1. Department of Organic and Nuclear Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague 2, Czech Republic, Institute of Organic Chemistry and Biochemistry Academy of Sciences of the Czech Republic, Flemingovo n. 2, 166 10, Prague 6, Czech Republic, and Laboratory of Experimental Medicine, Department of Pediatrics, Faculty of Medicine, Palacky University and Faculty Hospital in Olomouc, Puskinova 6, 775 20 Olomouc, Czech Republic