1. College of Pharmacy, Pusan National University, Busan 609-735, Korea, College of Pharmacy, Kyung Hee University, Seoul 130-701, Korea, Korea Research Institute of Chemical Technology, Daejon 305-343, Korea, Hannam University, Daejon 306-791, Korea, Basic Science Research Institute, Pukyong National University, Busan 608-737, Korea, and Faculdade de Farmácia, Universidade de Lisboa, Av. D. Forças Armadas, Lisboa 1600-083, Portugal