Toxicity Of Organic Pollutants To Tetrahymena Pyriformis And Structure-Activity Relationship

Fish, Daphnia Magna, Chlorophyta, freshwater photobacteria of marineorganisms, enzyme and cells are commonly used in the biological toxicology experiment. Tetrahymena pyriformis is one of the most widely used basic biological models in a variety of biological toxicology experiment. In this paper, toxicity data of 970 kinds of organic pollutants, inhibition during the growth of Tetrahymena pyriformis are collected from literature. The dataset containing 325 aliphatic hydrocarbons and 645 aromatic hydrocarbons was divided into 55 groups based on the structural features of functional groups. After the QSAR analysis between the toxicity and the hydrophobicity, polarity and ionization parameters of the chemical compound, following conclusions were obtained: First, there is a good linear relationship between toxicity and hydrophobicity for compounds of polar narcotics and non-polar narcotics. A QSAR model has been developed between octanol/water partition coefficient and tozxicity for polar narcotics and non-polar narcotics. Second, the toxicity of polar narcotics compounds is higher than non-polar narcotics ones, but there is uniform standard to distinct them. We suggested that the high hydrophobic polar narcotics may regard as non-polar narcotics compounds, because the polarity of compounds is decided not only by the substituent group, but also the total hydrophobicity of the compounds. Based on this point of view, we introduced the molecular polar parameter S, and set a regression equation between the octanol/water partition ratio (logP) and polarity parameter (S) for the two types of compound's toxicity data. Third, biological toxicity of ionic compounds increases while the ionic degree increases. However, when the ionization achieves the certain extent, its toxicity reduces instead. We suggest that this is due to the reduce of uptake. Based on this theory, we study the influence of ionization to the toxicity and set a regression equation between the toxicity of ionic organic compounds and the ionization rate. Forth, We set a QSAR model (n=822,R2=0.83) betwen the toxicity and the hydrophobicity, polarity, and ionization of compounds. This model can successfully estimate the toxicity of non-polar narcotics, polar narcotics, ionization and reactive compounds. The QSAR model constructed in this paper uses small number of parameters and has a high transparency.