title: Quantitative structure-activity relationships for the inhibition toxicity to root elongation of Cucumis sativus of selected phenols and interspecies correlation with Tetrahymena pyriformis.
abstract: 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 (logKow) and energy of the lowest unoccupied orbital (E(lumo)) was derived (IRC50 = 0.77 log Kow - 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 logKow, E(lumo) and Qmax, the most negative net atomic charge, was developed (IRC50 = 0.65 logKow - 0.72E(lumo) + 0.23Qmax + 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-d 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.
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, The School of Environment, Nanjing University, People's Republic of China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Wang
authors.forename: Cheng
authors.initials: C
authors.lastname: Sun
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Liansheng
authors.initials: L
authors.lastname: Wang
mesh_terms: D000818:Animals; D028462:Cucumis / Q000254:growth & development*; D004353:Drug Evaluation, Preclinical / Q000379:methods; D010636:Phenols / Q000633:toxicity*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development; D013329:Structure-Activity Relationship; D013768:Tetrahymena; D018675:Toxicity Tests
chemical_list: D010636:Phenols