Automatic log P estimation based on combined additive modeling methods.

A program for the automatic estimation of the logarithm of the partition coefficient between 1-octanol and water phases (log P) has been developed as a component of a system entitled CHEMICALC (Combined Handling of Estimation Methods Intended for Completely Automated Log P Calculation). Log P values are calculated based on additive group contributions to log P. Three sets of groups are defined, and their contributions have been derived from the experimental log P values of 1465 molecules. The system divides a structural formula of a compound of interest into the groups whose increments are provided and then calculates its log P value. All processing after structure input is fully automated. This system has been tested for predicting the log P values of 1686 compounds. The accuracy is sufficient for many practical purposes.