Antibacterial and antibiotic modifying activity of chalcone (2E)-1-(4'-aminophenyl)-3-(4-methoxyphenyl)-prop-2-en-1-one in strains of Staphylococcus aureus carrying NorA and MepA efflux pumps: In vitro and in silico approaches.

A large number of infections are caused by multi-resistant bacteria worldwide, increasing to around 700,000 deaths per year. Because of that, many strategies are being developed to combat the resistance of microorganisms to drugs, and recently, chalcones have been studied for this purpose. Chalcones are known as α, ß-unsaturated ketones, characterized by having the presence of two aromatic rings that are joined by a three-carbon chain. They are a class of compounds considered an exceptional model due to chemical simplicity and a wide variety of biological activities, including anticancer, anti-inflammatory, antioxidants, antimicrobials, anti-tuberculosis, anti-HIV, antimalarial, anti-allergic, antifungal, antibacterial, and antileishmaniasis. The objective of this work was to evaluate the antibacterial and antibiotic modifying activity of chalcone (2E)-1-(4'-aminophenyl)-3-(4-methoxyphenyl)-prop-2-en-1-one against the bacteria Staphylococcus aureus carrying a NorA and MepA efflux pump. The results showed that chalcone showed no toxicity on macrophage cells and was able to synergistically modulate the action of Norfloxacin and Ethidium Bromide against the bacteria Staphylococcus aureus 1199B and K2068, respectively. Furthermore, the theoretical physicochemical and pharmacokinetic properties of chalcone showed that it did not present a severe risk of toxicity such as genetic mutation or cardiotoxicity, constituting an excellent pharmacological active ingredient.

Essential Oil of Croton ceanothifolius Baill. Potentiates the Effect of Antibiotics against Multiresistant Bacteria.

This study is a pioneer in reporting the antibacterial properties of the species Croton ceanothifolius Baill. The genus Croton belongs to the family Euphorbiaceae composed of numerous species with documented biological activities. However, the pharmacological properties of C. ceanothifolius remain poorly understood. The leaves of this plant were submitted to hydrodistillation for essential oil (CcEO) extraction and the phytochemical characterization of the oil was performed by GC/MS. The minimum inhibitory concentration of the CcEO was determined for the evaluation of antibacterial activity against multiresistant strains of Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. The antibiotic-modulating activity of the oil, in combination with antibiotics, was also evaluated. The combination of the CcEO with penicillin, norfloxacin, and gentamicin presented a synergistic effect. This effect was more significant for the association with antibiotics of the quinolone and aminoglycoside classes against Escherichia coli. The association of oil with gentamicin showed better results with regard to the Gram-positive strain. The association of the oil with norfloxacin against P. aeruginosa also showed synergism, but the association with penicillin did not change the effect of this antibiotic. Thus, it is concluded that C. ceanothifolius essential oil selectively potentiates the action of antibiotics against multiresistant strains.

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.