Bald’s eye salve: a modern story

After remedies for head pain, the medical books turn to eye problems. It’s very clear that swollen and infected eyes were a serious issue in that time, because both books have a number of remedies. And here, we find a striking story from 2015: one of the remedies actually works, and works well.

The remedies have different preparation methods, and while most of them required only direct mixing or at most boiling the ingredients together, some of them demanded a period of time for the ingredients to sit. It might be three days, or seven, or at most, nine. Nine was a special number in the old religion.

The remedy that the University of Nottingham chose to test had a time requirement; it also required a particular type of vessel: bronze. Its ingredients list was simple compared to others, otherwise: Leeks and garlic, with ox’s gall (stomach bile), steeped in wine for nine days in a bronze dish. At the end of this period, it was to be strained with a cloth, which was probably linen. The resulting liquid was the medicine for a swollen eye.

Nottingham used glass lab equipment, but they included a brass plate so that chemicals could react with it. They chose a heritage local wine; in the Medieval Warm Period, it was easier to grow grapes in England than it has been since, so it seemed certain that anyone using this remedy in the past would be using local vintage. (I’m not sure how much they focused on heritage varieties of leeks and garlic, nor on a heritage breed of cow.)

To test the efficacy of the resulting liquid, the lab prepared some petri-dish cultures of collagen and staphylococcus bacteria. As good experimental procedure, some culture dishes were also treated with the separate ingredients. Garlic and wine, in particular, both have antibiotic properties. But staph is hard to kill, so not much was expected, neither did it happen. None of the separate ingredients had a measurable effect.

However, after nine days, the combination liquid was filtered (again, I’m not sure if they used linen but I hope so), and a staph culture had this liquid applied to it. After 24 hours, it was examined under a microscope. All of the lab personnel were astonished to find that most of the staph bacteria were dead. “About 1 in a 1000 survived,” they report.

2 + 2 = 5! The ingredients in combination had a power that none of them had together.

The test was done again, and again—four times. Each time, the test replicated the initial results. Then something even more surprising came out. They diluted the liquid:

The team then went on to see what happened if they diluted the eye salve – as it is hard to know just how much of the medicine bacteria would be exposed to when applied to a real infection.  They found that when the medicine is too dilute to kill Staphylococcus aureus, it interfered with bacterial cell-cell communication (quorum sensing).  This is a key finding, because bacteria have to talk to each other to switch on the genes that allow them to damage infected tissues.  Many microbiologists think that blocking this behaviour could be an alternative way of treating infection.

Clearly, in a time before any chemistry was understood, someone had learned through trial and error that this combination of materials created a chemical reaction that resulted in a new compound. I wonder if Nottingham has continued to experiment with the variables, for example taking a sample from the mixture each of the nine days, and finding out at what point its starts to change.

Here is the University of Nottingham press release, with a video in which the key participants discuss the experiment.


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