Varronia curassavica Jacq. is an aromatic species appertaining to the Boraginaceae family and has been mentioned for its numerous traditional uses and pharmacological properties, especially its antimicrobial and anti-inflammatory effects. The aim of the present study was to investigate the phytochemical profile and antifungal activities of the essential oils of V. curassavica, in addition to analyzing the ADMET properties of the majority components. The GC-MS analysis of V. curassavica essential oil (EOVC) comprised 97.36% of total composition, with α-pinene, β-caryophyllene, and bicyclogermacrene (44.46%, 22.87%, and 13.05%, respectively) as the main constituents among other minor/trace constituents. The antifungal activity of EOVC was evaluated against three Candida species and was observed with IC₅₀ > 200 μg/mL. Remarkably, the combination of EOVC with fluconazole significantly reduced the IC₅₀ required for the drug to inhibit C. tropicalis (0.003 μg/mL), C. albicans (0.7996 μg/mL), and C. krusei (17.73 μg/mL). In addition, ADME/Tox studies using α-pinene revealed that the compound poses no toxicity threats but requires caution due to its high permeability to the blood–brain barrier (BBB). Overall, the obtained results suggest that Varronia curassavica essential oil is a potentially good antifungal agent for combating fungal resistance.

Background: Substances with antibacterial properties have become crucial in light of the continuous increase in infections caused by multidrug-resistant bacteria. In this context, thiadiazines have emerged as heterocyclic compounds already known for their pharmacological activities. However, their potential as antibacterial agents and inhibitors of the efflux system found in resistant bacteria remains poorly understood. From this perspective, the present study highlights the synthesis of thiadiazine-derived compounds and evaluates their antibacterial activity and efflux pump inhibition against the Staphylococcus aureus 1199B strain. Methods: To this end, Minimum Inhibitory Concentration (MIC) tests were conducted, along with the analysis of antibacterial activity through the inhibition of the NorA efflux system using 96-well microdilution assays. Additionally, to assess efflux system inhibition, ethidium bromide (EtBr) fluorescence emission tests were performed, alongside in silico molecular docking studies. Results: Based on the results obtained, it was observed that compound IJ28 exhibited direct activity against the tested SA 1199B strains, with an MIC of 512 µg/mL. It also demonstrated antibacterial activity through efflux pump inhibition, resulting in increased fluorescence rates emitted by EtBr. Compound IJ28 showed a more significant reduction in the Minimum Inhibitory Concentration (MIC) of ethidium bromide, decreasing from 26.6 µg/mL to 0.5 µg/mL, compared to the other compounds. Conclusions: Therefore, it is essential to conduct further studies to investigate the mechanism of action and clarify the feasibility and effects of compound IJ28 as a potential antibacterial agent.

This study investigated the chemical composition and potential antibacterial activity of the essential oils from the propolis of Melipona quadrifasciata quadrifasciata (MQP) in samples collected from the cities of Paranaguá and Guaratuba, Paraná, Brazil, during summer and winter. The chemical composition of the oils was analyzed by GC-MS, and their minimum inhibitory concentration (MIC) was determined against standard ATCC strains and some clinical isolates (Escherichia coli 06 and Staphylococcus aureus 10). The essential oils’ MICs were determined using microdilution in 96-well plates and showed no significant antibacterial activity (MIC ≥ 1024 μg/mL) when used alone. However, the essential oils enhanced the action of norfloxacin, gentamicin, and ampicillin, especially against S. aureus 10. The chemical analysis identified 68 compounds, with β-bisabolene and β-caryophyllene as the predominant constituents. Subsequently, the antibiotic-enhancing activity against the clinical isolates was evaluated. The composition of the MQP oils varied according to seasonality and location, influenced by the microclimates of the cities. The results highlight the importance of MQP oils in enhancing antibiotic activity, particularly against Gram-positive bacteria, despite the lack of significant standalone antibacterial activity.

Substances with antibacterial properties have become crucial in light of the continuous increase in infections caused by multidrug-resistant bacteria. In this context, thiadiazines have emerged as heterocyclic compounds already known for their pharmacological activities. However, their potential as antibacterial agents and inhibitors of the efflux system found in resistant bacteria remains poorly understood. From this perspective, the present study highlights the synthesis of thiadiazine-derived compounds and evaluates their antibacterial activity and efflux pump inhibition against the Staphylococcus aureus 1199B strain. To this end, Minimum Inhibitory Concentration (MIC) tests were conducted, along with the analysis of antibacterial activity through the inhibition of the NorA efflux system using 96-well microdilution assays. Additionally, to assess efflux system inhibition, ethidium bromide (EtBr) fluorescence emission tests were performed, alongside in silico molecular docking studies. Based on the results obtained, it was observed that compound IJ28 exhibited direct activity against the tested SA 1199B strains, with an MIC of 512 µg/mL. It also demonstrated antibacterial activity through efflux pump inhibition, resulting in increased fluorescence rates emitted by EtBr. Compound IJ28 showed a more significant reduction in the Minimum Inhibitory Concentration (MIC) of ethidium bromide, decreasing from 26.6 µg/mL to 0.5 µg/mL, compared to the other compounds. Therefore, it is essential to conduct further studies to investigate the mechanism of action and clarify the feasibility and effects of compound IJ28 as a potential antibacterial agent.

O presente trabalho teve como objetivo realizar a avaliação do perfil químico e a atividade antibacteriana do extrato etanólico das folhas de Chenopodium ambrosioides L. contra as bactérias Streptococcus pneumoniae e Klebsiella pneumoniae. Suas folhas foram coletadas e submetidas a testes no município de Juazeiro do Norte- CE. O extrato etanólico foi produzido por técnicas de trituração, filtragem e por fim pelo processo de destilação, na qual foi analisado os seus compostos secundários e sua atividade moduladora. Na prospecção fitoquímica o extrato etanólico das folhas secas de Chenopodium ambrosioides L. (EECA) evidenciou a presença de princípios ativos como os flavonóides (flavonas, flavanonóis, chalconas, xantonas) e taninos. A atividade antibacteriana foi realizada em placas de microdiluição contendo o EECA, onde os resultados obtidos foram baseados na CLSI 2012, assim como a atividade moduladora que foram utilizados antibióticos da classe dos aminoglicosídeos e beta-lactâmicos junto ao EECA. A partir das análises foi elucidado que o EECA foi capaz de realizar um efeito modulador eficaz, além de apresentar ação sinérgica a alguns dos medicamentos testados nas cepas bacterianas klebsiella pneumoniae ATCC 4352 e Streptococcus pneumoniae ATCC 6303. Nesse estudo, concluiu-se que os parâmetros químicos e biológicos do extrato estudado, evidenciaram atividade antibacteriana e moduladora contra as bactérias estudadas e o perfil químico condizente com a atividade moduladora, visto a análise qualitativa da presença de compostos como flavonóides e taninos, justificando a atividade antibacteriana.