1. College of Pharmacy, Seoul National University, Seoul 151-742, Korea, College of Medicine, Chungbuk National University, Cheongju 361-763, Korea, Ulsan University Hospital, Ulsan 682-714, Korea, College of Medicine, Chung-Ang University, Seoul 156-756, Korea, and R&D Center, AMOREPACIFIC, Gyeonggi-do 446-729, Korea