PARENT SESSION

1F - QSAR
Hall 13
8:30 AM - 12:30 PM, Tuesday, 29 April 2003
Chair: Schüürmann, G.¹, ¹
Co-chair: Verhaar, H.J.M.², Cronin, M.³, ^{2 3}

(TU13/4) A Structurally-Interpretable Approch to QSAR Models for Eco-toxicological Variables.

Estrada, Ernesto¹, Uriarte, Eugenio², ¹ SEAC, Unilever R&D, Colworth House, Sharnbrook, Beds, UK² Faculty of Pharmacy, University of Santiago de Compostela, Santiago de Compostela, A Coruna, Spain

ABSTRACT- An approach based on the use of the bond matrix representation of molecules is used to derive QSAR models for several eco-toxicological variables. The approach uses descriptors based on hydrophobicity, polar surface, van der Waals area, Gasteiger-Marsilli atomic charges, molar refractivity, bond distances and bond dipoles as bond weights. These contributions are embodied into descriptors that are expressed as linear combinations of the different structural fragments of molecules. This approach is named the TOPological Sub-structural MOlecular DEscriptors (TOPS-MODE). The final objective of it is to find the structural contributions of the different parts of a molecule to a biological or toxicological activity. Here we apply this approach to several eco-toxicological endpoints. They include toxicity of aromatic compounds to T. pyriformis and the toxicity of several classes of chemicals to P. reticulata. Details of the possible toxicophores identified by the TOPS-MODE approach for the toxicity of pesticides to P. reticulata as well as of aromatic nitro compounds to T. pyriformis are analysed. Some general conclusions on the possible applications of this approach in predicting and interpreting QSAR models for eco-toxicological endpoints are obtained.

Key words: TOPS-MODE, QSAR, pesticides, aromatic compounds