1. Department of Chemistry, Coimbra University, P-3004-535 Portugal, Department of Chemistry, Jadavpur University, Calcutta 700 032, India, Faculté de Pharmacie, Laboratoire de Pharmacologie et Physicochimie, Université Louis Paster, BP 24, 67401 Illkirch, France, and The Palladin Institute of Biochemistry, Kiev 01030 Ukraine