Deciphering the biological activity of propolis (bee glue) and its constituents; what is its potential as an antimicrobial?

Area of expertise: I have a very strong background on the action of antimicrobials and their resistance, I originally trained on the study of disinfectant mechanisms of action and resistance with a number of publications on the topic. For some years I have investigated the antimicrobial properties of plant extracts such as tinctures and oils as well as specific phytochemicals. More recently, through a collaboration with a company in North Yorkshire I have become involved in the study of propolis, a product of the hive. Propolis is a resinous substance used by the bees for protection. It is highly complex, comprising in excess of 300 different chemicals; it is also very variable as its chemical composition depends on the time of year collected, the plants the bees are harvesting from and thus the geographical location.

In my group we are utilising our expertise to study the antimicrobial and antioxidant properties of propolis from different geographical locations in order to establish a link between the different aspects of biological activity with chemical composition. We are also investigating the effect of propolis on biofilm formation and quorum sensing, as well as its effects on antibiotic resistance.

Future goals: There is general awareness of the potential of propolis, from researchers and clinicians alike. However, understanding of this amazing product is relatively limited particularly regarding its biological activity as most of the research has been carried out by chemists analysing the different components. We would like to further understand the extent of the biological activity of propolis particularly regarding its antimicrobial and antioxidant activity. So that in the future we will be able to elucidate its mechanism (or most likely mechanisms) of action.

The main hurdles we currently face is regarding solubility which makes the use of established methodologies such as MICs very challenging. We are looking for researchers with experience in alternatives to these tests, particularly for test compounds with very limited solubility, as many phytochemicals are.

It has been suggested by colleagues that perhaps it would be necessary to investigate the effects of propolis on the whole organism at the molecular level, and thus carry out genomic and proteomic analysis following exposure to propolis. We would like to make links with researchers with experience of this kind of analysis to help us further understand the outcome of this kind of investigations. In the longer term in order to be able to work towards conducting clinical trials we would benefit from contacts with researchers that have taken work through this process.