A synthetic molecule based on one found in frog egg cells could potentially be used to treat brain tumours.
The molecule is based on one from the egg cells of a frog
Amphinase is a version of a molecule isolated from the egg cells of the northern leopard frog.
UK and US scientists found it recognises the sugary coating found on a tumour cell, and latches on to it before invading and killing it.
The Journal of Molecular Biology paper suggests the molecule could potentially treat many cancers.
However, the researchers, from the University of Bath and the Alfacell Corporation, believe it shows the greatest potential in treating brain tumours, for which complex surgery and chemotherapy are the only current treatments.
Researcher Professor Ravi Acharya said: "This is a very exciting molecule.
"It is rather like Mother Nature's very own magic bullet for recognising and destroying cancer cells.
"It is highly specific at hunting and destroying tumour cells, is easily synthesised in the laboratory and offers great hope as a therapeutic treatment of the future."
Amphinase is a version of a ribonuclease enzyme, which is found in all organisms and plays a role in mopping up genetic material called RNA.
In mammals the enzyme is kept in close check, so that it does not cause damage.
But because Amphinase comes from an amphibian, and not a mammal, it is able to evade the usual defences of cancer cells, and attack them.
It will have no effect on other cells because it is only capable of recognising and binding to the sugar coating of tumour cells.
However, it is still in the early stages of development, and a treatment is not likely for several years.
Amphinase is the second anti-tumour ribonuclease to be isolated by Alfacell Corporation from northern leopard frog (Rana pipiens) egg cells.
The other, ranpirnase, is in late-stage clinical trials as a treatment for unresectable malignant mesothelioma, a rare and fatal form of lung cancer.
It is also being assessed as a treatment for non-small cell lung cancer and other solid tumours.
Dr Emma Knight, science information manager at Cancer Research UK, said: "Cancer is such a complicated disease that researchers need to explore all potential avenues.
"A similar drug to Amphinase is currently being tested against cancer in human clinical trials.
"But it's far too early to comment on whether Amphinase could ever be helpful for people with cancer."