Event-based criteria in GT-STAF information indices: theory, exploratory diversity analysis and QSPR applications

Abstract

Versatile event-based approaches for the definition of novel information theory-based indices (IFIs) are presented. An event in this context is the criterion followed in the “discovery” of molecular substructures, which in turn serve as basis for the construction of the generalized incidence and relations frequency matrices, Q and F, respectively. From the resultant F, Shannon's, mutual, conditional and joint entropy-based IFIs are computed. In previous reports, an event named connected subgraphs was presented. The present study is an extension of this notion, in which we introduce other events, namely: terminal paths, vertex path incidence, quantum subgraphs, walks of length k, Sach's subgraphs, MACCs, E-state and substructure fingerprints and, finally, Ghose and Crippen atom-types for hydrophobicity and refractivity. Moreover, we define magnitude-based IFIs, introducing the use of the magnitude criterion in the definition of mutual, conditional and joint entropy-based IFIs. We also discuss the use of information-theoretic parameters as a measure of the dissimilarity of codified structural information of molecules. Finally, a comparison of the statistics for QSPR models obtained with the proposed IFIs and DRAGON's molecular descriptors for two physicochemical properties log P and log K of 34 derivatives of 2-furylethylenes demonstrates similar to better predictive ability than the latter.

Keywords:

• event
• Shannon's, mutual
• conditional and joint entropy
• magnitude criterion
• GT-STAF
• TOMOCOMD-CARDD
• cluster analysis
• QSPR

Acknowledgements

Y. Marrero-Ponce thanks the ‘Estades Temporals per an Investigadors Convidats’ program for a fellowship to work at Valencia University in 2012. The authors acknowledge the partial financial support from Spanish Ministry of Science and Innovation (MICINN, project reference: SAF2009-10399). Finally, this work was also partially supported by VLIR (Vlaamse InterUniversitaire Raad, Flemish Interuniversity Council, Belgium) under the IUC Program VLIR-UCLV.