1. Department of Bioorganic Chemistry Leibniz Institute of Plant Biochemistry Weinberg 3 06120 Halle/Saale Germany
2. present address: Department of Biomolecular Systems Max-Planck Institute of Colloids and Interfaces Am Mühlenberg 1 14476 Potsdam Germany
3. Department of Pharmaceutical Biology Martin-Luther-University Halle-Wittenberg Institute of Pharmacy/Pharmacognosy Hoher Weg 8 06120 Halle Germany