1. Department of Chemistry and Pharmacy, Emil-Fischer-Center, University of Erlangen—Nuremberg, Schuhstrasse 19, 91052 Erlangen, Germany, Institute of Biochemistry, Emil-Fischer-Center, University of Erlangen—Nuremberg, Fahrstrasse 17, 91054 Erlangen, Germany, and Institute of Microbiology and Toxicology, Federal Research Centre for Nutrition and Food (Bundesforschungsanstalt für Ernährung und Lebensmittel), E.-C.-Baumann-Strasse 20, 95326 Kulmbach, Germany