Innovation

“In the late 1980s I received a phone call from Sid Clarke who lived in the East Cape community of Te Araroa. He represented a Māori trust which was looking into the commercial use of its substantial mānuka reserves.

 I offered to do a little work at no cost just to see if we thought there were any possible benefits. It sounded like a fun project, and you can never tell where it might lead you. A few weeks later a large sack of mānuka leaf arrived and I set up a small steam distillation unit to extract the oil. I only obtained 20 or 30ml but it was enough to have a quick look.

 The mānuka oil was subjected to a MIC test. This stands for minimum inhibitory concentration and measures the lowest concentration of the material that would stop a particular microbe from growing. The sample and a culture of the particular organism in a growth medium are incubated together. If there is no growth of the organism, then the sample at that strength is inhibiting growth. The sample is diluted by halving its strength at each step until eventually it was too weak to stop the organism growing.

With some materials, a concentration of 5 or 10 per cent might be needed to prevent bacterial growth, whereas chemicals used as preservatives in foods often work at about 0.1 to 0.2 per cent. It therefore came as a huge surprise and created great interest in the lab when our tests showed staphylococcus aureus was killed by mānuka oil at less than 0.05 per cent.

 As an aside, the active ingredients in mānuka oil are known as a class of chemicals called triketones. These chemicals had been synthetically produced in a German university chemistry lab and identified as probably having strong antimicrobial activity. They claimed the chemicals had never been identified in nature but mānuka testing proved otherwise”