1. Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary, Department of Organic Chemistry, Lajos Kossuth University, P.O. Box 20, H-4010 Debrecen, Hungary, Department of Pharmacology, Semmelweis University of Medicine, P.O. Box 370, H-1445 Budapest, Hungary, Eenheid Organische Chemie, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium, and Department of Inorganic and Analytical Chemistry, Attila József University, P.O. Box...