Corsican Chestnut Grove and Honeydew Maquis Honeys Show Strong Antimicrobial Capacity

Key role of hydrogen peroxide in antimicrobial activity of Spring, Honeydew maquis and Chestnut grove Corsican honeys on Pseudomonas aeruginosa DNA

Lett Appl Microbiol. 2018 Feb 25

In honeys, several molecules have been known for their antibacterial or wound healing properties. Corsican honeys just began to be tested for their antimicrobial activity with promising results on Pseudomonas aeruginosa.

So, identification of active molecules and their mode of action was determined.

Hydrogen peroxide concentrations were evaluated and, in parallel, the minimal inhibitory concentrations (MIC) values were performed with and without catalase. More, the quantity of phenolic compounds and ORAC assay were measured. Observation of antibacterial action was done using scanning electron microscopy (SEM) followed by plasmidic DNA extraction. MIC values of chestnut grove and honeydew maquis honeys vary between 7% and 8%, showing a strong antimicrobial capacity, associated with a plasmidic DNA degradation.

When catalase is added, MIC values significatively increase (25%) without damaging DNA, proving the importance of H2 O2 . This hypothesis is confirmed by SEM micrographies which didn't show any morphological damages but a depletion in bacterial population. Although, such low concentrations of H2 O2 (between 23 μmol.L-1 and 54 μmol.L-1 ) cannot explain antimicrobial activity and might be correlated to phenolic compounds concentration.

Thus, Corsican honeys seems to induce DNA damage when H2 O2 and phenolic compounds act in synergy by a putative pro-oxidant effect.