Ref ID : 6981
Xiaodong Wang, Cheng Sun, Yu Wang, and Liansheng Wang; Quantitative structure-activity relationships for the inhibition toxicity to root elongation of Cucumis sativus of selected phenols and interspecies correlation with Tetrahymena pyriformis. Chemosphere 46:153-161, 2002
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The comparative toxicities of selected phenols to higher plants Cucumis sativus were measured and the negative logarithm molar concentration of the root elongation median inhibition (IRC50) were derived. Quantitative structure-activity relationships (QSARs) were developed to explore the toxicity influencing factors and for predictive purpose. The toxicity data, fell into two classes: polar narcosis and bio-reactive. For polar narcotic phenols, a highly significant two-parameter QSAR based on 1-octanol/water partition coefficient (logK(ow)) and energy of the lowest unoccupied orbital (E(lumo)) was derived (IRC50=0.77 logK(ow)-0.39E(lumo)+2.36 n=22 (r2)=0.89). The five bio-reactive chemicals proved to show elevated toxicity due to their typical substructure involved diverse reactive mechanisms. In an effort to model all chemicals, a robust multiple-variable QSAR combining logK(ow), E(lumo) and Q(max), the most negative net atomic charge, was developed (IRC50=0.65logK(ow)-0.72E(lumo)+0.23Q(max)+2.81 n=27 (r2)=0.94), indicating that hydrophobicity, electrophilicity and hydrogen bond interaction contribute mainly to the phytotoxicity. The toxicological data was compared with Tetrahymena pyriformis 2-day population growth inhibition toxicity (IGC50) and excellent interspecies correlations were observed both for the polar narcotics and for five reactive chemicals (for polar narcotics: IRC50=0.95IGC50+1.07 n=16 (r2)=0.89; for bio-reactive chemicals: IRC50=0.98IGC50+2.19 n=5 (r2)=0.97; and for all: IRC50 =0.93IGC50+1.63 n=21 (r2)=0.87). This suggested that T. pyriformis toxicity could serve as a surrogate of C. sativus toxicity for phenols and interspecies correlation also could be established for reactive chemicals.