1. Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy (GRIP), Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands, School of Pharmacy, Institut Teknologi Bandung (ITB), Jl. Ganesha 10, Bandung, Indonesia, and Institut für Organische Chemie, Universität Hamburg, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany