Modelling toxicity using molecular quantum similarity measures

In this work, a general procedure for the application of Molecular Quantum Similarity Measures (MQSM) into the Quantitative Structure-Toxicity Relationships (QSTR) field is presented. The methodology is presented from its theoretical background, beginning with the formulation of MQSM and the role of density functions. Other topics, like molecular modelling, electronic density fitting, similarity scaling and molecular superposition are also analysed. The theoretical part is complemented with three different application examples dealing with acute aquatic toxicity related to different fish species. The molecular sets are constituted by different kinds of benzene derivatives. Acceptable correlations are obtained for the aquatic toxicity using quantum similarity derived descriptors, allowing a fairly confident classification of the studied compounds according to their toxicity level.