1. Pharmaceutical and Medicinal Chemistry, Saarland University, P.O. Box 151150, D-66041 Saarbrücken, Germany
2. Department of Internal Medicine I, University of Frankfurt, Theodor-Stern-Kai 7, D-60590 Frankfurt a.M., Germany
3. Department of Organic Chemistry, Saarland University, P.O. Box 151150, D-66041 Saarbrücken, Germany