RESUMO
We aimed to synthesize a new series of triazacyclononanyl-porphyrins (4 and 5) with the potential ability to bind DNA. For this, the free-base porphyrin 4 and the corresponding Zn(ii)-complex 5 were synthesized by the Schiff base formation reaction. The binding ability of the porphyrin derivatives 4 and 5 with DNA from calf-thymus was studied by UV-vis and emission spectroscopy. Detailed analysis of the results suggests that the interaction of these systems most probably occurs through π-stacking and secondary hydrogen interaction surface binding with ct-DNA. Moreover, we also demonstrate the substantial ability of porphyrins 4 and 5 to generate (1)O2 and to photocleave plasmid DNA after irradiation.
Assuntos
Porfirinas/química , Zinco/química , Animais , Bovinos , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Espectrometria de Fluorescência , Espectrofotometria UltravioletaRESUMO
Pharmaceuticals and their metabolites constitute a class of xenobiotics commonly found in aquatic environments which may cause toxic effects in aquatic organisms. Several different lipophilic molecules, including some pharmaceuticals, can bind to fatty acid-binding proteins (FABPs), a group of evolutionarily related cytoplasmic proteins that belong to the intracellular lipid-binding protein (iLBP) family. An oyster FABP genome-wide investigation was not available until a recent study on gene organization, protein structure, and phylogeny of Crassostrea gigas iLBPs. Higher transcript levels of the C. gigas FABP2 gene were found after exposure to sewage and pharmaceuticals. Because of its relevance as a potential biomarker of aquatic contamination, in this study, recombinant FABP2 from C. gigas (CgFABP2) was successfully cloned, expressed, and purified, and in vitro and in silico assays were performed using lipids and pharmaceuticals. This is the first characterization of a protein from the iLBP family in C. gigas. Homology modeling and molecular docking were used to evaluate the binding affinities of natural ligands (palmitic, oleic, and arachidonic acids) and pharmaceuticals (ibuprofen, sodium diclofenac, and acetaminophen). Among the tested fatty acids, CgFABP2 showed preference for palmitic acid. The selected pharmaceuticals presented a biphasic-binding mode, suggesting a different binding affinity with a preference for diclofenac. Therefore, the approach using circular dichroism and in silico data might be useful for ligand-binding screening in an invertebrate model organism.
Assuntos
Crassostrea , Preparações Farmacêuticas , Animais , Crassostrea/genética , Proteínas de Ligação a Ácido Graxo/genética , Simulação de Acoplamento Molecular , FilogeniaRESUMO
The present work reports the spectroscopic and theoretical evaluation of the interaction between calf-thymus DNA (CT-DNA) and free-base meso-tetra-(ruthenated) porphyrin (H2RuTPyP) or its corresponding Zn(II) complex (ZnRuTPyP). Spectroscopic measurements (UV-vis, circular dichroism and steady-state fluorescence emission) combined with theoretical molecular docking calculations suggest that Ru(II)-porphyrins interact with the DNA backbone by external mode via electrostatic forces. In addition, gel electrophoresis analysis demonstrate that these porphyrins promote efficient plasmidial DNA photocleavage upon white-light irradiation conditions, indicating H2RuTPyP and ZnRuTPyP as potential candidates for photodynamic therapy.
Assuntos
Complexos de Coordenação/química , Clivagem do DNA/efeitos da radiação , DNA/efeitos da radiação , Fármacos Fotossensibilizantes/química , Porfirinas/química , Rutênio/química , Zinco/química , Cátions/química , Complexos de Coordenação/farmacologia , Sequestradores de Radicais Livres/química , Luz , Simulação de Acoplamento Molecular , Fotoquimioterapia , Fármacos Fotossensibilizantes/farmacologia , Espécies Reativas de Oxigênio/química , Eletricidade Estática , Relação Estrutura-AtividadeRESUMO
In this work, we evaluate the interaction of the peripheral Pt(bpy)Cl+ substituted porphyrins, H2PtPor and ZnPtPor with DNA using UV-vis, emission fluorescence, CD spectroscopy, and DNA melting properties altered by the Pt(ii)-porphyrinoid compounds. Additionally, we observe the ability of these porphyrin derivatives to generate 1O2 and to efficiently photocleave plasmid DNA upon visible light irradiation based on a mixed (oxidative/hydrolytic) mechanism.