No abstract

No abstract

The acute respiratory syndrome caused by the SARS-CoV-2, known as COVID-19, has been ruthlessly tormenting the world population for more than six months. However, so far no effective drug or vaccine against this plague have emerged yet, despite the huge effort in course by researchers and pharmaceutical companies worldwide. Willing to contribute with this fight to defeat COVID-19, we performed a virtual screening study on a library containing Food and Drug Administration (FDA) approved drugs, in a search for molecules capable of hitting three main molecular targets of SARS-CoV-2 currently available in the Protein Data Bank (PDB). Our results were refined with further molecular dynamics (MD) simulations and MM-PBSA calculations and pointed to 7 multi-target hits which we propose here for experimental evaluation and repurposing as potential drugs against COVID-19. Additional rounds of docking, MD simulations and MM-PBSA calculations with remdesivir suggested that this compound can also work as a multi-target drug against SARS-CoV-2.

In this work we investigated the possibility of substituting diphenylamine (DPA) by the natural product guaiacol, as a stabilizer for nitrocellulose (NC)-based propellants. Stability evaluation, using heat-ux calorimetry (HFC), revealed lower heat ows associated with our guaiacol-stabilized propellant samples when compared to those of propellants stabilized with the traditional stabilizers. Also, pressure-vacuum stability tests (PVST) showed that our propellant exhibited lower evolved gas volumes. Traditional tests, such as the German Test, and the Bergmann-Junk Test, scored a NO volume, after titration, of 0.87 ml (below the limit-value for acceptance, which is 2.0 ml), and the Storage Test, showed that our samples are stable and do not degrade for more than 3 days when submitted to a constant temperature of 100°C. The homogeneity, stability and compatibility of our samples were evaluated through scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and isothermal thermogravimetry (TG).Ballistic parameters were estimated using a closed vessel along with ad hoc codes, for comparison purposes. Finally, a high-performance liquid chromatography (HPLC) method developed before allowed inferring the stabilizer consumption after arti cial ageing of samples. Such method also showed that the material met the correspondent stability criteria (AOP-48). In short, our results clearly indicate that guaiacol is an effective and e cient substitute for DPA as a propellant stabilizer for single base nitrocellulose-based propellants, making them more environmentally friendly.

No abstract