1. Niigata College of Pharmacy, Kamishin'ei-cho, Niigata 950-2081, Japan, Faculty of Pharmaceutical Sciences, Fukuoka University, Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan, BBI-Biotech Research Laboratories, Perry Parkway, Gaithersburg, Maryland 20877, and Natural Products Laboratory, School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599