Browsing by Author "Ramilo-Gomes, Filipa"
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- Antimicrobial and antitumor activity of S-methyl dithiocarbazate Schiff base zinc(II) complexesPublication . Ramilo-Gomes, Filipa; Alemu, Yemataw; Tekamo, Israel; Cavaco, Isabel; Campos, Débora L.; Pavan, Fernando R.; Gomes, Clara S.B.; Brito, Vanessa; Santos, Adriana O.; Domingues, Fernanda; Luís, Ângelo; Marques, M. Matilde; Pessoa, João Costa; Ferreira, Susana; Silvestre, Samuel; Correia, IsabelSchiff bases (SB) obtained from S-methyl dithiocarbazate and aromatic aldehydes: salicylaldehyde (H2L1), o-vanillin (H2L2), pyridoxal (H2L3) and 2,6-diformyl-4-methylphenol (H3L4), and their corresponding Zn(II)-complexes (1-4), are synthesized. All compounds are characterized by elemental analyses, infrared, UV-Vis, nuclear magnetic resonance spectroscopy and mass spectrometry. The structures of H2L2 and [Zn2(L1)2(H2O)(DMF)] (1a) (DMF = dimethylformamide) are solved by single crystal X-ray diffraction. The SB coordinates the metal center through the Ophenolate, Nimine and Sthiolate atoms. The radical scavenging activity is tested using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, with all ligand precursors showing IC50 values ~40 μM. Cytotoxicity studies with several tumor cell lines (PC-3, MCF-7 and Caco-2) as well as a non-tumoral cell line (NHDF) are reported. Interestingly, 1 has relevant and selective antiproliferative effect against Caco-2 cells (IC50 = 9.1 μM). Their antimicrobial activity is evaluated in five bacterial strains (Klebsiella pneumoniae, Acinetobacter baumannii, Listeria monocytogenes, Pseudomonas aeruginosa and Staphylococcus aureus) and two yeast strains (Candida albicans and Candida tropicalis) with some compounds showing bacteriostatic and fungicidal activity. The minimal inhibitory concentration (MIC90) of HnL against Mycobacterium tuberculosis is also reported, with H2L2 and H3L4 showing very high activity (MIC90 < 0.6 μg/mL). The ability of the compounds to bind bovine serum albumin (BSA) and DNA is evaluated for H3L4 and [Zn2(L4)(CH3COO)] (4), both showing high binding constants to BSA (ca. 106 M-1) and ability to bind DNA. Overall, the reported compounds show relevant antitumor and antimicrobial properties, our data indicating they may be promising compounds in several fields of medicinal chemistry.
- Naphthoylhydrazones: coordination to metal ions and biological screeningPublication . Ribeiro, Nadia; Galvao, Adelino M.; Gomes, Clara S. B.; Ramos, Helena; Pinheiro, Rute; Saraiva, Lucilia; Ntungwe, Epole; Isca, Vera; Rijo, Patricia; Cavaco, Isabel; Ramilo-Gomes, Filipa; Guedes, Rita C.; Pessoa, Joao Costa; Correia, IsabelWe report the synthesis of 3-hydroxyl-2-naphthoylhydrazones containing pyrrole (HL1), furane (HL2) and thiophene (HL3) moieties and their V(IV)O-, Cu(II)- and Zn(II)-complexes. All compounds are characterized by the usual analytical techniques and coordination of the ligands to the metal ions is discussed based on spectroscopic data (FTIR, UV-vis, EPR and NMR) as well as CAMB3LYP DFT/TDDFT calculations, indicating the formation of neutral ML2 type complexes. The photophysical properties of ligands and complexes are disclosed. The binding to Bovine Serum Albumin (BSA) is evaluated in detail using several spectroscopic tools. Circular dichroism shows that the compounds, and particularly the ligand precursors, stabilize BSA, increasing its a-helical content. Fluorescence studies indicate the formation of 1 : 1 protein-compound adducts, which is corroborated by molecular docking studies that show the interaction between Trp 213 of BSA and the naphthalene rings. The general toxicity is evaluated using the Artemia salina lethality assay, with all compounds showing general toxicity towards the brine shrimp model. The cytotoxicity on human cancer cells (H1299, MCF7, and HCT116) is assessed for all compounds and the half-maximal inhibitory concentration (IC50) values are in the range from 0.57 to 27.35 mu M. Compounds containing L-1 (pyrrole derivative) are the most cytotoxic, with the vanadium and zinc complexes performing better than the copper ones, and some of them depicting IC50 values lower than 1.1 mM. However, selectivity needs improvement as the compounds show toxicity towards Artemia salina and normal fibroblasts.