1. Helmholtz Institute for Pharmaceutical Research Saarland, HIPS; Department for Drug Design and Optimization; Campus E8.1 66123 Saarbrücken Germany
2. Department of Biochemistry; Saarland University; Campus B2.2 66123 Saarbrücken Germany
3. Institute for Tuberculosis Research; College of Pharmacy; University of Illinois at Chicago; 833 S. Wood Street Chicago IL 60612-7231 USA
4. Department of Pharmacy; Pharmaceutical and Medicinal Chemistry; Saarland University; Campus C2.3 66123 Saarbrücken Germany