1 ICNAS/CIBIT - Institute for Nuclear Sciences Applied to Health, University of Coimbra, Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal.
2 Coimbra Chemistry Center, Chemistry Department, University of Coimbra, Rua Larga, 3004-535, Coimbra, Portugal.
3 Laboratory of Pharmacology, Faculty of Pharmacy, University of Coimbra, Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal.
4 ICNAS/CIBIT - Institute for Nuclear Sciences Applied to Health, University of Coimbra, Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal. antero@pet.uc.pt.