Anti-tubercular profile of new selenium-menadione conjugates against Mycobacterium tuberculosis H37Rv (ATCC 27294) strain and multidrug-resistant clinical isolates.

Tuberculosis (TB) is one of the most fatal diseases and is responsible for the infection of millions of people around the world. Most recently, scientific frontiers have been engaged to develop new drugs that can overcome drug-resistant TB. Following this direction, using a designed scaffold based on the combination of two separate pharmacophoric groups, a series of menadione-derived selenoesters was developed with good yields. All products were evaluated for their in vitro activity against Mycobacterium tuberculosis H37Rv and attractive results were observed, especially for the compounds 8a, 8c and 8f (MICs 2.1, 8.0 and 8.1 µM, respectively). In addition, 8a, 8c and 8f demonstrated potent in vitro activity against multidrug-resistant clinical isolates (CDCT-16 and CDCT-27) with promising MIC values ranging from 0.8 to 3.1 µM. Importantly, compounds 8a and 8c were found to be non-toxic against the Vero cell line. The SI value of 8a (>23.8) was found to be comparable to that of isoniazid (>22.7), which suggests the possibility of carrying out advanced studies on this derivative. Therefore, these menadione-derived selenoesters obtained as hybrid compounds represent promising new anti-tubercular agents to overcome TB multidrug resistance.

In vitro physiological and antibacterial characterization of ZnO nanoparticle composites in simulated porcine gastric and enteric fluids.

BACKGROUND: Diarrhea in piglets is one of the main causes of animal death after weaning; zinc oxide (ZnO) has been used in high doses for the control of this sickness. The aim of this study was to determine the physicochemical properties of ZnO nanoparticles synthesized and immobilized on a chitosan/alginate (CH/SA) complex and investigate the antimicrobial activity and in vitro release profile of zinc (Zn2+) from these new compounds. The ZnO nanoparticles composites were prepared and combined with CH/SA or CH/SA and sodium tripolyphosphate (TPP). The structure and morphology of the composites were analyzed by characterization methods such as X-ray diffraction, FTIR spectroscopy, thermogravimetric analysis, atomic absorption spectrophotometry and scanning electron microscopy. RESULTS: The crystallite size of ZnO nano was 17 nm and the novel ZnO composites were effective in protecting ZnO in simulated gastric fluid, where Zn2+ reached a concentration six-fold higher than the levels obtained with the unprotected commercial-zinc oxide. In addition, the novel composites suggest effective antimicrobial activity against Escherichia coli and Staphylococcus aureus. CONCLUSIONS: The results described herein suggest that the novel nano composites may work as an alternative product for pig feeding as verified by the in vitro assays, and may also contribute to lower the zinc released in the environment by fecal excretion in animals waste.