UROS 2017 Project: Can Allicin be used as a cell mediator for current antibiotics

By Megan Mortimer


Garlic has been shown to have significant synergistic antimicrobial properties, specifically the compound called allicin. An allicin preparation was tested in conjunction with a panel of common antibiotics (Vancomycin, Ampicillin, and Moemycin A) against clinically relevant bacteria (E. coli strains, P. aeruginosa strains, K. pneumoniae, MRSA and MSSA). Allicin had to be synthesized on site due to the commercial unavailability. To achieve this alliinase was extracted from a cell free preparation of fresh garlic through a combination of centrifugation and dialysis. The combination of alliinase with allicin precursor alliin and co factor pyridoxal 5-phosphate monohydrate in accordance with the literature. The resultant solution was then used in the preparation of antimicrobial susceptibility tests.

However, no synergistic effect was observed between allicin and any of the selected antibiotics. There are many potential reasons for this, the short half-life of allicin, the insufficient conversion of alliin to allicin or merely the lack of combinative biological activity, storage of CFE alliinase, concentrations of various compounds used in the MICs and financial constraints.
Further work could be improved by using the optimised extraction techniques described in the literature, to increase the chances of extracting the alliinase. A mass spec analysis of the biotransformation to show the reaction products (allicin). An NMR would elucidate any interactions between allicin and the antimicrobials. Repeating the experiment with a varying amount of DDT is also a possibility as it would affect the disulphide bonds in allicin. Using different bacterial strains is also a possibility, along with testing different antimicrobials with different modes of action.

The six weeks in the lab has been an incredible learning experience. I feel so much more prepared to enter work or continue studying. I have learnt important skills such as microbiology techniques, experimental procedure, how to correctly fill out the paperwork necessary to operate safely in category 1 and 2 laboratories. I have improved my time management skills. I learnt how the labs run, and how to overcome barriers in my experiment.
These skills and the past few weeks will help me in my dissertation and future career as a scientist.


*To view Megan’s project poster, please click on the thumbnail below