Algal growth inhibition of Chlorella pyrenoidosa by polar narcotic pollutants: toxic cell concentrations and QSAR modeling

The effects of 11 polar narcotic pollutants (phenols, nitrobenzenes and ani lines) on the algae Chlorella pyrenoidosa have been investigated in 72 h po pulation growth inhibition tests. The lowest observed effect concentration and no-observed effect concentrations were determined. The partial effect c oncentrations were estimated (EC10 and EC50) by the Weibull function, and n o-effect concentrations were determined by using the DEBTOX program. In add ition, for four of the chemicals, the internal cell concentrations yielding 10 and 50% growth inhibition were estimated from internal concentration-re sponse curves, The toxic cell concentrations vary from 0.1 to 1.6 and from 0.5 to 17 mmol kg(-1), for 10 and 50% inhibition, respectively. These value s are in agreement with reported data for Selenastrum capricornutum (0.7-2. 3 and 2-14 mmol kg(-1), respectively). Finally, the determined (no-)effect concentrations have been used to construct quantitative structure-activity relationship models using hydrophobicity and hydrogen bonding capacity desc riptors. The models indicate that toxicity increases with hydrophobicity, g ood hydrogen bonding donor capacity, and low hydrogen bonding acceptor capa city. The models can be interpreted based on the composition of biomembrane s, which are supposed to be the target of narcotic pollutants. (C) 1999 Els evier Science B.V. All rights reserved.