1. Institut de Pharmacognosie et Phytochimie, Université de Lausanne, BEP, CH-1015 Lausanne, Switzerland, Institut de Cristallographie, Université de Lausanne, BSP, CH-1015 Lausanne, Switzerland, Natural Products Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand, and Department of Physics, Faculty of Science and Technology, Thammasart University, Patumtani 12121, Thailand