1. Medical Research Division, Korea Institute of Oriental Medicine, 1672 Yuseongdae-ro, Yuseong-gu, Daejeon 305-811, Republic of Korea
2. Department of Biochemistry and Molecular Biology, Michigan State University, 603 Wilson Road, East Lansing, MI 48824, USA
3. Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, MI 48824, USA