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.

Potentiation of antibiotic activity, and efflux pumps inhibition by (2E)-1-(4-aminophenyl)-3-(4-fluorophenyl)prop-2-en-1-one.

In recent years, bacterial resistance to traditional drugs has increased, and the need to find new effective antibiotics to treat infections caused by multidrug-resistant bacteria has consequently become more important. The current study aimed to evaluate the potentiation of antibiotic activity and efflux pumps inhibition by (2E)-1-(4-aminophenyl)-3-(4-fluorophenyl)prop-2-en-1-one (PA-Fluorine) against the standard and resistant bacterial strains of Staphylococcus aureus and Escherichia coli. The association between PA-Fluorine and ampicillin reduced the minimum inhibitory concentration (MIC), showing a synergistic effect against S. aureus. For E. coli, PA-Fluorine did not show any significant results when associated with ampicillin. Ciprofloxacin and chlorpromazine showed synergy with PA-Fluorine on the two studied strains. An efflux pump mechanism was involved in the mechanism of action of chlorpromazine, norfloxacin, and ethidium bromide. PA-Fluorine synergistically modulated norfloxacin and bromide. It was thus concluded that PA-Fluorine has the potential to enhance antibacterial activity when combined with antibiotics. Molecular docking studies showed the effect of intermolecular interactions of PA-Fluorine on the NorA and MepA efflux pumps. Physicochemical and pharmacokinetic properties were also obtained by ADMET studies for this chalcone, which presents be a strong candidate as an efflux pump inhibitor.

Analgesic and anti-inflammatory activities of the isomeric mixture of alpha- and beta-amyrin from Protium heptaphyllum (Aubl.) march.

In the present work, we demonstrated that the mixture of alpha- and beta-amyrin (AMI) from Protium heptaphyllum has antinociceptive activity as was evident from the writhing and formalin tests in mice. AMI (10 and 50 mg/kg, i.p.) inhibited writhing in 73 and 94%, respectively, while preferentially inhibiting the 2nd phase of the response (37 and 51; and 60 and 73% inhibitions of the 1st and 2nd phases, respectively) to the formalin test. Naloxone, an opioid antagonist, did not reverse the antinociceptive effect. AMI (50 mg/kg, i.p.) was also active in the hot plate test, increasing the reaction time to thermal stimulus after 30 and 60 min, by 62 and 71%, respectively. A preventive antiedematogenic effect was observed in mice that had a carrageenan-induced paw edema. Paw volume was significantly and dose-dependently decreased by 39, 42 and 53%, three hours after administration of 10, 25 and 50 mg/kg doses, i.p., respectively. AMI (25 and 50 mg/kg, i.p.) was also able to reverse the edema already induced by carrageenan (curative effect). AMI (10 and 25 mg/kg, i.p.) was equally effective in the dextran- induced paw edema (preventive effect), reducing the paw volume by 50 and 60% at the 2nd hour, and by 63 and 73% at the third hour post-dose. AMI (50 mg/kg, i.p.) reverted the edema already formed after the dextran injection (curative effect). In conclusion, AMI demonstrated peripheral and central analgesic effects independent of the opioid system, and also showed a potent anti-inflammatory activity. The antiinflammatory activity was potentiated by both indomethacin and thalidomide, suggesting a potential involvement of prostaglandins and TNFalpha inhibitions.