Abstract
Implant-associated bacterial infections remain a major challenge in biomaterials research, highlighting the need for effective and biocompatible strategies to prevent bacterial colonisation at implant surfaces. This study investigated the antibacterial potential of four phytochemicals-bergenin (B), norbergenin (NB), galloyl-lawsoniaside (GL), and uromyrtoside (U)-isolated from an Australian wet tropical endemic plant and evaluated the potential of bergenin as a biofunctional coating for titanium surfaces. The antibacterial activity of the phytochemicals against Staphylococcus aureus and Pseudomonas aeruginosa was assessed using zone of inhibition (ZOI), optical density (OD600), and colony-forming unit (CFU/mL) assays across concentrations of 150-1000 μg mL-1. All phytochemicals demonstrated concentration-dependent antibacterial activity, with S. aureus generally exhibiting greater susceptibility than P. aeruginosa. Against P. aeruginosa, the estimated IC50 values were 220, 232.4, 240, and 233.1 μg mL-1 for B, NB, GL, and U, respectively, whereas S. aureus exhibited IC50 values of 150 μg mL-1 for B, NB, and GL, and 733 μg mL-1 for U. Among the tested compounds, bergenin demonstrated the strongest antibacterial activity, producing a ZOI of ≥21 mm at 1000 μg mL-1 and up to 91% inhibition of bacterial growth based on OD600 measurements (p 90% reduction in bacterial viability against S. aureus after 24 h, confirming effective surface-mediated antibacterial activity. Collectively, these findings identify bergenin as a promising plant-derived antibacterial phytochemical and demonstrate its potential as a biofunctional surface modifier for developing infection-resistant titanium biomaterials. This multifunctional approach provides a promising platform for improving the antibacterial performance of titanium implant surfaces while supporting the development of plant-derived strategies for infection prevention.