1. Institute of Natural Products Chemistry, Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Caugiay, Hanoi, Vietnam, Institute of Ecology and Biological Resources, VAST, 18 Hoang Quoc Viet, Caugiay, Hanoi, Vietnam, College of Pharmacy, Chungnam National University, Daejeon 305-764, Korea, and Skeletal Diseases Genome Research Center, School of Medicine, Kyungpook National University, Daegu 700-412, Korea