Strong antimicrobial activity and unique physicochemical characteristics in honey from Australian stingless bees , , and .

Natural products have evolved antimicrobial properties that can be exploited in our search for new ways of treating infectious diseases. This study evaluates the antimicrobial properties and chemical profiles of honey produced by the Australian stingless bee species , , and against selected human pathogens. Using broth microdilution methods, we found that all tested honey samples had antimicrobial activity. The fungal dermatophyte species displayed the highest susceptibility (average MICs: 4%-9% [wt/wt]), followed by (9%-11%), (10%-13%), and (24%-34%). honey had the highest overall activity, while honey was the weakest. After heat treatment at 80°C for 30 min to remove hydrogen peroxide (HO)-based activity, and honey retained significant non-peroxide activity against (14% and 17%, respectively) and (17% and 18%, respectively), although their efficacy against the fungal pathogens diminished. Chemical analysis revealed distinct differences in HO production, color intensity, phenolic and antioxidant content, density, and pH among the honey types. The dynamic generation of HO in stingless bee honey was remarkably prolonged, with some samples producing HO for more than 6 days. Proteomic analysis identified diverse proteins that may contribute to antimicrobial efficacy. Phenolic extracts had antimicrobial activity, with flavonoids identified as potential contributors. honey re-tested after 18 years of storage retained substantial non-peroxide-based activity. Overall, this study highlights the unique properties of stingless bee honeys and their potential as natural antimicrobial agents.IMPORTANCEAntimicrobial resistance poses a critical global health challenge. Various natural products have evolved as a defense against microbial attack and can be exploited as novel therapeutic agents. While honey from the European honey bee () is well studied, the medicinal potential of Australian stingless bee honey remains underexplored. This study demonstrates that honeys produced by the stingless bee species , , and possess unique antimicrobial properties that persist after heat treatment and following long-term storage and are distinct from the antimicrobial properties of honey bee honey. Diverse bioactive compounds, including phenolics and proteins, were seen, underscoring the complexity of these honeys as antimicrobial agents. These honeys have potential as sustainable, natural solutions for combating drug-resistant infections and could extend the scope of honey-based therapeutics.