Is Experimental Data Quality the Limiting Factor in Predicting the Aqueous Solubility of Druglike Molecules?

D.S.P. is grateful for funding from the European Commission through a Marie Curie Intra-European Fellowship within the seventh European Community Framework Programme (FP7-PEOPLE-2010-IEF). D.S.P. thanks the University of Strathclyde for support through its Strategic Appointment and Investment Scheme. Computations were performed at the EPSRC funded ARCHIE-WeSt High Performance Computer (www.archie-west.ac.uk, EPSRC grant no. EP K0005861). J.B.O.M. thanks the Scottish Universities Life Sciences Alliance (SULSA) for financial support and EaStCHEM for access to the EaStCHEM Research Computing Facility. We report the results of testing quantitative structure-property relationships (QSPR) that were trained upon the same druglike molecules but two different sets of solubility data: (i) data extracted from several different sources from the published literature, for which the experimental uncertainty is estimated to be 0.6-0.7 log S units (referred to mol/L); (ii) data measured by a single accurate experimental method (CheqSol), for which experimental uncertainty is typically