1. Department of Pharmacy National University of Singapore 18 Science Dr 4 Singapore 117543 Singapore
2. Department of Medicinal Chemistry University of Utah Salt Lake City UT 84112 USA
3. Laboratory of Chemical Biology of Natural Products Graduate School of Bioagricultural Sciences Nagoya University, Furo-cho, Chikusa Nagoya 464-8601 Japan
4. Institut Pasteur Collection des Cyanobactéries Département de Microbiologie 75015 Paris France