Quantitative structure-activity relationships of nitroaromatic compounds to four aquatic organisms

Quantitative structure-activity relationships of 26 nitroaromatic compounds to guppy (Poecilia reticulata), carp (Cyprinus carpio), Scenedesmus obliguus, Daphnia carinata were studied based on equations we established. Results showed that observed toxicity of chemicals could be estimated by the parameters of halfwave reduction potential (E1/2) and bioconcentration factor (BCF). The toxicity data of nitroaromatic compounds to four aquatic organisms were estimated by these parameters. Compared with octanol/water partition coefficient method, the LC50 values predicted by the two parameters are close to observed LC50 values. Regression results also showed that the highest occupied molecular orbital energy (EHOMO), the lowest unoccupied molecular orbital energy (ELUMO) and octanol/water partition coefficient (KOW) were ideal parameters instead of the reaction equilibrium constant of target molecule-organic chemical in target cells (K) and bioconcentration factor. Relationships between the toxicity data of guppy, carp, Scenedesmus obliguus, Daphnia carinata and the parameters of EHOMO, ELUMO and KOW were analyzed. Predicted and observed LC50 values are in good agreement. The observed toxicity data of 2,4-dinitrotoluene and 2,6-dinitrotoluene may be lower than the expected toxicity data because the photolysis of the two chemicals is rapid during the course of experiments.