Avaliação da atividade antimicrobiana da hidralazina frente a Staphylococcus aureus e Candida spp

Abstract

It is estimated that infectious diseases are the leading cause of death worldwide, responsible for approximately 13 million deaths each year. Staphylococcus aureus and Candida spp are among the main human pathogens, related to several infections with different levels of severity. Available treatments are increasingly limited. S. aureus has several virulence factors, in addition to easily acquiring resistance mechanisms. While Candida spp. mainly affects immunocompromised patients, has a small available pharmacological treatment arsenal and is affected by the toxicity fact. The new antimicrobials development is a global urgency and drugs repurposing is the fastest, most economical and safest mechanism. This study aimed to evaluate the antimicrobial activity of hydralazine, in vitro, against clinical strains of S. aureus and Candida spp biofilms, and to evaluate, in silico, the possible action mechanism. By microdilution in broth, the hydralazine minimum inhibitory concentration was determined, which was on average 256 µg/ml against S. aureus. In the tolerance assessment, hydralazine proved to be bactericidal and the association with oxacillin and vancomycin was synergistic in 50 and 25% of the strains, respectively. In evaluating the cell viability of biofilms formed by S. aureus by reducing Methylthiazolyldiphenyltetrazolium bromide (MTT), the sessile minimum inhibitory concentration (50%) ranged from 256 to 2048 µg/ml. Analysis of cell viability by propidium iodide exclusion showed that hydralazine increased non-viable cells (58.78%). In the Comet and TUNEL assays, it was possible to detect breaks and the fragmentation presence in the S. aureus DNA strands. In silico, hydralazine demonstrated greater affinity and the possibility of forming lower energy complexes with the targets S. aureus gyrase complex with DNA (-7.6 kcal/mol), S. aureus gyrase (-7.3 kcal/mol) and S. aureus TyrRS (-7.5 kcal/mol). Biofilms of Candida albicans, C. parapsilosis and C. tropicalis were treated with hydralazine, itraconazole and a combination of these drugs. Reduction in cell viability was assessed by MTT metabolization. Hydralazine (10xMIC) significantly (p≤0.05) reduced the biofilms formed viability. The biofilm formation inhibition was more effective and the MIC of hydralazine for each strain was able to significantly (p≤0.05) reduce biofilm viability. In scanning electron microscopy images, it is possible to see Candida albicans cells damaged by hydralazine. In in silico assays, hydralazine demonstrates more favorable binding energy with targets Exo-B-(1,3)-glucanase (-7.1 kcal/mol) and CYP51 (-7.2 kcal/mol). Therefore, it is concluded that hydralazine has potential to be redirected to the treatment of infections caused by S. aureus and Candida spp., in association with current drugs or alone, acting on planktonic cells and also on biofilms.