The evaluation of topological pharmacophores by heuristic approach.

A simple approach to evaluate logical pharmacophores on the base of topological features is described. It is based on considerations of the relative frequencies of structural features within different classes of activity. Shannon's entropy is used in the case of more than two classes. To obtain a pharmacophore a stepwise interactive procedure is performed. The algorithm is applied to fungicidal carboxamides and beta-adrenergic phenethylamine agonists and antagonists. In both cases meaningful pharmacophores could be obtained.