1. Division of Pharmacognosy and Natural Products Chemistry, Department of Pharmacy, University of Athens, Panepistimiopolis Zografou, GR-15771 Athens, Greece, X-ray Laboratory, NCSR DEMOKRITOS, Athens 15310, Greece, and Laboratoire de Pharmacognosie de l'Université René Descartes, UMR/CNRS 8638, Faculté de Pharmacie, 4 Avenue de l'Observatoire, F-75006 Paris, France