Study of the interactions of di- and tri-terpenes from Stillingia loranthacea with the enzyme NSP16-NSP10 of SARS-CoV-2 / Estudo das interações de di- e tri-terpenos de Stillingia loranthacea com a enzima NSP16-NSP10 de SARS-CoV-2

Objective: This study aimed to evaluate the interactions of di- and tri-terpenes from Stillingia loranthacea with the enzyme NSP16-NSP10 of SARS-CoV-2, important for viral replication. Methods: The molecular docking technique was used to evaluate this interaction. Results: The analysis showed that the evaluated compounds obtained RMSD values of 0.888 to 1.944 Å and free energy of -6.1 to -9.4 kcal/mol, with the observation of hydrogen bonds, salt bridges, and pi-sulfur, pi-alkyl, and hydrophobic interactions. Conclusion: Thus, the results obtained show the potential of the compounds analyzed against the selected target. Since computer simulations are only an initial step in projects for the development of antiviral drugs, this study provides important data for future research.

Objetivo: avaliar as interações de di- e tri-terpenos de Stillingia loranthacea com a enzima NSP16-NSP10 de SARS-CoV-2, importante para a replicação viral. Métodos: A técnica de docking molecular foi utilizada para avaliar essa interação. Resultados: A análise mostrou que os compostos avaliados obtiveram valores de RMSD de 0,888 a 1,944 Å e energia livre de -6,1 a -9,4 kcal/mol, observando-se ligações de hidrogênio, pontes salinas e pi-enxofre, pi-alquil, e interações hidrofóbicas. Conclusão: Assim, os resultados obtidos mostram o potencial dos compostos analisados frente ao alvo selecionado. Como as simulações computacionais são apenas um passo inicial nos projetos de desenvolvimento de medicamentos antivirais, este estudo fornece dados importantes para pesquisas futuras.

Virtual screening based on molecular docking of lysosomotropic compounds as therapeutic agents for COVID-19 / Triagem virtual baseada no encaixe molecular de compostos lisossomotrópicos como agentes terapêuticos para COVID-19

Objective: Analyze lysosomotropic agents and their action on COVID-19 targets using the molecular docking technique. Methods: Molecular docking analyses of these lysosomotropic agents were performed, namely of fluoxetine, imipramine, chloroquine, verapamil, tamoxifen, amitriptyline, and chlorpromazine against important targets for the pathogenesis of SARS-CoV-2. Results: The results revealed that the inhibitors bind to distinct regions of Mpro COVID-19, with variations in RMSD values from 1.325 to 1.962 Å and binding free energy of -5.2 to -4.3 kcal/mol. Furthermore, the analysis of the second target showed that all inhibitors bonded at the same site as the enzyme, and the interaction resulted in an RMSD variation of 0.735 to 1.562 Å and binding free energy ranging from -6.0 to -8.7 kcal/mol. Conclusion: Therefore, this study allows proposing the use of these lysosomotropic compounds. However, these computer simulations are just an initial step toward conceiving new projects for the development of antiviral molecules.

Objetivo: aAnalisar agentes lisossomotrópicos e sua ação em alvos de COVID-19 usando a técnica de docking molecular. Métodos: Foram realizadas análises de docagem molecular destes agentes lisossomotrópicos, nomeadamente de fluoxetina, imipramina, cloroquina, verapamil, tamoxifeno, amitriptilina e clorpromazina contra alvos importantes para a patogenia do SARS-CoV-2. Resultados: Os resultados revelaram que os inibidores se ligam a regiões distintas do Mpro COVID-19, com variações nos valores de RMSD de 1.325 a 1.962 Å e energia livre de ligação de -5,2 a -4,3 kcal/mol. Além disso, a análise do segundo alvo mostrou que todos os inibidores se ligaram no mesmo sítio da enzima, e a interação resultante em uma variação de RMSD de 0,735 a 1.562 Å e energia livre de ligação variando de -6,0 a -8,7 kcal/mol. Conclusão: Portanto, este estudo permite propor o uso desses compostos lisossomotrópicos. No entanto, essas simulações em computador são apenas um passo inicial para a concepção de novos projetos para o desenvolvimento de moléculas antivirais.

Effects of ketamine in methicillin-resistant Staphylococcus aureus and in silico interaction with sortase A.

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the main human pathogens and is responsible for many diseases, ranging from skin infections to more invasive infections. These infections are dangerous and expensive to treat because these strains are resistant to a large number of conventional antibiotics. Thus, the antibacterial effect of ketamine against MRSA strains, its mechanism of action, and in silico interaction with sortase A were evaluated. The antibacterial effect of ketamine was assessed using the broth microdilution method. Subsequently, the mechanism of action was assessed using flow cytometry and molecular docking assays with sortase A. Our results showed that ketamine has a significant antibacterial activity against MRSA strains in the range of 2.49-3.73 mM. Their mechanism of action involves alterations in membrane integrity and DNA damage, reducing cell viability, and inducing apoptosis. In addition, ketamine had an affinity for S. aureus sortase A. These results indicate that this compound can be used as an alternative to develop new strategies to combat infections caused by MRSA.

Diazepam's antifungal activity in fluconazole-resistant Candida spp. and biofilm inhibition in C. albicans: evaluation of the relationship with the proteins ALS3 and SAP5.

The genus Candida spp. has been highlighted as one of the main etiological agents causing fungal infections, with Candida albicans being the most prominent, responsible for most cases of candidemia. Due to its capacity for invasion and tissue adhesion, it is associated with the formation of biofilms, mainly in the environment and hospital devices, decreasing the effectiveness of available treatments. The repositioning of drugs, which is characterized by the use of drugs already on the market for other purposes, together with molecular-docking methods can be used aiming at the faster development of new antifungals to combat micro-organisms. This study aimed to evaluate the antifungal effect of diazepam on mature C. albicans biofilms in vitro and its action on biofilm in formation, as well as its mechanism of action and interaction with structures related to the adhesion of C. albicans, ALS3 and SAP5. To determine the MIC, the broth microdilution test was used according to protocol M27-A3 (CLSI, 2008). In vitro biofilm formation tests were performed using 96-well plates, followed by molecular-docking protocols to analyse the binding agent interaction with ALS3 and SAP5 targets. The results indicate that diazepam has antimicrobial activity against planktonic cells of Candida spp. and C. albicans biofilms, interacting with important virulence factors related to biofilm formation (ALS3 and SAP5). In addition, treatment with diazepam triggered a series of events in C. albicans cells, such as loss of membrane integrity, mitochondrial depolarization and increased production of EROs, causing DNA damage and consequent cell apoptosis.