1. Natural
Products Research Institute, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea
2. Department
of Agricultural Biotechnology, College of Agriculture and Life Science, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-921, Republic of Korea
3. Department
of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0358, United States
4. College
of Pharmacy, Gachon University, 191 Hambakmoero, Yeonsu-gu, Incheon 406-799, Republic of Korea