1. Department of Chemistry, Pukyong National University, Pusan 608-737, Korea, Laboratory of Pharmacology, College of Medicine, University of Dongguk, Kyongju, 780-714, Korea, East Sea Marine Bio Resources Research Center, Kangnung 210-702, Korea, and Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland A1A 3X9, Canada