1. College of Pharmacy and Biological Engineering Chengdu University Chengdu 610106 P. R. China
2. Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province Sichuan Industrial Institute of Antibiotics Chengdu University Chengdu 610052 P. R. China
3. Institut für Organische und Biomolekulare Chemie Georg-August Universität Tammannstraße 2 37077 Göttingen Germany
4. Laboratoire d'Innovation Moléculaire et Applications (UMR CNRS 7042) Université de Strasbourg/Université de Haute Alsace, ECPM 25 Rue Becquerel 67087 Strasbourg France
5. Department of Chemistry University of Pavia Viale Taramelli, 10 27100 Pavia Italy