1. Viikki Drug Discovery Technology Center, FIN-00014 University of Helsinki, Finland, Division of Pharmaceutical Chemistry, Department of Pharmacy, P.O. Box 56, Viikinkaari 5E, FIN-00014 University of Helsinki, Finland, and Laboratory of Toxicokinetics and Metabolism, Department of Industrial Hygiene and Toxicology, Finnish Institute of Occupational Health, FIN-00250 Helsinki, Finland