Chemical composition and antimicrobial potential of Acrocomia aculeata (Jacq.) Lodd. ex Mart. and Syagrus cearensis Noblick (Arecaceae).

This study aimed to evaluate the antibiotic effects of the fixed oils of Acrocomia aculeata (FOAA) and Syagrus cearenses (FOSC) against the bacterial strains and the fungi strains of the genus Candida spp. The method of serial microdilution using different concentrations was used for measuring the individual biological activity of the fixed oils. The fixed oil of A. aculeata showed the presence of oleic acid (24.36%), while the oil of S. cearensis displayed the content of myristic acid (18.29%), compounds detected in high concentration. The combination FOAA + Norfloxacin, and FOSC + Norfloxacin showed antibacterial activity against E. coli and S. aureus strains, demonstrating possible synergism and potentiation of the antibiotic action against multidrug-resistant strains. The combination FOAA + Fluconazole displayed a significant effect against Candida albicans (IC50 = 15.54), C. krusei (IC50 = 78.58), and C. tropicalis (IC50 = 1588 µg/mL). Regarding FOSC + Fluconazole, it was also observed their combined effect against the strains of C. albicans (IC50 = 3385 µg/mL), C. krusei (IC50 = 26.67 µg/mL), and C. tropicalis (IC50 = 1164 µg/mL). The findings of this study showed a significant synergism for both fixed oils tested when combined with the antibiotic.

Photobiological effect of eugenol-derived 3-benzoylcoumarin associated with led lights against MDR microorganisms.

The problem of antibiotic resistance by bacteria threatens human health. Therefore, studies in this area seek alternatives to circumvent it. The study with coumarins and eugenol has already proven that these classes of compounds act against bacteria. In this same aspect, exposure to LED also shows a bactericidal effect. Seeking a possible enhancement of this effect, the present work studied coumarins derived from eugenol in association with LED to investigate the bactericidal effect. Four compounds were tested. For this, minimum inhibitory concentrations (MICs) and modulation with three antibiotics against Escherichia coli and Staphylococcus aureus bacteria were determined. To test the behavior of the activity against exposure to LED, the plates were exposed for 20 min to blue light, 415 nm and then incubated at 37°C for 24 h. For control, duplicates were made, and one of them did not undergo this exposure. C1 exhibited better activity against S. aureus, as synergism prevailed under the conditions tested. C3 and C4 were promising against E. coli as they showed synergism in association with the three antibiotics both with and without LED exposure. Thus, the compounds showed bactericidal activity, and LED was shown to enhance synergism.

Dihydroeugenol derivatives associated with blue LED light: A different form to face multidrug resistant (MDR) bacteria.

Eugenol has already had its pharmacological properties elucidated in previous studies, including antibacterial and antifungal properties. Based on such information, this study aimed to evaluate the antibacterial and modulatory activity of coumarin compounds prepared from dihydroeugenol and to associate them with blue LED light for the same activity. For this study, five of the substances available: compound 1 (C1), 8-methoxy-2-oxo-6-propyl-2H-chromen-3-carboxylic acid, compound (C2), 3-(hydroxy(4-nitrophenyl)methyl)-8- methoxy-6-propyl-2H-chromen-2-one, compound 7 (C3), 8-hydroxy-3-(4-nitrobenzoyl)-6-propyl-2H-chromen-2-one, compound 8 (C4), 3-(4-aminobenzoyl)-8-methoxy-6-propyl-2H-chromen-2-one and Compound 9 (C5), 8-methoxy-3-(4-nitrobenzoyl)-6-propyl-2H-chromen-2-one 2-one. To determine the MIC, the broth microdilution technique was used. The products were evaluated for their potential to modulate the activity of antibiotics. Afterward, the plates were submitted to blue LED light for 20 min. When exposed to LED, C3 exhibited a decrease in MIC for SA ATCC and C5 for EC ATCC, with an average of 645.08 µg/mL for both cases. C2 and C4 exhibited synergism in a greater number of situations. However, C3 showed promising activity against S. aureus. C1 and C2 already acted better against E. coli, with the difference that C1 acted better against these bacteria when associated with LED. In general, the compounds studied here exhibited good antibacterial activity when associated with LED.

Effect of Carvacrol and Thymol on NorA efflux pump inhibition in multidrug-resistant (MDR) Staphylococcus aureus strains.

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.

Toxicity against Drosophila melanogaster and antiedematogenic and antimicrobial activities of Alternanthera brasiliana (L.) Kuntze (Amaranthaceae).

Bioactive phytocompounds are studied by several bioactivities demonstrated, as their cytotoxic effects. The aim of this work was to evaluate the phytochemical profile, the toxic effect using the Drosophila melanogaster animal model and the anti-inflammatory and antimicrobial effect of the Alternanthera brasiliana (EEAB) ethanol extract. The phytochemical profile was performed using HPLC. The cytotoxic effect was evaluated in vivo using D. melanogaster. The anti-inflammatory effect was determined by neurogenic and antiedematogenic assays, and the antimicrobial activity was assayed using a microdilution method to determine the minimum inhibitory concentration (MIC) of the EEAB alone and in association with antibiotics. The main compound identified on the EEAB was luteolin (1.93%). Its cytotoxic effect was demonstrated after 24 h in the concentrations of 10, 20 and 40 mg/mL. The extract demonstrated an antiedematogenic effect, with a reduction of the edema between 35.57 and 64.17%. The MIC of the extract was ≥1.024 µg/mL, thus being considered clinically irrelevant. However, when the EEAB was associated with gentamicin, a synergism against all bacterial strains assayed was observed: Staphylococcus aureus (SA10), Escherichia coli (EC06) and Pseudomonas aeruginosa (PA24). Due to these results, the EEAB demonstrated a low toxicity in vivo and anti-inflammatory and synergistic activities. These are promising results, mainly against microbial pathogens, and the compounds identified can be a source of carbon backbones for the discovery and creation of new drugs.