QSAR Study Of Halophenols And Nitroaromatic Compounds Toxicity To Tetrahymena Pyriformis

Organic pollutants in water environment have constructed hazards on environment. The trace toxic organic pollutants have been arouse widely attentions since in the process of migration and transformation, the organic pollutants which concentration are ultimately up to the exposure concentration will threat to aquatic life, human and ecological system. Hence, in this paper, the ecological risk management techniques on the water environment at home and abroad were reviewed firstly, and secondly, using the data in literatures and the calculated molecular structure parameters of corresponding pollutants, quantitative structure-activity relationship (QSAR) method was used to value the toxic effect on the environmental life and the internal toxic mechanisms of halogenated phenols and nitroaromatic compounds.A total of 73 halogenated phenols (16 fluorophenols,21 bromophenols and 36 chlorophenols) and 42 nitroaromatic compounds were selected as target pollutants. The QSAR models were set up with some selected parameters calculated by Chem 3D Ultra 7.0 software with PM3 and AM1 methods and some toxicity datas to Tetrahymena pyriformis collected from literatures to identify the impacts and toxicity mechanism of halogenated phenols and nitroaromatics. In this study, partial least squares regression(PLS) method was used to solve the problems, which the traditional multiple linear regression can not be solved, such as the multicollinearity and the excessive use of molecular structure parameters.The quantitative structure activity relationship(QSAR) of 16 fluorophenols,21 bromophenols and 36 chlorophenols toxicity to Tetrahymena pyriformis were set up with 19 quantum-chemical and physical-chemical parameters calculated by Chem 3D Ultra 7.0 software PM3 method combined with the toxicity data selected from literature, by the use of partial least squares(PLS) method. QSAR models with high correlation coefficients were obtained and the internal cross validation test results showed the obtained models had high precision and good prediction capability.The results of PLS analysis indicated that the acute toxicity of fluorophenols and chlorophenols to Tetrahymena pyriformis is the main result of toxic reaction, while the acute toxicity of bromophenols to Tetrahymena pyriformis is the main result of polarity anesthetic effect. There was a remarkable negative correlation between the acute toxicity of fluorophenols and ELUMO,ΔE,and ET respectively, and a significant positive correlation was observed between the acute toxicity fluorophenols and QH+,QO-,CAA,CSV, respectively. There was a remarkable negative correlation between the acute toxicity of bromophenols and ELUMO,ΔE,QO- respectively. A significant positive correlation was observed between the acute toxicity bromophenols and logKow,ΔHf,CMA,QH+, respectively. In addition, there was a remarkable negative correlation between the acute toxicity of chlorophenols and ELUMO,QH+,QC(?)-,CCR,QO- respectively. A significant positive correlation was observed between the acute toxicity chlorophenols and MW,a,EE, respectively.The toxicity of 42 nitroaromatics from literature, combined with 20 quantum-chemical and physical-chemical parameters calculated by Chem 3D Ultra 7.0 software AM1 method, the quantitative structure activity relationship(QSAR) of Tetrahymena pyriformis were study via partial least squares(PLS) method when a 2:1 ratio was selected for training set and testing set. Optimized models with high correlation coefficients were obtained and both the internal cross validation test and external validation test results showed the obtained models had high precision and good prediction capability (R2=0.946, Q2(cum)=0.921, P=5.5×10-18, F=453.53, SD=0.171). The obtained models are considered to be superior to the former reported models. Seven parameters, including ELUMO,a,QNO2-,ET,MW, CSV and MR, had important contributions to the toxic effects of nitroaromatics. There was a remarkable negative correlation between the acute toxicity and ELUMO,ET andΔE respectively, and a significant positive correlation was observed between the acute toxicity and a,QNO2-,QO-,ΔHf,MW,CSV and MR, respectively.