Comprehensive Evaluation of Capparis Spinosa-Derived γ-Sitosterol Against Methicillin-Resistant Staphylococcus aureus...

Area of Science:

• Microbiology
• Natural Products Chemistry
• Pharmacology

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen due to antibiotic resistance and biofilm formation.
• Novel therapeutic strategies are needed to combat MRSA infections.
• Capparis spinosa is a plant source with potential medicinal properties.

Purpose of the Study:

• To evaluate the antibacterial, antibiofilm, and antivirulence effects of γ-Sitosterol from Capparis spinosa against MRSA.
• To confirm the presence and concentration of γ-Sitosterol in C. spinosa extracts.
• To investigate the antioxidant potential of γ-Sitosterol.

Main Methods:

• Gas chromatography-mass spectrometry (GC-MS) and Fourier Transform Infrared Spectroscopy (FT-IR) for compound identification.
• Antimicrobial assays (MIC, MBC, time-kill kinetics) to determine antibacterial activity.
• Biofilm inhibition assays, virulence factor assessment, Scanning Electron Microscopy (SEM), fluorescence imaging, quantitative Polymerase Chain Reaction (qPCR), and molecular docking for antibiofilm and antivirulence studies.
• DPPH, FRAP, and H2O2 scavenging assays for antioxidant activity evaluation.

Main Results:

• γ-Sitosterol demonstrated significant antibacterial activity with MIC of 150 µg/mL and MBC of 320 µg/mL, eradicating MRSA within 12 hours.
• It effectively inhibited MRSA biofilm formation (86%), exopolysaccharide synthesis (73%), and key virulence factors (hemolysin, catalase).
• Gene expression analysis revealed downregulation of virulence-related genes (Saes, glyB, aur), and molecular docking indicated high affinity to virulence proteins. Strong antioxidant activity was also observed.

Conclusions:

• γ-Sitosterol exhibits promising multifaceted activity against MRSA, including antibacterial, antibiofilm, and antivirulence effects.
• Its antioxidant properties further enhance its therapeutic potential.
• Further in vivo studies and molecular dynamics simulations are warranted to explore its clinical applicability against multidrug-resistant pathogens.