Combined QSAR studies of inhibitor properties of O-phosphorylated oximes toward serine esterases involved in neurotoxicity, drug metabolism and Alzheimer's disease

Abstract

Oxime reactivation of serine esterases (EOHs) inhibited by organophosphorus (OP) compounds can produce O-phosphorylated oximes (POXs). Such oxime derivatives are of interest, because some of them can have greater anti-EOH potencies than the OP inhibitors from which they were derived. Accordingly, inhibitor properties of 58 POXs against four EOHs, along with pair-wise selectivities between them, have been analysed using different QSAR approaches. EOHs (with their abbreviations and consequences of inhibition in parentheses) comprised acetylcholinesterase (AChE: acute neurotoxicity; cognition enhancement), butyrylcholinesterase (BChE: inhibition of drug metabolism or stoichiometric scavenging of EOH inhibitors; cognition enhancement), carboxylesterase (CaE: inhibition of drug metabolism or stoichiometric scavenging of EOH inhibitors), and neuropathy target esterase (NTE: delayed neurotoxicity). QSAR techniques encompassed linear regression and backpropagation neural networks in conjunction with fragmental descriptors containing labelled atoms, Molecular Field Topology Analysis (MFTA), Comparative Molecular Similarity Index Analysis (CoMSIA), and molecular modelling. All methods provided mostly consistent and complementary information, and they revealed structural features controlling the ‘esterase profiles’, i.e. patterns of anti-EOH activities and selectivities of the compounds of interest. In addition, MFTA models were used to design a library of compounds having a cognition-enhancement esterase profile suitable for potential application to the treatment of Alzheimer's disease.

Keywords:

• anti-Alzheimer drugs
• comparative molecular similarity index analysis (CoMSIA)
• molecular field topology analysis (MFTA)
• phosphorylated oxime (POX)
• quantitative structure-activity relationships (QSAR)
• serine esterases

Acknowledgements

The authors gratefully acknowledge the support of this work by the Russian Foundation for Basic Research (RFBR, grants no. 11-03-00581 and 11-03-01174), Ministry of Education and Science of Russia (Federal Program ‘Scientists and Educators for Innovative Russia’ 2009–2013), and Russian Academy of Sciences (RAS).