PREDICTION OF DISTRIBUTION COEFFICIENT FROM STRUCTURE .2. VALIDATION OF PROLOG-D, AN EXPERT-SYSTEM

Prolog D is a program that formalizes, in a controllable and reproduci ble manner, an algorithm developed to predict distribution coefficient s of ionizable compounds at a given pH and varying counterion concentr ations. Its predictive power has been evaluated with experimental log D values measured under standard conditions of buffers and ionic stren gth. Calculations were performed with the three different options for the estimation of partition coefficients (log P) implemented in the pr ogram. Considering the diversity of test compounds as well as the pres ent state of the art in log P and pK(a) predictions, Prolog D proved t o be very efficient and can be used as a tool to provide lipophilicity data. Prediction patterns and correlations with the observed data are of almost equal quality for all options, permitting acceptable result s for 80% of the data.