Síntese, caracterização e atividade biológica de complexos de ouro e prata com bases de Schiff

Abstract

The metals and their compounds have been used in medicine for over 5000 years. Currently there are several drugs containing as active center, a metal ion. Particularly, the compounds containing the metal ions Ag (I), Au (I) and Au (III) have shown good results in treatment and to fight certain types of diseases. These compounds have biological activity against some viruses and bacteria, for example, against the HIV virus, plasmodium falciparum, which causes malaria, and against M.tuberculosis that causes tuberculosis. Also, the compounds of Au (I) and Au (III) have been used to treat the symptoms of rheumatoid arthritis and cancer, respectively. Schiff bases are among the compounds most widely studied and used in research of new products and drugs, due to their easy of synthesis and versatility of their steric and electronic properties. Many compounds described in the literature are related metal complexes with ligands of this type, because, besides having great affinity for complexing the metal ions Ag (I), Au (I) and Au (III), have shown a range of biological activities, including, antifungal, anti-bacterial, anti-malarial, antiproliferative, anti-inflammatory, anti-viral and anti-antipyretic properties. The objective of this project is to synthesize, characterize and study the physicochemical properties of complexes of Ag (I) and Au (I) with Schiff bases and study later, their biological activities. The ligands were synthesized from the condensation reaction of amine (2aminotiofenol, 2-aminophenol and 2-aminobenzoic acid) with 2-carboxy-thiophene aldehyde. The BTT ligand was synthesized employing the reaction technique in a microwave oven, using silica gel as a support and solvent-free. The compounds were synthesized by adding ligands to their metal ion salt. The ligands IminaOH, BTT and IminaCOOH, were characterized by elemental analysis, vibrational, electronic and nuclear magnetic resonance spectroscopies. The ligand IminaOH had its crystal structure determined and refined by analysis technique X-ray diffraction. Based on the results obtained, we propose the following molecular formulas: C11H9NOS, for IminaOH, C11H7NS2 for BTT and C12H9NO2S, for IminaCOOH. Abstract Dissertação de Mestrado Guilherme Alves Pereira The complexes were characterized by a set of analytical and spectroscopic techniques, and data collected from these, the following molecular formulas have been proposed: [Ag(C11H7NS2)2NO3] for the complex of the ligand BTT with metal ion Ag (I) in which the ratio metal / ligand is 1:2, named AgBTT, [Au (C11H7NS2) Cl] for the complex with Au (I), entitled AuBTT, with a ratio of 1:1 metal / ligand and [Ag ( C12H8NO2S) NO3] .1/2H2O for the silver complex with the ligand IminaCOOH, called AgIminaCOOH, suggests that the proportion of 1:1:1/2 metal ion Ag (I):IminaCOOH:H2O. The ligand BTT, as well as their complexes with gold and silver, were tested against bacteria such M.tuberculosis and they demonstrated some activity. That ligand had a MIC values of 230 µM, while the complexes AgBTT and AuBTT showed MIC values of 20.7 and 34.7 µM, respectively, the MIC value obtained for the silver complex is comparable to silver sulfadiazine, used as an antibacterial compound. Note also the synergy between the ligand BTT and metal ions.