Acute toxicity of eight phenols towards ten biological test systems is
characterized with principal component analysis and partial least-squ
ares regression in terms of underlying modes of action and associated
compound properties. The test battery consists of nine different speci
es: three fish, one waterflea, one ciliate, one marine bacterium in tw
o different assays, two fish cell lines and one plant pollen. The comp
ound set contains phenol, five chlorophenols and two nitrophenols, rep
resenting polar narcotics and uncouplers of oxidative phosphorylation.
Lipophilicity (log K-ow) and acidity (pK(a)) as well as respective bi
linear decompositions in quantum chemical parameters are used as molec
ular descriptors. The results reveal substantial differences in specif
ic sensitivity of the test systems for uncoupling activity. Furthermor
e, pentachlorophenol (as a classical uncoupler) exerts no significant
excess toxicity over polar narcosis with any of the ten endpoints, and
4-nitrophenol apparently acts as uncoupler with most of the non-fish
test species including procaryotic cells. The discussion includes alte
rnative hypotheses about the underlying mechanism of uncoupling activi
ty. (C) 1997 Elsevier Science B.V.