Insulin in a plant seed

An edible plant seed could deliver your insulin or cancer drugs if David Craik’s research progresses as hoped. His team’s work at The University of Queensland’s Institute for Molecular Bioscience centres on cyclotides, which are a family of exceptionally stable circular proteins that occur naturally in many plants, such as violets and petunia.

Circular proteins naturally occuring in plants such as petunia have inspired David Craik’s research. Credit: The University of Queensland

Inspired by the stability and diversity of natural cyclotides, David’s team has developed a way to join the two ends of a linear protein, allowing them to create ‘designer’ cyclotides that can be incorporated into crop plants, turning them into production factories for therapeutic drugs and insecticides.

“Essentially, we’re recreating the structure of natural circular molecules and replacing part of their sequence to give them a pharmaceutical or agricultural activity,” David says. “We can then incorporate the corresponding new gene, with its improved benefits, into plants which can naturally reproduce it.”

One pharmaceutical application would be to simply harvest the plant, purifying the drug to produce a tablet. Or, by producing these molecules in edible plants or seeds, they could make the drugs easily and cheaply available, particularly for people in developing countries—though the work needs to be scaled up to get higher yields.

In agriculture, designer cyclotides with an insecticidal activity could be incorporated into crops such as cotton to give them a built-in pest protection.

So far they have had success with the re-engineered cyclotides for treating pain and obesity in animal and test tube models, although the research is yet to reach clinical trials. In future, the strength and stability of cyclotides may also be exploited for drugs, such as insulin, which currently have to be injected.

David received the 2014 Ramaciotti Medal for Excellence in Biomedical Research and the 34th GlaxoSmithKline Award for Research Excellence.

For more information: The University of Queensland, Gemma Ward,,