Potentiation of the Activity of Antibiotics against ATCC and MDR Bacterial Strains with (+)-α-Pinene and (-)-Borneol.

The increasing rates of antimicrobial resistance have demanded the development of new drugs as conventional antibiotics have become significantly less effective. Evidence has identified a variety of phytocompounds with the potential to be used in the combat of infections caused by multidrug-resistant (MDR) bacteria. Considering the verification that terpenes are promising antibacterial compounds, the present research aimed to evaluate the antibacterial and antibiotic-modulating activity of (+)-α-pinene and (-)-borneol against MDR bacterial strains. The broth microdilution method was used to determine the minimum inhibitory concentration (MIC) of the compounds and antibiotics and further evaluate the intrinsic and associated antibiotic activity. These analyses revealed that (+)-α-pinene showed significant antibacterial activity only against E. coli (MIC = 512 µg.mL-1), while no significant inhibition of S. aureus and P. aeruginosa growth was observed (MIC ≥ 1024 µg mL-1). However, when combined with antibiotics, this compound induced a significant improvement in the activity of conventional antibiotics, as observed for ciprofloxacin, amikacin, and gentamicin against Staphylococcus aureus, as well as for amikacin and gentamicin against Escherichia coli, and amikacin against Pseudomonas aeruginosa. On the other hand, (-)-borneol was found to inhibit the growth of E. coli and enhance the antibiotic activity of ciprofloxacin and gentamicin against S. aureus. The present findings indicate that (+)-α-pinene and (-)-borneol are phytocompounds with the potential to be used in the combat of antibacterial resistance.

Evaluation of the In Vitro Antiparasitic Effect of the Essential Oil of Cymbopogon winterianus and Its Chemical Composition Analysis.

Cymbopogon winterianus, known as "citronella grass", is an important aromatic and medicinal tropical herbaceous plant. The essential oil of C. winterianus (EOCw) is popularly used to play an important role in improving human health due to its potential as a bioactive component. The present study aimed to identify the components of the essential oil of C. winterianus and verify its leishmanicidal and trypanocidal potential, as well as the cytotoxicity in mammalian cells, in vitro. The EOCw had geraniol (42.13%), citronellal (17.31%), and citronellol (16.91%) as major constituents. The essential oil only exhibited significant cytotoxicity in mammalian fibroblasts at concentrations greater than 250 µg/mL, while regarding antipromastigote and antiepimastigote activities, they presented values considered clinically relevant, since both had LC50 < 62.5 µg/mL. It can be concluded that this is a pioneer study on the potential of the essential oil of C. winterianus and its use against the parasites T. cruzi and L. brasiliensis, and its importance is also based on this fact. Additionally, according to the results, C. winterianus was effective in presenting values of clinical relevance and low toxicity and, therefore, an indicator of popular use.

Microbial resistance: The role of efflux pump superfamilies and their respective substrates.

The microorganism resistance to antibiotics has become one of the most worrying issues for science due to the difficulties related to clinical treatment and the rapid spread of diseases. Efflux pumps are classified into six groups of carrier proteins that are part of the different types of mechanisms that contribute to resistance in microorganisms, allowing their survival. The present study aimed to carry out a bibliographic review on the superfamilies of carriers in order to understand their compositions, expressions, substrates, and role in intrinsic resistance. At first, a search for manuscripts was carried out in the databases Medline, Pubmed, ScienceDirect, and Scielo, using as descriptors: efflux pump, expression, pump inhibitors and efflux superfamily. For article selection, two criteria were taken into account: for inclusion, those published between 2000 and 2020, including textbooks, and for exclusion, duplicates and academic collections. In this research, 139,615 published articles were obtained, with 312 selected articles and 7 book chapters that best met the aim. From the comprehensive analysis, it was possible to consider that the chromosomes and genetic elements can contain genes encoding efflux pumps and are responsible for multidrug resistance. Even though this is a well-explored topic in the scientific community, understanding the behavior of antibiotics as substrates that increase the expression of pump-encoding genes has challenged medicine. This review study succinctly summarizes the most relevant features of these systems, as well as their contribution to multidrug resistance.