Biological activity of honey
Honey has biological activity, regardless the botanical origin. This means that honey, thanks to its complexity and content of more than 200 different substances derived from bees and plants, contributes significantly to our health. However, honeys differ in their composition, and thus their level of effectiveness. The most important and most studied biological property of honey is its antibacterial activity, which is the ability of honey to prevent the growth of bacteria or the power to kill them. Molecules responsible for antibacterial activity are often the same as those contributing to other biological activities, such as antioxidant, anti-inflammatory or wound healing. Therefore, the loss or the reduction of antibacterial activity to the level of just a sugar solution reflects the loss of other biological activities as well. Thus, it can be said that the antibacterial activity of honey is a standard representing the biological properties of honey.
Antibacterial activity of honey
The antibacterial activity of honey does not depend on just one mechanism, neither on the action of just one chemical. Antibacterial activity is based on multiple factors and their overall action. Due to the action of various independent antibacterial mechanisms and the effects of chemically different substances, honey becomes an attractive natural product without the possibility of bacteria becoming resistant. The basic and common antibacterial mechanisms common for all honeys:
- High sugar content (more than 80% saturated sugar solution), which contributes to the creation of an osmotic environment that is not suitable for bacteria to live
- Low pH (acidic pH), which also creates an environment unsuitable for bacterial growth
- Low water activity, which results in an environment where bacteria will become dehydrated
During the processing and conversion of nectar / honeydew into honey, bees secrete substances, specifically proteins and enzymes, which are a natural part of each honey, but their concentration may vary. This fact is also used to prove the authenticity of honey and each honey should contain the following antibacterial substances secreted by the bee:
- Defensin-1 (antibacterial peptide)
- Glucose oxidase (enzyme, involved in the generation of hydrogen peroxide and gluconic acid)
Some types of honey show a higher antibacterial potential compared to the others. This may be partly due to the higher content of bee antibacterial peptides, but mostly to the presence of specific substances of plant origin. Scientifically proven substances of plant origin that have a direct or indirect antibacterial effect include:
- Methylglyoxal (MGO, antibacterial chemical in manuka honey)
- Polyphenols / flavonoids (a group of secondary metabolites involved in the formation of hydrogen peroxide in diluted honeydew honeys)
Despite modern scientific approaches and new separation techniques, the exact mechanisms involved in the antibacterial effect of honey remains still unknown. It is its complexity and the synergism of substance interactions in honey that gives honey a clear competitive advantage in eliminating a different spectrum of microorganisms, even those bound in biofilms.