A natural substance found in red wine, mulberries, peanuts and beansprouts may help prevent cancer.
The molecule - called resveratrol - helps to fight the fungus that can blight many crops.
But researchers have discovered that it is also converted in the body to a known anti-cancer agent that can selectively target and destroy cancer cells.
Studies have suggested before that resveratrol might be cancer preventing - but this is the first time that scientists have gained a deeper insight into the underlying mechanism.
The research was carried out by Professor Gerry Potter and his team from Leicester's De Montfort University.
Professor Potter said: "Learning from nature in this way will help in our work to design drugs which are selectively activated in a tumour and can form the basis of anti cancer-treatments.
"Resveratrol is a defensive molecule against fungus in grapes and other crops, and is found at higher levels in those which have not been treated with man-made fungicides."
Source BBC News