1. 8.2 Pharmaceutical and Medicinal Chemistry, Saarland University, P.O. Box 15 11 50, D-66041 Saarbruecken, Germany, Max Planck Institute for Informatics, Stuhlsatzenhausweg 85, D-66123 Saarbruecken, Germany, and Pharmacelsus CRO, Science Park 2, D-66123 Saarbruecken, Germany