A cost-effective colourimetric assay for quantifying hydrogen peroxide in honey.

Honey is a natural product with many beneficial properties including antimicrobial action. Production of hydrogen peroxide (H2O2) in diluted honey is central to this action. Here, we describe an optimized method for measuring levels of H2O2 in honey. This method is based on established methods, with the level of dilution, the time between dilution and reading the assay, and aeration of the samples during the assay identified as critical points for ensuring reliability and reproducibility. The method is cost-effective and easy to perform using common laboratory equipment. Using this method, we quantified the hydrogen peroxide content of five different, unprocessed polyfloral honeys collected in NC, USA. Our results show that H2O2 production by these honeys varies greatly, with some samples producing negligible levels of H2O2. We assessed the effect of colour on the assay by measuring the recovery of spiked H2O2 from light and dark honey and from serially diluted dark corn syrup, and found the amount of H2O2 that could be detected was lower in dark corn syrup and darker honey samples.

The unusual antibacterial activity of medical-grade Leptospermum honey: antibacterial spectrum, resistance and transcriptome analysis.

There is an urgent need for new, effective agents in topical wound care, and selected honeys show potential in this regard. Using a medical-grade honey, eight species of problematic wound pathogens, including those with high levels of innate or acquired antibiotic resistance, were killed by 4.0-14.8% honey, which is a concentration that can be maintained in the wound environment. Resistance to honey could not be induced under conditions that rapidly induced resistance to antibiotics. Escherichia coli macroarrays were used to determine the response of bacterial cells to a sub-lethal dose of honey. The pattern of gene expression differed to that reported for other antimicrobial agents, indicating that honey acts in a unique and multifactorial way; 78 (2%) genes were upregulated and 46 (1%) genes were downregulated more than two-fold upon exposure to the medical-grade honey. Most of the upregulated genes clustered into distinct functional regulatory groups, with many involved in stress responses, and the majority of downregulated genes encoded for products involved in protein synthesis. Taken together, these data indicate that honey is an effective topical antimicrobial agent that could help reduce some of the current pressures that are promoting antibiotic resistance.