Structure—activity relationships for chloro‐ and nitrophenol toxicity in the pollen tube growth test

Abstract

Abstract-Acute toxicity of 10 chlorophenols and 10 nitrophenols with identical substitution patterns is analyzed with the pollen tube growth (PTG) test. Concentration values of 50% growth inhibition (IC50) between 0.1 and 300 mg/L indicate that the absolute sensitivity of this alternative biotest is comparable to conventional aquatic test systems. Analysis of quantitative structure-activity relationships using lipophilicity (log K ow ), acidity (pK a ), and quantum chemical parameters to model intrinsic acidity, solvation interactions, and nucleophilicity reveals substantial differences between the intraseries trends of log IC50. With chlorophenols, a narcotictype relationship is derived, which, however, shows marked differences in slope and intercept when compared to reference regression equations for polar narcosis. Regression analysis of nitrophenol toxicity suggests interpretation in terms of two modes of action: oxidative uncoupling activity is associated with a pK a window from 3.8 to 8.5, and more acidic congeners with diortho-substitution show a transition from uncoupling to a narcotic mode of action with decreasing pK a and log K ow . Model calculations for phenol nucleophilicity suggest that differences in the phenol readiness for glucuronic acid conjugation as a major phase-II detoxication pathway have no direct influence on acute PTG toxicity of the compounds.

pH‐Dependence and QSAR analysis of the toxicity of phenols and anilines to Daphnia magna

“…values are unrealistic i.e., much too high compared to toxicity data for these compounds in other species Ž . Cronin and Schultz, 1996;Schuurmann et al, 1996 . Iẗc an concluded that for the phenols at least, toxicity is not attributable solely to the non-ionized form, but also Ž .…”

“…Other workers have included a consideration of p K directly in the a QSAR for the prediction of the toxicity of phenols ŽBalaz et al, 1996;Pirselova et al, 1996;Kishino andˇˇ´. Kobayashi, 1996a;1996b;Schuurmann et al, 1996 .Ž . Cronin and Schultz 1996 reported a QSAR for the prediction of the toxicity of 120 phenols with log P and E as significant parameters.…”

“…They represent a ubiquitous component of the environment. As such, their toxicological properties have often been Ž assessed Balaz et al, 1996;Pirselova et al, 1996;ˇˇĆ ronin and Schultz, 1996;Kishino and Kobayashi, 1996a;1996b;Schuurmann et al, 1996;Schuurmann,¨¨. 1998 .…”

Mode of Action Assignment of Chemicals Using Toxicogenomics: A Case Study with Oxidative Uncouplers

“…To this end, two aniline compounds and PCP were included which are suggested to have a polar narcotic MoA, as well as ethylenglycol, which has a narcotic MoA. Structure-based MoA assignments generate equivocal results concerning the separation between polar narcosis and uncoupling (Schüürmann et al, 1996), with some studies classifying the anilines and PCP as uncouplers, while other studies classifying them as polar narcotics (Russom et al, 1997;Schüürmann et al, 1997;Argese et al, 2001;Spycher et al, 2008a;Janssens et al, 2011;Dom et al, 2012). Since these test chemicals are not unequivocally classified as uncouplers, the TMRM assay could not be used for the selection of equipotent test concentrations.…”

A new strategy for the sensitive electrochemical determination of nitrophenol isomers using β-cyclodextrin derivative-functionalized silicon carbide

“…4,5 It is well-known that the isomers of nitrophenol are serious environmental pollutants due to their potential toxicity (carcinogen, teratogenic and mutagenic) to human beings, animals, and plants even at a very low concentration. [6][7][8] The harmful effects of NP on humans include headache, fever, breathing trouble, and even death at high levels of exposure. 9 In addition, the NPs are readily accumulated in organisms and are hard to naturally degrade because of the high structure stability.…”