1. Laboratory of Aquatic Natural Products Chemistry and Laboratory of Wood Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan, Suntory Institute for Bioorganic Research, Wakayamadai, Shimamoto-cho, Osaka 618-8503, Japan, and Zoological Museum of the University of Amsterdam, P.O. Box 94766, 1090 GT Amsterdam, The Netherlands