Author: Tulasi Bhandari
Bhandari, Tulasi, 2025 Innovative non-thermal plasma-assisted derivatives of phloroglucinol to tackle antibiotic resistance , Flinders University, College of Medicine and Public Health
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Antimicrobial resistance (AMR) poses a serious health threat in the world, driving the search for eco-friendly and potent antimicrobial agents. Phloroglucinol, a natural phenolic compound has been confirmed to display high antibacterial properties, faces limited application due to challenges in synthetic modification. Therefore, this study aimed to overcome these challenges by using non-thermal plasma (NTP) as a green approach for controlled polymerization and functionalization of phloroglucinol, and to identify the antibacterial properties of the resulting newly synthesized derivatives.
A dielectric barrier discharge (DBD) based NTP reactor was used to treat phloroglucinol solutions with argon plasma at 200 kV, 6.5 L/min, for 30 min. The resulting products were purified by solid-phase extraction (SPE) and characterized using UV-Vis, LC-MS/MS, TOF-MS, and HPLC, confirming structural changes with added oxygenated functional groups. The antibacterial properties were then measured against Methicillin-resistant Staphylococcus aureus (MRSA) using MIC assays, confocal microscopy, ROS generation, membrane potential analysis, and SEM, with vancomycin as a control. Proteomic analysis revealed molecular mechanisms of action for MRSA inhibition.
The plasma-treated derivatives presented up to six-fold enhancement of their antibacterial activity than parent phloroglucinol, with potential for inducing oxidative stress, membrane damage, and metabolic disruption, while preserving cytocompatibility with human keratinocytes. Reproducibility of emission and chromatographic profiles confirm the consistency of method.
This work provides a rapid, scalable, and sustainable plasma-assisted method to synthesize novel phloroglucinol compounds with improved antimicrobial efficacy at the bridging of green chemistry and antimicrobial discovery. Areas to be explored in future work include improving yield and solubility, broaden microbial targets, and identifying molecular mechanisms to increase therapeutic potential.
Keywords: Keywords: Antimicrobial resistance (AMR), Non-thermal plasma, Phloroglucinol, Controlled polymerization, Minimum Inhibitory Concentration (MIC) assay, LC-MS/MS, Dielectric Barrier Discharge (DBD)
Subject: Biotechnology thesis
Thesis type: Masters
Completed: 2025
School: College of Medicine and Public Health
Supervisor: Dr. Wenshao Li