Antibacterial and Antibiofilm Activities of Croton pluriglandulosus Carn.-Torres & Riina. Essential Oil and Its Membrane-Disruptive Effects

Antimicrobial resistance is a major global health concern, intensified by the misuse of antibiotics and the lack of new effective treatments. Bacteria capable of forming biofilms exhibit increased resistance, making infections more difficult to treat. This study evaluated the essential oil from Croton pluriglandulosus leaves (OCp) for its antibacterial and antibiofilm properties. The essential oil, obtained by hydrodistillation and analyzed by GC-MS, contained eucalyptol (24.11%), spathulenol (16.90%), α-pinene (11.76%), and caryophyllene oxide (10.07%) as main constituents. Antibacterial activity was determined by Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC), with inhibition observed only for Staphylococcus aureus (MIC 10 mg/mL; MBC 5 mg/mL). OCp reduced biofilm biomass and CFUs in most strains, particularly in S. aureus and Escherichia coli. Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) showed membrane damage in treated cells. Overall, OCp displayed promising antibacterial and antibiofilm potential, representing the first report of such activity for this essential oil.