1. Food Chemistry and Toxicology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76131 Karlsruhe, Germany
2. Department of Chemistry, The University of Western Ontario (UWO), London, Ontario, N6A 5B7, Canada. Fax: +1-519-661-3022; Tel: +1-519-661-3821