Avaliação do potencial antimicrobiano de novos compostos híbridos contendo os farmacóforos sulfonamida e 2-aminotiofeno

Abstract

The increased morbidity and mortality caused by bacterial infection is a public health issue and has lead a debate about the worldwide emergence of multiresistant microorganisms. Part of this phenomenon is due to the indiscriminate use of antibiotics, which allowed the microorganisms to develop resistance mechanisms. Therefore, it is necessary to constantly seeking to develop new drug candidates to antimicrobial agents. One of medicinal chemistry strategies for the antibiotics development is the molecular hybridization, which allows the combination of different pharmacophores in a single molecule, increasing them therapeutic potential. In this context this study aimed to evaluate the in vitro antibacterial activity of novel synthetic hybrid compounds containing the sulfonamide and 2-amino-thiophene pharmacophores. Thus, seven new derivatives have been synthesized in two reaction steps, starting with the Gewald reaction (obtaining 2-amino- thiophenes), followed by condensation of these with 4- acetamido -benzene sulfonyl chloride using 40 kHz ultrasound irradiation. The compounds were purified, characterized and have their structures confirmed by H NMR. Finally we determine the minimum inhibitory concentrations (MIC) and its activities as modifiers of antibiotic activity (putative efflux pump inhibitors) by microdilution, in Staphylococcus aureus strains overexpressing the NorA , MrsA and TetK genes. The hybrid compounds were obtained until 80 minutes in satisfactory yields (40-99%), demonstrating that ultrasound irradiation is a viable and appropriate option. Although none of the compounds showed significant in vitro antibacterial activity (≥ 256µg/mL), some compounds such as Sulfa 01, 02 and 04 acted as modifiers activity antibiotic, presumably by inhibiting the efflux pump, in particular the strain SA - 1199B (which overexpresses the norA gene) reducing the Norfloxacin CIM up to 16 times (128 to 8 mg / mL). How sulfonamides have no inhibitory action of efflux pumps, our results lead us to believe that thiophene moiety is responsible for this activity, suggesting that the new hybridized compounds when in vivo (they refer to prodrugs) may act by two distinct mechanisms of action, potentiating their actions. The results indicate that the new hybrid derivatives are potential candidates for antibiotics prototypes, with great potential to act by a synergistic action mechanism.