = 20, r2 = 0.892, s = 0.310, F = 148, Pr > F = 0.0001) for the saturated and non-α,β-unsaturated diesters. While the specific molecular mechanism is not always clear, the more toxic (α,β-unsaturated diesters are believed to act as soft electrophiles. An average acceptor superdelocalizability (S(n)(av)) dependent structure-activity relationship was developed (log IGC50(-1) = 98.72 (S(n)(av)) -23.79; n = 15, r2 = 0.861, s = 0.462, F = 80, Pr > F = 0.0001) for the (α,β-unsaturated diesters. Efforts to model the toxic potency of all tested diesters using log Kow and S(n)(av) as descriptors failed.