Study finds antibiotic ciprofloxacin may be used as a new herbicide

West Australian scientists are exploring the possibilities for an antibiotic to be used as a new herbicide.

Ciprofloxacin is effective at killing bacterial infections in humans, and has recently been discovered to kill plants.

Senior lecturer at the University of Western Australia in the School of Chemistry and Biochemistry, Dr Josh Mylne, said what was most significant about the research was how ciprofloxacin killed plants.
"It kills plants in a very similar fashion to the way it kills microbes, by binding and interfering with an enzyme called gyrase, which helps the DNA unwind as it's being replicated.

"This is only something you can find in plants and bacteria," he said.

According to Dr Mylne, the way in which ciprofloxacin worked was different to existing herbicides.

"The machinery that ciprofloxacin affects is not currently targeted by known herbicides, making this an untried mode of action to focus on," Dr Mylne said.

A new mode of action has not been discovered in the last 15 to 20 years, therefore this discovery could help to overcome concerns about resistance that have affected the chemical glyphosate.

"The emerging resistance to glyphosate is obviously scaring a lot of farmers and the agro-chemical industry.

"I think everybody is jumping up and down, trying to do something about it," Dr Mylne said.

Antibiotics used to make herbicides in the past

Antibiotics are often used in plant research. In the early-1960s the well-known herbicide glyphosate was derived from an antibiotic.

"Glyphosate was an antibiotic, I don't think it was an especially good one and then some lucky sole discovered that it was a fantastic herbicide as well," Dr Mylne said.

"It was re-patented for herbicidal activity and it was used as a herbicide from there after," he said.