Synthesis, spectroscopic characterization, and antibacterial activity of chalcone (2E)-1-(3'-aminophenyl)-3-(4-dimethylaminophenyl)-prop-2-en-1-one against multiresistant Staphylococcus aureus carrier of efflux pump mechanisms and ß-lactamase.

BACKGROUND: The bacterium Staphylococcus aureus has stood out for presenting a high adaptability, acquiring resistance to multiple drugs. The search for natural or synthetic compounds with antibacterial properties capable of reversing the resistance of S. aureus is the main challenge to be overcome today. Natural products such as chalcones are substances present in the secondary metabolism of plants, presenting important biological activities such as antitumor, antidiabetic, and antimicrobial activity. OBJECTIVES: In this context, the aim of this work was to synthesize the chalcone (2E)-1-(3'-aminophenyl)-3-(4-dimethylaminophenyl)-prop-2-en-1-one with nomenclature CMADMA, confirm its structure by nuclear magnetic resonance (NMR), and evaluate its antibacterial properties. METHODS: The synthesis methodology used was that of Claisen-Schmidt, and spectroscopic characterization was performed by NMR. For microbiological assays, the broth microdilution methodology was adopted in order to analyze the antibacterial potential of chalcones and to analyze their ability to act as a possible inhibitor of ß-lactamase and efflux pump resistance mechanisms, present in S. aureus strain K4100. RESULTS: The results obtained show that CMADMA does not show direct antibacterial activity, expressing a MIC of ≥1024 µg/mL, or on the enzymatic mechanism of ß-lactamase; however, when associated with ethidium bromide in efflux pump inhibition assays, CMADMA showed promising activity by reducing the MIC of the bromide from 64 to 32 µg/mL. CONCLUSION: We conclude that the chalcone synthesized in this study is a promising substance to combat bacterial resistance, possibly acting in the inhibition of the QacC efflux pump present in S. aureus strain K4100, as evidenced by the reduction in the MIC of ethidium bromide.

Antibacterial and antibiotic modifying activity, ADMET study and molecular docking of synthetic chalcone (E)-1-(2-hydroxyphenyl)-3-(2,4-dimethoxy-3-methylphenyl)prop-2-en-1-one in strains of Staphylococcus aureus carrying NorA and MepA efflux pumps.

A large number of infections are caused by multi-resistant bacteria worldwide, adding up to a figure of around 700,000 deaths per year. Because of that many strategies are being developed in order to combat the resistance of microorganisms to drugs, in recent times, 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, which include anticancer, anti-inflammatory, antioxidants, antimicrobials, anti-tuberculosis, anti-HIV, antimalarial, anti-allergic, antifungal, antibacterial, and antileishmanial. The objective of this work was evaluate the antibacterial and antibiotic modifying activity of chalcone (E)-1-(2-hydroxyphenyl)-3-(2,4-dimethoxy-3-methylphenyl)prop-2-en-1-one against the bacteria Staphylococcus aureus carrying a NorA and MepA efflux pump. The results showed that chalcone was able to synergistically modulate the action of Norfloxacin and Ethidium Bromide against the bacteria Staphylococcus aureus 1199B and K2068, respectively. The theoretical physicochemical and pharmacokinetic properties of chalcone showed that the chalcone did not present a severe risk of toxicity such as genetic mutation or cardiotoxicity, constituting a good pharmacological active ingredient.

Chemical composition, antioxidant, antimicrobial and antibiofilm activities of Vitex gardneriana schauer leaves's essential oil.

This study aimed to determinate the chemical composition and evaluate the antimicrobial and antioxidant activity of the essential oil obtained from leaves of V. gardneriana. The Vitex gardneriana leaves's were hydrodistilled to obtain the essential oil and the chemical composition determined by GC/MS analysis. The antimicrobial activities were determined by microdilution method. The activity of essential oil on biofilm was evaluated by quantification of total biomass and enumeration of biofilm-entrapped viable cells. The antioxidant activity was assessed by DPPH free radical assay, ferrous ion chelating assay, ferric-reducing antioxidant power and ß-carotene bleaching assay. Furthermore, the essential oil was tested on viability of health human, animal cells and the microcrustacean Artemia sp. The essential oil showed high content of sesquiterpenes and very low content of monoterpenes. Regarding activity on planktonic cells, the essential oil reduced the growth of the all species tested but showed MIC values only to S. aureus (0.31%). In general, the essential oil reduced significantly the biofilm biomass and the number of viable cells of bacteria and yeasts, mainly on biofilm formation. The essential oil showed a potential antioxidant activity, mainly on ß-carotene oxidation. Moreover, the essential oil reduced the cell viability of murine fibroblasts but not show viability reduction of human keratinocytes. Furthermore, the oil not show toxicity against the microcrustacean. Thus, the essential oil from V. gardneriana leaves may be considered as an important alternative against biofilms formed by bacteria and yeasts related to infections, as well as a natural antioxidant and non-toxic substance on human cells.