Inhibitory and resistance-modifying potential of plant-based alkaloids against methicillin-resistant Staphylococcus...

Area of Science:

• Microbiology
• Pharmacology
• Medicinal Chemistry

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) poses a global health threat due to high virulence and limited treatment options.
• Antibiotic resistance in MRSA is often mediated by efflux pumps, necessitating novel therapeutic strategies.
• Existing efflux pump inhibitors, like reserpine, have limitations due to toxicity concerns.

Purpose of the Study:

• To evaluate 13 alkaloid compounds as potential antimicrobial agents and/or efflux pump inhibitors (EPIs) against MRSA.
• To assess these compounds against MRSA isolates with varying vancomycin susceptibility and active efflux.
• To identify novel phytocompounds that can overcome MRSA resistance mechanisms.

Main Methods:

• Screening of 13 alkaloid compounds for antimicrobial activity (MIC determination) and efflux pump inhibition.
• Testing against three MRSA isolates with differing vancomycin resistance and efflux activity.
• Utilizing Ethidium Bromide reduction assay to quantify efflux pump inhibition, with reserpine as a positive control.

Main Results:

• Berberine exhibited moderate inhibitory activity against two MRSA isolates with a Minimum Inhibitory Concentration (MIC) of 125 µg/ml.
• Quinine, piperine, and harmaline demonstrated significant efflux inhibitory activity, reducing Ethidium Bromide MIC by two- to eightfold.
• Reserpine served as a positive control, confirming the assay's validity for detecting efflux pump inhibition.

Conclusions:

• Certain alkaloids, including berberine, quinine, piperine, and harmaline, show promise as anti-MRSA agents or efflux pump inhibitors.
• These findings highlight the potential of phytocompounds in combating antibiotic resistance.
• Further research is required to determine the pharmacodynamics and safety of these compounds for therapeutic applications.