1. Silver Biotechnology Research Center, Hallym University, Chunchon 200-702, South Korea
2. Natural Products Research Institute, Seoul National University, Seoul 110-460, South Korea
3. Natural Products Research Center, Korea Institute of Science and Technology, Seoul 136-791, South Korea
4. Division of Applied Sciences, Korea Institute of Science and Technology, Seoul 136-791, South Korea
5. Department of New Material Chemistry, Korea University, Chungnam 339-700, South Korea