Evaluation And Quantitative Structure-Activity Relationships Of Joint Toxicity Of Substituted Aromatic Compounds And Heavy Metals To Photobacterium Phosphoreum

The single toxicity of 9 substituted phenols and 11 nitro-substituted aromatic compounds to Phtobacterium phosphoreum were determined respectively. It shows that the toxicity is related to group variety, the number of group and their substitutive positions.On the determination of single toxicity of heavy metals, the joint toxicity of binary mixtures of organic pollutants and heavy metals (cadmium/lead and 9 substituted phenols in different cadmium/lead concentrations of 0.2 EC50, 0.5 EC50 and 0.8 EC50; copper/zinc and 11 nitro-substituted aromatic compounds in different copper/zinc concentrations of 0.2 EC50, 0.5 EC50 and 0.8 EC50) were measured. The joint toxicity was evaluated by Toxic Unit (TU) and Additive Index (AI) methods. On the theory of quantitative structure-activity relationship (QSAR), QSAR models were developed to study the joint toxicity of organic pollutants and heavy metals.The result of joint toxicity of cadmium (Cd) and 9 substituted phenols to Phtobacterium phosphoreum indicated that the joint toxicity was mainly simple addition or close to simple addition. QSAR equations were built from the joint toxicity and molecular structural descriptors of substituted phenols in the different Cd concentrations. It was shown that the joint toxicity in different Cd concentrations was related to the same descriptors, the logarithm of n-octanol/water partition coefficient (lgP) and the heat of formation (â–³Hf).The result of joint toxicity of lead (Pb) and 9 substituted phenols to Phtobacterium phosphoreum was showed as following. In the Pb concentration of 0.2 EC50, the binary joint effects of Pb and substituted phenols were antagonism. In the Pb concentration of 0.5 EC50, the binary joint effects of Pb and substituted phenols were related to the position of substituted groups of substituted phenols. The joint effects of Pb and ortho-substituted phenols were mainly antagonism. The joint effect of Pb and meta-substituted phenol (m-introphenol) is synergism. Whereas the joint effects of Pb and para-substituted phenols were mainly close to additive action. In the Pb concentration of 0.8 EC50, the binary joint effects of Pb and substituted phenols were synergism. The QSAR equations were built from the joint toxicity of substituted phenols in the different Pb concentrations of 0.2 EC50, 0.5 EC50 and 0.8 EC50. It shows that when Pb was set in different concentrations, the joint toxicity of substituted phenols is related to different physical-chemical parameters. In the low Pb concentrations, the joint toxicity is related to water solubility parameter (WS) and the third order molecular connectivity index (3X). In the medium Pb concentration, the joint toxicity is related to solute excess molar refractivity (E) and ionization constant (pKa). In the high Pb concentration, the joint toxicity is related to dipolarity/polarizability parameter (S). The result of joint toxicity of copper (Cu) and 11 nitro-substituted aromatic compounds to Phtobacterium phosphoreum was showed as following. In the Cu concentration of 0.2 EC50, the binary joint effects of Cu and nitro-substituted aromatic compounds were mainly simple addition. In this low Cu concentration, the joint toxicity is positively related to Connolly Solvent-Excluded Volume (CSEV) and (Polarity/Polarizability (S) of a molecular. In the Cu concentration of 0.5 EC50, simple addition, antagonism and synergism all existed in mixtures of Cu and 11 nitro-substituted aromatic compounds. In the Cu concentration of 0.8 EC50, the binary joint effects were mainly antagonism, meanwhile some were simple addition. In the medium and high Cu concentrations, the joint toxicity is positively related to Connolly Accessible Area (CAA) of a molecular.The result of joint toxicity of zinc (Zn) and 11 nitro-substituted aromatic compounds to Phtobacterium phosphoreum was showed as following. In the Zn concentration of 0.2 EC50, the binary joint effects of Zn and nitro-substituted aromatic compounds were mainly (about 82%) antagonism and simple addition (close to antagonism). In this low Zn concentration, the joint toxicity is positively related to Connolly Accessible Area (CAA) and Overall or Effective Hydrogen Bond Acidity (A) of a molecular. In the Zn concentration of 0.5 EC50, the binary joint effects of Zn and nitro-substituted aromatic compounds were mainly (about 91%) antagonism and simple addition. The joint toxicity of Zn and p-nitrobenzoic acid was an exception, which showed synergism. In the medium Zn concentration, the joint toxicity is related to ovality (Ov) and total energy (TE) of a molecular. In the Zn concentration of 0.8 EC50, the binary joint effects were antagonism (45%) and simple addition (55%). In the high Zn concentration, the joint toxicity is positively related to the second order molecular connectivity index (2X)...