ustralian scientists have discovered pineapple molecules can act as powerful anti-cancer agents and said today the research could lead to a new class of cancer-fighting drugs.

Scientists at the Queensland Institute of Medical Research said their work centred on two molecules from bromelaine, an extract derived from crushed pineapple stems that is used to tenderise meat, clarify beers and tan hides.

One of the molecules, CCZ, stimulates the body's immune system to target and kill cancer cells; the other, CCS, blocks a protein called Ras, which is defective in 30 per cent of all cancers.

QIMR researcher Tracey Mynott said her team had set out to find why the enzyme-rich bromelaine crush had such strong effects on biological material.

"In searching for these components, we discovered the CCS and CCZ proteins and found they could block growth of a broad range of tumour cells, including breast, lung, colon, ovarian and melanoma," Mynott said in a statement.

While clinical trials are a long way off, Mynott said the research had huge potential.

"The way CCS and CCZ work is different to any other drug in clinical use today," she said. "Therefore, CCS and CCZ will represent a totally new way of treating disease and potentially a whole new class of anti-cancer agent."

QIMR has launched a two-year study to examine the safety of the treatment and means of securing a reliable source of CCS and CCZ. If it succeeds, it will seek a commercial partner to develop a drug that could be used in human clinical trials.