1. Faculty of Pharmaceutical Sciences, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan
2. National Institute of Health Sciences, Kamiyoga 1-18-1, Setagaya-ku, Tokyo 158-8501, Japan
3. Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
4. Institut de Chimie de la Substances Naturelles, Centre Nationale de la Recherches Scientifique, 91198, Gif-sur Yvette, Cedex, France