Childbirth tea may stop caterpillar scourge

University of Queensland and Institute for Molecular Biology researcher Prof David Craik has isolated a protein that could help stop the advance of the voracious Helicoverpa caterpillar through our agricultural backyard.

"This is a very interesting mechanism, although we are still not completely sure how it works," Craik said.

The cyclic cystine knot protein came to Craik's attention through its ability to resist boiling when taken as 'katala katala tea', a traditional childbirth stimulant used in Africa.

Using NMR spectroscopy, Craik discovered that the shape of this protein was cyclical, or circular.

This meant there were no 'ends' for biological enzymes to attack and break down. This structural aspect of the protein, coupled with another unique aspect, cystine knots, made it very stable in biological systems.

"But we noted that [the tea] not only withstood boiling, but that it had powerful uterine action qualities, so obviously it had some other properties the plant needed," he said.

Craik and his team assumed the protein was probably an inbuilt insect defence, developed within the plant. This led to investigation on its action against a range of agricultural pests.

"We still don't know the action of the molecule, but we do know it is effective against the caterpillars," he said. "Primarily it retards growth, and about 40-50 per cent of the sample die, with the rest simply not growing to the reproductive stage -- so as such it effectively stops the rampage of the caterpillar and moth on any crop," he added.

Craik said the original discovery had spun out from ongoing research on circular proteins as a potential delivery mechanism for therapeutics. He said the unique shape of the protein, and its stability, made it highly attractive as an oral delivery vehicle able to withstand enzymes within the highly acidic digestive system.

"This was a very interesting [side] discovery, and we are looking at the protein's potential for a whole range of other uses including other agbio applications," he affirmed.

"We are still trying to find out exactly how it works; we have some theories but nothing we can say just yet," he added.