1. Natural Products Research Institute, College of Pharmacy, Seoul National University, 599 Gwanangno, Gwanak-gu, Seoul 151-742, Korea, School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang 110016, Peopleʼs Republic of China, Marine Natural Products Laboratory, Korea Ocean Research & Development Institute, Ansan P.O. Box 29, Seoul 425-600, Korea, and School of Agricultural Biotechnology, Seoul National University, San 56-1, Sillim, Gwanak, Seoul 151-921, Korea