Evaluation of Corymbia terminalis kino extracts for antibacterial activity against wound-associated pathogens:...

Kino, a red resin from Corymbia terminalis, 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 C. terminalis 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 in vivo efficacy.