• Mānuka honey has been proven to be effective against respiratory pathogens but researchers do not fully understand the mechanisms
• New research led by Dr Jonathan Cox with New Zealand mānuka honey firm Comvita has shown that a variety of bioactive compounds contribute
• As antibiotic resistance rises, understanding how possible alternatives work will be important for their effective use and application.

New research at Aston University has shown that a variety of compounds is responsible for the antimicrobial action of mānuka honey, not just the sugar content and methylglyoxal (MGO) alone, as previously thought.

Mānuka honey has already been proven to be effective against numerous disease-causing bacteria. As many bacteria become increasingly resistant to antibiotics, new approaches and treatments are required. Mānuka honey has so far not been associated with the development of resistance in the same way as antibiotics and is attracting interest. Understanding what makes mānuka honey effective is important if it is to be used consistently and effectively in future healthcare applications.

The researchers, led by Dr Jonathan Cox, a senior lecturer in biosciences at Aston University and head of the Mycobacterial Research Group, worked in partnership with scientists at New Zealand mānuka honey producer Comvita Limited to test honey with different Unique Mānuka Factor (UMF) ratings. UMF ranges from 5+ to 20+, representing a measure of the amount of MGO in the honey and guarantees that it meets the New Zealand government regulatory standard. The team tested the different honeys in the laboratory on a range of bacteria that cause respiratory infections.

The antimicrobial activity of the honey increased with increasing UMF, which was unsurprising. Dr Cox and the team also tested the antimicrobial activity of artificial formulations containing equivalent concentrations of sugar and MGO, but the antimicrobial effect could not be replicated, suggesting that additional bioactive compounds, or interactions between compounds, are responsible.

It was previously thought that the antimicrobial activity came from the MGO and the sugar content, but Dr Cox and the team have now shown that this is not the case.

The team are continuing to work closely with Comvita to identify and characterise the additional compounds that are responsible for the enhanced antimicrobial activity found in higher UMF mānuka honey. They will also look to determine how the compounds interact. Understanding these active components may support the development of more effective honey-derived therapeutics and antimicrobial products.

Dr Cox said:

“Mānuka honey is often viewed through the lens of a single compound, methylglyoxal, but our findings show that the story is far more complex. High-grade mānuka honey appears to derive its antimicrobial activity from a combination of factors working together, and understanding those interactions could help unlock new approaches to tackling infection in an era of increasing antimicrobial resistance.

“It turns out, the very nature of mānuka honey, in all its complexity, may hold a powerful solution to the emerging global AMR crisis. We just need to learn how best to use it."

Dr Jackie Evans, Comvita Limited chief science officer, said:

"Mānuka honey has long been recognised for its unique antimicrobial properties. This exciting new research shows that methylglyoxal (MGO) is only part of the story. Comvita is proud to be at the forefront of mānuka honey science, and while this is early-stage research, it highlights the importance of understanding the other bioactive compounds that contribute to its unique antimicrobial properties. Discoveries such as these are helping unlock the full potential of mānuka honey."

To read the full paper, 'UMF-dependent antimicrobial activity of Mānuka honey against respiratory pathogens cannot be explained by sugar and methylglyoxal alone' in Microbiology, visit www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.001746.