FTIR analysis and antimicrobial activity of sodium tungstate and calcium tungstate

Abstract

In recent years, many antibacterial agents have been produced with the aim of eradicating infectious diseases, but many of these agents are ineffective against the resistance presented by bacteria. It is currently estimated that more than 60 % of current antibiotics are ineffective, so the discovery of new drugs is vital. Among the compounds studied in recent years are polyoxotungstates, inorganic compounds targeted for their pharmacological properties. The aim of this study was therefore to chemically characterize two tungstates: calcium and sodium, and to evaluate their microbiological properties, both in combination with antibiotics and due to their ability to reverse the resistance process represented by the expression of the enzyme betalactamase. The microbiological tests were carried out using the microdilution technique, with colorimetric disclosure, using resazurin, and the chemical characterization and vibrational modes of the compounds were evaluated using Fourier transform infrared spectroscopy with attenuated total reflectance. Calcium tungstate showed four spectroscopic bands, located between 84 and 1915 cm⁻¹, while sodium tungstate showed two bands at 335 and 935 cm⁻¹. Calcium tungstate intensified the effect of gentamicin against the bacterium Escherichia coli 06, as well as reversing the mechanism of enzymatic resistance presented by the bacteria Staphylococcus aureus K-4100 and K-4414. Given the current scenario of resistance, these results represent new alternatives for the treatment of bacterial infections, allowing a better understanding of the properties of polyoxometalates. These results are unprecedented as far as the literature is concerned.