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The use of the bacterial efflux pump mechanism to reduce the concentrations of antibiotics in the intracellular to the extracellular region is one of the main mechanisms by which bacteria acquire resistance to antibiotics. The present study aims to evaluate the antibacterial activity of the α,β-amyrin mixture isolated from Protium heptaphyllum against the multidrug-resistant strains of Escherichia coli 06 and Staphylococcus aureus 10, and to verify the inhibition of the efflux resistance mechanisms against the strains of S. aureus 1199B and K2068, carrying the NorA and MepA efflux pumps, respectively. The α,β-amyrin did not show clinically relevant direct bacterial activity. However, the α,β-amyrin when associated with the gentamicin antibiotic presented synergistic effect against the multidrug-resistant bacterial strain of S. aureus 10. In strains with efflux pumps, α,β-amyrin was able to inhibit the action of the efflux protein NorA against Ethidium Bromide. However, this inhibitory effect was not observed in the MepA efflux pump. In addition, when evaluating the effect of standard efflux pump inhibitors, clorptomazine and CCCP, α,β-amyrin showed a decrease in MIC, demonstrating the presence of the efflux mechanism through synergism. Docking studies indicate that α, β-amyrin have a higher affinity energy to MepA, and NorA than ciprofloxacin and norfloxacin. Also, α, β-amyrin bind to the same region of the binding site as these antibiotics. It was concluded that the α, β-amyrin has the potential to increase antibacterial activity with the association of antibiotics, together with the ability to be a strong candidate for an efflux pump inhibitor. Communicated by Ramaswamy H. Sarma

Undue exposure to antimicrobials has led to the acquisition and development of sophisticated bacterial resistance mechanisms, such as efflux pumps, which are able to expel or reduce the intracellular concentration of various antibiotics, making them ineffective. Therefore, inhibiting this mechanism is a promising way to minimize the phenomenon of resistance in bacteria. In this sense, the present study sought to evaluate the activity of the Carvacrol (CAR) and Thymol (THY) terpenes as possible Efflux Pump Inhibitors (EPIs), by determining the Minimum Inhibitory Concentration (MIC) and the association of these compounds in subinhibitory concentrations with the antibiotic Norfloxacin and with Ethidium Bromide (EtBr) against strains SA-1199 (wild-type) and SA-1199B (overexpresses NorA) of Staphylococcus aureus. In order to verify the interaction of the terpenes with the NorA efflux protein, an in silico molecular modeling study was carried out. The assays used to obtain the MIC of CAR and THY were performed by broth microdilution, while the Efflux Pump inhibitory test was performed by the MIC modification method of the antibiotic Norfloxacin and EtBr. docking was performed using the Molegro Virtual Docker (MVD) program. The results of the study revealed that CAR and THY have moderate bacterial activity and are capable of reducing the MIC of Norfloxacin antibiotic and EtBr in strains of S. aureus carrying the NorA efflux pump. The docking results showed that these terpenes act as possible competitive NorA inhibitors and can be investigated as adjuvants in combined therapies aimed at reducing antibiotic resistance.

The objective of this work was to evaluate the inhibitory effect of quercetin on S. aureus Efflux Pumps. The MIC of Quercetin was evaluated through the broth microdilution method, as well as the Efflux Pump inhibition assay through the method of reducing the antibiotic minimum inhibitory concentration as well as that of ethidium bromide. The in silico approach through bioinformatics was performed to demonstrate the molecular mechanism of interaction of the substrate and the binding cavity. The Quercetin inhibition concentration was not clinically relevant. With respect to the reversal of bacterial resistance effect by efflux pump inhibition, this effect was observed with the strains carrying the TetK and NorA pumps. Regarding the interaction between the Quercetin complex and the NorA pump, the extra stability was provided by hydrogen bonds produced by the hydroxyl group.

Background Terpinolene, a monoterpene that is naturally found in a variety of herbs, is widely used as a flavoring agent in the industry. Although it's well established in the literature that terpinolene is an important component of plant extracts, the biological properties and the potential therapeutic use of this compound remain poorly explored. Purpose This work aimed to answer the following guiding question: "What are the biological activities of terpinolene demonstrated through in silico, in vitro, and in vivo assays?". Study design and methodology A systematic review was carried out in four electronic databases (Embase, Web of Science, Scopus, and PubMed) according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, using the following search terms: terpinolene “AND” activity “OR” properties “OR” therapeutic “OR” treatment. This search included manuscripts published between 1960 and June 2020. Study selection was conducted by two independent reviewers according to predefined criteria. Results The initial search found a total of 2449 articles. However, only 57 of them were selected as they met the inclusion criteria and answered the guiding question. The analysis of these studies indicated that terpinolene presents a series of biological effects, from which the antioxidant, larvicide, and insecticide activities stand out. Despite the evidence demonstrating that terpinolene has the potential to be used in a broad pharmacological context, the mechanisms underlying its cellular and molecular effects remain to be better elucidated. In addition, the in vivo efficacy and safety of the administration of this compound have been poorly evaluated through either preclinical and clinical trials. Therefore, this study highlights the importance of characterizing the biological aspects and mechanisms of action of this natural compound. Conclusion The data summarized in the present systematic review demonstrates the pharmacological potential of terpinolene. Nevertheless, most studies included in this review provide a superficial characterization of terpinolene biological effects and therefore, further research elucidating its mechanism of action and potential therapeutic benefits through preclinical and clinical trials are required. Nevertheless, due to its wide range of different biological activities, terpinolene will certainly attract the interest of scientific research, which could significantly contribute to the development of new products with both therapeutic and environmental applications.

Efflux pumps and β-lactamases are mechanisms of bacterial resistance that exist in Staphylococcus aureus, where both mechanisms are expressed simultaneously in the SA K4100 strain, with its efflux pump being characterized as QacC (Quaternary Ammonium Compounds C). The search for inhibitors of these mechanisms has grown gradually, with research on isolated compounds, including terpenes, which have innumerable biological activities, being common. This study sought to evaluate the antibacterial activity of Terpinolene against the S. aureus K4100 strain, carrying a QacC efflux pump and β-lactamase, as well as to evaluate its toxicity in the Drosophila melanogaster arthropod model. Determination of the Minimum Inhibitory Concentration (MIC) was performed by broth microdilution. Efflux pump inhibition was evaluated by the MIC reduction of Oxacillin and Ethidium Bromide (EtBr). β-Lactamase inhibition was analyzed by the MIC reduction of Ampicillin with Sulbactam. Toxicity was verified by mortality parameters and locomotor assays in D. melanogaster. The results demonstrated that Terpinolene did not present a direct antibacterial activity (MIC ≥ 1024 μg/mL). However, a reduction in MIC was observed when Terpinolene was associated with Oxacillin (161.26–71.83 μg/mL) and EtBr (45.25–32 μg/mL), possibly by a β-lactamase and efflux pump inhibition, thus evidencing a modulatory activity. Terpinolene presented D. melanogaster mortality with an EC50 of 34.6 μL/L within 12 h of exposure. Additionally, Terpinolene presented damage to the locomotor system after the second hour of exposure, with the effect increasing in a concentration-dependent manner. In conclusion, new tests should be carried out to investigate the Terpinolene reinforcement of antibiotic activity and toxic activity mechanisms of action.

A liberacao prolongada de medicamentos e caracterizada pela liberacao do principio ativo aos poucos na corrente sanguinea no sitio de acao especifico, proporciona um periodo maior no organismo do que o convencional, possuindo diversidade de formas farmaceuticas, a vantagem e na adesao ao tratamento, doses diarias reduzidas, com menos efeitos colaterais. A presente revisao teve como objetivo apresentar por meio da literatura, como a liberacao prolongada de farmacos e aplicada, discutindo tambem a sua importância. Trata-se de um estudo de revisao sistematica da literatura, no qual a busca por artigos foi feita nas seguintes bases de dados PubMed ( Publisher Medlin e), LILACS ( Literatura Latino-Americana e do Caribe em Ciencias da Saude ) e SciELO ( Scientific Eletronic Library Online ), utilizando-se os descritores liberacao prolongada de farmacos, liberacao prolongada, prolonged drug release, prolonged release. A selecao respeitou criterios de inclusao/exclusao. Foram encontrados 96 artigos dentre os selecionados apenas 15 atenderam aos criterios, abordando sistemas como niossomas, comprimidos formadores de gel in situ, microesferas, entre outros. A fabricacao desses medicamentos vem crescendo cada vez mais nos paises, pois eles apresentam de maneira significativa um tratamento mais adequado facilitando maior adesao ao tratamento com doses minimas para diversas patologias. A liberacao prolongada de medicamentos e caracterizada pela liberacao do principio ativo aos poucos na corrente sanguinea no sitio de acao especifico, proporciona um periodo maior no organismo do que o convencional, possuindo diversidade de formas farmaceuticas, a vantagem e na adesao ao tratamento, doses diarias reduzidas, com menos efeitos colaterais. A presente revisao teve como objetivo apresentar por meio da literatura, como a liberacao prolongada de farmacos e aplicada, discutindo tambem a sua importância. Trata-se de um estudo de revisao sistematica da literatura, no qual a busca por artigos foi feita nas seguintes bases de dados PubMed ( Publisher Medline ), LILACS ( Literatura Latino-Americana e do Caribe em Ciencias da Saude ) e SciELO ( Scientific Eletronic Library Online ), utilizando-se os descritores liberacao prolongada de farmacos, liberacao prolongada, prolonged drug release , prolonged release . A selecao respeitou criterios de inclusao/exclusao. Foram encontrados 96 artigos dentre os selecionados apenas 15 atenderam aos criterios, abordando sistemas como niossomas, comprimidos formadores de gel in situ , microesferas, entre outros. A fabricacao desses medicamentos vem crescendo cada vez mais nos paises, pois eles apresentam de maneira significativa um tratamento mais adequado facilitando maior adesao ao tratamento com doses minimas para diversas patologias.