Monday, April 11, 2011
PLoS One, 2011 Mar 28;6(3):e18229
Chronic wound infections and antibiotic resistance are driving interest in antimicrobial treatments that have generally been considered complementary, including antimicrobially active honey.
Australia has unique native flora and produces honey with a wide range of different physicochemical properties.
In this study we surveyed 477 honey samples, derived from native and exotic plants from various regions of Australia, for their antibacterial activity using an established screening protocol.
A level of activity considered potentially therapeutically useful was found in 274 (57%) of the honey samples, with exceptional activity seen in samples derived from marri (Corymbia calophylla), jarrah (Eucalyptus marginata) and jellybush (Leptospermum polygalifolium).
In most cases the antibacterial activity was attributable to hydrogen peroxide produced by the bee-derived enzyme glucose oxidase. Non-hydrogen peroxide activity was detected in 80 (16.8%) samples, and was most consistently seen in honey produced from Leptospermum spp.
Testing over time found the hydrogen peroxide-dependent activity in honey decreased, in some cases by 100%, and this activity was more stable at 4°C than at 25°C.
In contrast, the non-hydrogen peroxide activity of Leptospermum honey samples increased, and this was greatest in samples stored at 25°C. The stability of non-peroxide activity from other honeys was more variable, suggesting this activity may have a different cause.
We conclude that many Australian honeys have clinical potential, and that further studies into the composition and stability of their active constituents are warranted…
This study has provided a broad overview of the antibacterial activity of Australian honey and shown that many honeys have potential for therapeutic use as antibacterial agents. Jarrah and marri honeys have exceptional levels of hydrogen peroxide-dependent activity, and non-peroxide activity in Australian Leptospermum honeys is comparable to that found in New Zealand manuka honey.
These findings indicate that there is an opportunity for Australian apiarists to share in the lucrative medicinal honey market. However, the factors affecting antibacterial activity in honey are complex, numerous, and not solely dependent on the floral source. This prevents generic statements being made regarding the activity of honey derived from a given floral source, and indicates the need to test individual batches of honey for their level of antibacterial activity before they are designated as therapeutic products.