Two thousand years ago, people could not go to the nearest pharmacy for Cold-Eeze, but they appear to have concocted their very own zinc remedy, according to a new analysis of ancient remnants.

Scientists have characterized the mineralogical and chemical ingredients of medicine from a 2,200-year-old shipwreck, revealing new insights into the pharmaceutical practices of the ancient world. Their work was published today in the Proceedings of the National Academies of Sciences.

A number of small, airtight tin containers thought to contain substances for therapeutic use were recovered from the remains of the shipwreck, discovered off the coast of Italy in the late 1980s. When scientists later unsealed one of the small containers, they found six well-preserved, grey tablets, each approximately the shape of a circular makeup sponge. A preliminary DNA analysis of the tablets in 2010 had revealed around a dozen herbal components, including carrots, parsley and wild onion, bound by clay. However, the total composition and medicinal characteristics remained unknown until now.

To explore potential medicinal uses, researchers employed a combination of analytical techniques, including mass spectrometry, X-ray diffraction, and spectroscopy.

They found that inorganic elements accounted for 80% of the total sample. Zinc, in the form of hydrozincite and smithsonite minerals, was by far the most abundant component, comprising three-quarters of the inorganic elements. Organic components, like wheat flour, vegetable and animal fats, beeswax, pollen grains, and other herbs accounted for the other 20%. “The research highlights the presence of zinc compounds as the active ingredients,” says Gianna Giachi, a chemist at the Superintendence for the Archaeological Heritage of Tuscany, in Florence, Italy.

Historical records from the era like Pliny the Elder’s Naturalis historia suggest that the main source of zinc compounds for medicine was a substance called cadmia, scraped off walls of furnaces after copper production.

Modern medicines employ zinc in a variety of uses, for example as a nutritional supplement and in fighting colds, though its efficacy and side effects remain under investigation. Ancient therapeutic uses for zinc compounds included treating dermatological ailments such as sores and ameliorating general eye conditions.

It’s the form of the discs, coupled with clues in Latin etymology in texts from that time period, that led the researchers to hypothesize that the tablets from the shipwreck were used for treating the eyes, perhaps as an eyewash. They plan on exploring the characteristics of the medicine to see if any knowledge can be used toward modern drug development.

But Alain Touwaide, a science historian at the Smithsonian Institution in Washington, DC, and part of the team that conducted the initial DNA analysis on the tablets, cautions that evidence for an eyewash interpretation is not necessarily borne out in historical records. “There are several types of cadmia, only two which are useful for eye medication. The other ones are useful for sores [or wounds],” he says. To determine whether these particular tablets were used as such scientists “need to take into consideration the populations and epidemiology in order to understand what medical conditions these tablets were supposed to treat.” This can only be done with cross-disciplinary teams that combine laboratory science with careful historical analysis, Touwaide adds.

Images courtesy of PNAS/Giachi et. al.