1. Department of Pharmaceutical Chemistry, University of Kuopio, PO Box 1627, FI-70211 Kuopio, Finland, Department of Pharmacology and Toxicology, University of Kuopio, PO Box 1627, FI-70211 Kuopio, Finland, and Department of Chemistry, University of Kuopio, PO Box 1627, FI-70211 Kuopio, Finland