Evaluation of the antibacterial and inhibitory activity of NorA and MepA efflux pumps from Staphylococcus aureus by diosgenin.

The increase in bacterial resistance to available antibiotics has driven several researchers to search for new agents with therapeutic properties. Diosgenin is a naturally occurring steroidal saponin that has demonstrated several pharmacological properties. In the present study, we report the antimicrobial activity of diosgenin against the standard and multidrug-resistant bacteria of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, in addition to the efflux pump inhibitory activity against Staphylococcus aureus strains carrying NorA and MepA pumps. For this purpose, the broth microdilution method was used, from which the value of the Minimum Inhibitory Concentration (MIC) was obtained, and this was associated with subinhibitory concentration (MIC/8) with antibiotic of clinical use and ethidium bromide for strains carrier by efflux pump. Diosgenin showed antimicrobial activity for standard S. aureus bacteria and potentiating activity in association with gentamicin and ampicillin for P. aeruginosa multidrug-resistant bacteria, it also showed potentiation in association with norfloxacin against the E. coli strain and gentamicin against the S. aureus strain. Antimicrobial activity against efflux pump-bearing strains revealed that saponin did not interfere with the efflux pump mechanism or intervened antagonistically. Thus, saponin has shown to be very promising against bacterial resistance in association with aminoglycoside, fluoroquinolones and beta-lactam, however additional studies should be carried out to better elucidate the mechanism of action of diosgenin.

Comparative Analysis of the Antibacterial Activity and HPLC Phytochemical Screening of the Brazilian Red Propolis and the Resin of Dalbergia ecastaphyllum.

The aim of this study was to investigate the antibacterial activity of red propolis and resin and their association with standard antibiotics to evaluate possible differences of activity. We also submitted red propolis and the resin to a HPLC analysis to confirm the botanical origin. The extracts were tested against P. aeruginosa and S. aureus alone and in association with gentamicin and imipenem. The HPLC analysis identified seven compounds with six of them present in both substances. The lowest MIC values obtained in this study were observed against S. aureus. In general, MIC values showed to be lower for red propolis against all species tested in comparison to resin. Despite the synergistic behavior to be similar for both substances, we observed that inhibitory concentrations of drugs were lower when associated with red propolis in comparison to resin.

Antibiotic Activity Potentiation and Physicochemical Characterization of the Fixed Orbignya speciosa Almond Oil against MDR Staphylococcus aureus and Other Bacteria.

Orbignya speciosa (babassu) is an important palm tree in Brazil whose fixed almond oil is used in popular medicine and especially in food, in addition to being a research target for the manufacture of biofuels. The aim of this study was to evaluate the fixed almond oil physicochemical characterization and its antibacterial activity in isolation and in association with aminoglycosides against standard and multidrug-resistant bacteria. Analyses such as water content, pH, acidity, peroxide index, relative density, and refractive index indicate the stability and chemical quality of the oil. In the oil's GC/MS chemical composition analysis, a high saturated fatty acid (76.90%) content was observed. Lauric acid (56.28%) and oleic acid (23.10%) were the major oil components. In the antibacterial test, a more significant oil activity was observed against K. pneumoniae KP-ATCC 10031 (minimal inhibitory concentration (MIC) = 406.37 µg/mL) and Staphylococcus aureus ATCC 6538 (MIC = 812.75 µg/mL), but for the other strains-including standard and multi-resistant strains-the oil presented an MIC ≥ 1024 µg/mL. Furthermore, a synergistic effect was observed when the oil was associated with amikacin and gentamicin against S. aureus (SA-10) and an antagonistic effect was observed with amikacin against Escherichia coli. Data indicate the O. speciosa oil as a valuable nutritional source of lauric, oleic, and myristic fatty acids with an ability to modulate aminoglycoside activity.

Modulation of the Antibiotic Activity by the Mauritia flexuosa (Buriti) Fixed Oil against Methicillin-Resistant Staphylococcus Aureus (MRSA) and Other Multidrug-Resistant (MDR) Bacterial Strains.

Mauritia flexuosa (buriti) is a typical Brazilian palm tree found in swampy regions with many plant forms. The fruit has various purposes with the pulps to the seeds being used for ice creams, sweets, creams, jellies, liqueurs, and vitamin production. A physicochemical characterization of the fixed pulp oil and its antibacterial and aminoglycoside antibiotic modifying activity against Gram-positive and Gram-negative multiresistant bacterial strains were performed using broth microdilution assays. Physical properties, such as moisture, pH, acidity, peroxide index, relative density, and refractive index, indicated oil stability and chemical quality. In the GC/MS chemical composition analysis, a high content of unsaturated fatty acids (89.81%) in relation to saturated fatty acids (10.19%) was observed. Oleic acid (89.81%) was the main fatty acid identified. In the antibacterial test, the fixed oil obtained the Minimum Inhibitory Concentration (MIC) ≥ 1024 µg/mL for all standard and multiresistant bacterial strains. The synergic effect of fixed pulp oil combined was observed only in Staphylococcus aureus SA⁻10, with an MIC reduction of the gentamicin and amikacin by 40.00% and 60.55%, respectively. The data indicates the M. flexuosa fixed oil as a valuable source of oleic acid and modulator of aminoglycoside activity.