1. College of Pharmacy, Pusan National University, Busan 609-735, Korea
2. School of Medicine, Jeju National University, Jeju 690-756, Korea
3. Department of Life Science, Sahmyook University, Seoul 139-742, Korea
4. College of Pharmacy, Kyung Hee University, Seoul 130-701, Korea
5. Shenyang Pharmaceutical University, Shenyang 110016, People's Republic of China