Wildflower’s potential to help tackle antibiotic resistance

Tormentil, a yellow wildflower found in heath and boglands in the UK, Ireland and across Europe, can inhibit the growth of one of the world’s most deadly pathogens.

A team of researchers from the University of Southampton, the NatPro Centre in Trinity College Dublin and Brunel University of London examined 70 bogland plants from across Ireland for their potential antimicrobial activity.

They discovered that Tormentil inhibits the growth of the multidrug-resistant bacterium Acinetobacter baumannii, one of the World Health Organisation’s top priority pathogens.

It means Tormentil has the potential to contribute to the development of new antimicrobials.

Ronan McCarthy, Professor in Microbial Biofilms at the National Biofilms Innovation Centre, University of Southampton, led the study which is published in the journal Microbiology and forms part of the project ‘Unlocking Nature’s Pharmacy from Bogland Species’.

He said: “It was extremely exciting to discover that this particular plant was inhibiting growth of this pathogen, and especially interesting because there is a long historical use of this plant in medicine to treat infection.”

He added: “Colistin is a last resort antibiotic, it’s our last line of antibiotic defence. When a pathogen is resistant to that there are few other options. We have discovered that there is potential for Tormentil to increase the efficacy of colistin to prolong its effectiveness and make it work better.”

The pathogen Acinetobacter baumannii is responsible for 50,000 deaths annually worldwide. It is commonly found in hospitals and can cause wound infections, respiratory infections and urinary tract infections, often in immunocompromised patients. It is hard to treat as it is resistant to most antibiotics, which is where colistin comes in.

Tormentil, with its buttercup-like yellow flowers, has been used for centuries to treat infection and is referenced in Irish and other folklore. Its name is derived from the ‘torment’ of pain it was believed to cure.

“This study underscores the value of revisiting plants long rooted in traditional knowledge and folklore and shows us that nature still has much to teach us,” said Dr John J Walsh, NatPro PI Associate Academic Director and Associate Professor of Pharmacognosy at Trinity College Dublin.

Tormentil was used as far back as the 1850s, with its roots boiled in milk to treat colic in children, and its roots used to treat toothache, wounds and stomach issues.

Professor McCarthy said: “We have uncovered historically why Tormentil was used – and it wasn’t used by accident. Granted Tormentil was not as efficacious as modern medication but in the 1850s, for example, options were fairly limited.

“There is evidence it was used for oral issues such as gum disease, and for gastrointestinal issues. Its use by physicians would have faded with the advent of modern medicine and antibiotics in particular.”

The research team took their findings further, examining the plant’s different compounds for evidence of antimicrobial activity, and how they work.

They found that two compounds – agrimoniin and ellagic acid – can kill the same pathogen, and they do it by starving it of iron. They also found that the roots, the flowers and the leaves all contain enough compound to be effective.

“This study is particularly exciting because we have established not only that Tormentil works, but how it works and why it works,” said Professor McCarthy. “It was a big hurdle to overcome to establish exactly what is responsible for the antimicrobial activity.

“Then we established that the plant grabs iron out of the environment and starves the bacteria. When we fed iron back in, we reversed the activity, confirming that the iron was responsible.”

Tormentil from three boglands in Ireland, in Wicklow, Kerry and Tipperary, all produced the same activity.

Professor Helen Sheridan, founder of the NatPro Centre and co-lead of the project, said: “When we secured funding for this bogland biodiscovery project, we hoped to find some meaningful activities in the species we investigated. Ethnomedical leads such as ‘Gargling with powdered tormentil infused in water makes loose teeth take hold again, by Johann Kúnzle (1857-1945)’, inspired us to look for antibacterial effects, and thus we reached out to the McCarthy group as leaders in the field for what has been a wonderfully successful collaboration.”

Professor McCarthy added: “The promise for Tormentil is really exciting. There is a lot of exciting work to do now to translate these findings into medications that could potentially benefit patients.”