Evaluation of <i>Corymbia terminalis</i> kino extracts for antibacterial activity against wound-associated pathogens: bridging ethnopharmacology and experimental validation

Kino, a red resin from <i>Corymbia terminalis</i>, has long been used in Indigenous Australian medicine for wound care, but its antimicrobial properties remain underexplored. This study assessed the antibacterial efficacy of kino extracts against 19 wound-colonizing bacterial strains using well diffusion (WDA), minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) assays. Extracts were prepared using various organic solvents and water-based methods, including hot/cold infusion, crude aqueous extraction, and sequential solvent extractions. All kino extracts demonstrated bactericidal activity against all 19 wound-associated bacterial strains, with the methanolic and crude aqueous extracts producing the largest inhibition zones (up to 8.96 ± 0.49 mm) and the lowest MIC values (as low as 2 μg/mL). MICs ranged from 2 to 64 μg/mL, while MBCs ranged from 20 to 100 mg/mL, reflecting the higher concentrations typically required for bactericidal activity. Hot-start infusions retained antimicrobial activity, suggesting thermostability of active compounds. While organic solvents improved extraction efficiency, water-based preparations - commonly used in traditional medicine - also yielded substantial antimicrobial effects. The data affirm the potential of <i>C. terminalis</i> kino as a natural antimicrobial agent and validate its ethnopharmacological use in wound management. Future studies should isolate and characterize its active constituents and evaluate <i>in vivo</i> efficacy.