1. Department of Chemistry, Biology, and Marine Science, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan, Okinawa Industrial Technology Center, 12-2 Suzaki, Gushikawa, Okinawa 904-2234, Japan, Research and Development Centre for Oceanology, LIPI, Jl. Pasir Putih 1, Ancol Timur, Jakarta 11048, Indonesia, and Antibiotics Laboratory, RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198, Japan