A quantitative structure-activity relationship between partition coefficients and the acute toxicity of naphthalene derivatives in Artemia salina nauplii

The 1-octanol/water partition coefficient has been used frequently as a rapid predictor of organic pollutant bioconcentration potential in aquatic life. Harmful effects of aromatic compounds have been related to partition coefficients in a meaningful way. Acute toxicity tests were conducted by exposing 30-h posthatch Artemia salina larvae cultured at 19°C in artificial sea water to naphthalene, naphthalene derivatives, and other nonrelated chemicals for 24 h to determine immobilization concentrations (IC₅₀). The IC₅₀ value for each chemical was used to derive a quantitative structure-activity relationship (QSAR) which included the partition coefficient as the only parameter of molecular structure. A linear correlation resulted for all chemicals tested using Artemia:

$\text{log}\text{1}\text{IC}{}_{50}\text{=1.57(plusm 0.60)+0.88(plusm 0.12)×}\text{log}\text{P}$

where n = 11, r² = 0.968, and s = 0.226. The hydrophobic nature of the chemicals appeared to be the most important factor producing larval immobilization because the naphthalene congener set was not collinear with electronic and steric physicochemical properties. The IC₅₀ values were also correlated with the molecular weight and boiling point of each chemical, but a significant increase in the regression variance occurred in comparison to log P. The naphthalene QSAR was a good predictor of acute toxicity in Artemia nauplii.