title: Synthesis and Structural Investigation of New Bio-Relevant Complexes of Lanthanides with 5-Hydroxyflavone: DNA Binding and Protein Interaction Studies.
abstract: In the present work, we attempted to develop new metal coordination complexes of the natural flavonoid 5-hydroxyflavone with Sm(III), Eu(III), Gd(III), Tb(III). The resultant hydroxo complexes have been characterized by a variety of spectroscopic techniques, including fluorescence, FT-IR, UV-Vis, EPR and mass spectral studies. The general chemical formula of the complexes is [Ln(C15H₉O₃)₃(OH)₂(H₂O)x]·nH₂O, where Ln is the lanthanide cation and x = 0 for Sm(III), x = 1 for Eu(III), Gd(III), Tb(III) andn= 0 for Sm(III), Gd(III), Tb(III),n= 1 for Eu(III), respectively. The proposed structures of the complexes were optimized by DFT calculations. Theoretical calculations and experimental determinations sustain the proposed structures of the hydroxo complexes, with two molecules of 5-hydroxyflavone acting as monoanionic bidentate chelate ligands. The interaction of the complexes with calf thymus DNA has been explored by fluorescence titration and UV-Vis absorption binding studies, and revealed that the synthesized complexes interact with DNA with binding constants (Kb) ~ 10⁴. Human serum albumin (HSA) and transferrin (Tf) binding studies have also been performed by fluorescence titration techniques (fluorescence quenching studies, synchronous fluorescence spectra). The apparent association constants (Ka) and thermodynamic parameters have been calculated from the fluorescence quenching experiment at 299 K, 308 K, and 318 K. The quenching curves indicate that the complexes bind to HSA with smaller affinity than the ligand, but to Tf with higher binding affinities than the ligand.
authors.affiliation: Department of General and Inorganic Chemistry, Faculty of Pharmacy, "Carol Davila" University of Medicine and Pharmacy, 6 Traian Vuia Str., 020956 Bucharest, Romania. alexandra.ticea@umf.ro.
authors.forename: Alexandra-Cristina
authors.initials: AC
authors.lastname: Munteanu
authors.affiliation: Department of Inorganic Chemistry, Faculty of Chemistry, University of Bucharest, 90-92 Panduri Str., 050663 Bucharest, Romania. e_m_badea@yahoo.com.
authors.forename: Mihaela
authors.initials: M
authors.lastname: Badea
authors.affiliation: Department of Inorganic Chemistry, Faculty of Chemistry, University of Bucharest, 90-92 Panduri Str., 050663 Bucharest, Romania. rodica_m_olar@yahoo.com.
authors.forename: Rodica
authors.initials: R
authors.lastname: Olar
authors.affiliation: PharmaServ. International SRL, 52 Sabinelor Str., 050853 Bucharest, Romania. dreispharmasl@aol.com.
authors.forename: Luigi
authors.initials: L
authors.lastname: Silvestro
authors.affiliation: PharmaServ. International SRL, 52 Sabinelor Str., 050853 Bucharest, Romania. dulea_c@yahoo.com.
authors.forename: Constanţa
authors.initials: C
authors.lastname: Dulea
authors.affiliation: Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH), IRASM Radiation Processing Department, Reactorului Str. 30, 077125 Magurele-Ilfov, Romania. dnegut@nipne.ro.
authors.forename: Constantin-Daniel
authors.initials: CD
authors.lastname: Negut
authors.affiliation: Department of General and Inorganic Chemistry, Faculty of Pharmacy, "Carol Davila" University of Medicine and Pharmacy, 6 Traian Vuia Str., 020956 Bucharest, Romania. uivarosi.valentina@umf.ro.
authors.forename: Valentina
authors.initials: V
authors.lastname: Uivarosi
mesh_terms: D001667:Binding, Competitive; D056831:Coordination Complexes / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D005419:Flavonoids / Q000737:chemistry*; D005453:Fluorescence; D006801:Humans; D028581:Lanthanoid Series Elements / Q000138:chemical synthesis / Q000737:chemistry*; D008024:Ligands; D008670:Metals / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D025941:Protein Interaction Mapping; D017550:Spectroscopy, Fourier Transform Infrared; D013329:Structure-Activity Relationship
chemical_list: D056831:Coordination Complexes; D005419:Flavonoids; D028581:Lanthanoid Series Elements; D008024:Ligands; D008670:Metals; C062711:5-hydroxyflavone; D004247:DNA; C427203:calf thymus DNA
keywords: HSA; calf thymus DNA; chelates; density functional calculations; lanthanides; transferrin