ADMET study, spectroscopic characterization and effect of synthetic nitro chalcone in combination with norfloxacin, ciprofloxacin, and ethidium bromide against Staphylococcus aureus efflux pumps

Naringenin as potentiator of norfloxacin efficacy through inhibition of the NorA efflux pump in Staphylococcus aureus

Bacterial resistance is a major challenge in the treatment of Staphylococcus aureus infections, with efflux mechanisms highlighted as reducing the efficacy of antibiotics. In this study, we investigated the potential of naringenin, a natural flavonoid, as an antibacterial agent and efflux pump inhibitor in S. aureus strains 1199 and 1199B. The studies used minimum inhibitory concentration (MIC) assays, ethidium bromide (EtBr) fluorescence emission enhancement assays, cell membrane permeability assays, and in silico molecular docking and ADME prediction assays. Naringenin showed no relevant antibacterial activity (MIC ≥1024 μg/mL). However, it potentiated the effect of norfloxacin and EtBr, reducing their MICs and increasing the fluorescence emission of EtBr, suggesting a possible inhibition of the NorA efflux pump. Bacterial membrane permeability was not significantly affected. Molecular docking assays indicated that naringenin interacts with the chlorpromazine binding site and has more favorable affinity energy than the chlorpromazine-NorA complex. ADME prediction showed favorable physicochemical properties, good oral absorption, metabolic stability and central nervous system safety. Therefore, naringenin demonstrates the potential to reverse the efficacy of norfloxacin in S. aureus by associating with efflux inhibition through effective interactions with the NorA protein, suggesting its therapeutic potential against bacterial resistance.

Synthesis, molecular docking, ADMET, and evaluation of the anxiolytic effect in adult zebrafish of synthetic chalcone (E)-3-(4-(dimethylamino)phenyl)-1-(2-hydroxyphenyl)prop-2-en-1-one: An in vivo and in silico approach

BACKGROUND

Anxiety disorders represent the complex interaction between biological, psychological, temperamental, and environmental factors; drugs available to treat anxiety such as benzodiazepines (BZDs) are associated with several unwanted side effects. Although there are useful treatments, there is still a need for more effective anxiolytics with better safety profiles than BZDs. Chalcones or 1,3-diphenyl-2-proper-1-ones can be an alternative since this class of compounds has shown therapeutic potential mainly due to interactions with GABAA receptors and serotonergic system.

OBJECTIVES

This study evaluated the anxiolytic potential of chalcone (E)-3-(4-(dimethylamino)phenyl)-1-(2-hydroxyphenyl)prop-2-en-1-one (C2OHPDA) in adult zebrafish (Danio rerio) (ZFa).

METHODS

Each animal (n = 6/group) was treated intraperitoneally (i.p.; 20 μL) with the chalcone (4, 20, and 40 mg/kg) and with the vehicle (DMSO 3%; 20 μL), being submitted to the tests of locomotor activity and 96-h acute toxicity. The light/dark test was also performed, and the serotonergic mechanism (5-HT) was evaluated through the antagonists of the 5-HTR1 , 5-HTR2A/2C , and 5-HTR3A/3B receptors. It was investigated the prediction of the chalcone's position and preferential orientation concerning its receptor, as well as the pharmacokinetic parameters (ADMET) involved in the process after administration.

RESULTS

As a result, C2OHPDA was not toxic and reduced the locomotor activity of ZFa. Furthermore, chalcone demonstrated an anxiolytic effect on the central nervous system (CNS), mediated by the serotonergic system, with action on 5-HT2A and 5-HTR3A/3B receptors. The interaction of C2OHPDA with 5-HT2A R and 5-HT3A receptors was confirmed by molecular docking study, the affinity energy observed was -8.7 and -9.1 kcal/mol, respectively.

CONCLUSION

Thus, this study adds new evidence and highlights that chalcone can potentially be used to develop compounds with anxiolytic properties.

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 β-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 β-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 β-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.

Inhibition of Multidrug Efflux Pumps Belonging to the Major Facilitator Superfamily in Bacterial Pathogens

Bacterial pathogens resistant to multiple structurally distinct antimicrobial agents are causative agents of infectious disease, and they thus constitute a serious concern for public health. Of the various bacterial mechanisms for antimicrobial resistance, active efflux is a well-known system that extrudes clinically relevant antimicrobial agents, rendering specific pathogens recalcitrant to the growth-inhibitory effects of multiple drugs. In particular, multidrug efflux pump members of the major facilitator superfamily constitute central resistance systems in bacterial pathogens. This review article addresses the recent efforts to modulate these antimicrobial efflux transporters from a molecular perspective. Such investigations can potentially restore the clinical efficacy of infectious disease chemotherapy.