London: Researchers have shed light on a mystifying side-effect of taking aspirin: the drug apparently lowers a person's chances of developing some forms of cancer.

Exactly why a key ingredient in the painkiller -salicylate - shows such potential as an anti-cancer treatment has remained unclear since long, but a new study in mice has offered clues.

Aspirin, which is one of the world's oldest medicines known for its anti-inflammatory and analgesic effects, rapidly breaks down inside the body into salicylate.

To investigate aspirin's unexpected side-effects, Grahame Hardie at the University of Dundee, UK applied salicylate to cultured human cells derived from the kidney.

He discovered that the drug activated AMPK, an enzyme involved in cell growth and metabolism that has been found to play a role in cancer and diabetes, New Scientist reported. "This is an ancient herbal remedy which has probably always been part of the human diet," said Hardie. "But despite that we're still finding out how it works."

Co-author Greg Steinberg of McMaster University in Hamilton, Ontario, Canada, then tested high doses of salicylate on different types of mice.

He found that those engineered to lack AMPK did not experience similar metabolic effects from salicylate as observed in mice with AMPK.

Salicylate, in a form called salsalate, has also shown potential as a treatment for insulin-resistance and type 2 diabetes.

Those effects, however, seem not to be governed by AMPK. When insulin-resistant mice lacking AMPK were given salicylate, they demonstrated the same improvement in blood glucose levels as normal mice.

"That''s what makes aspirin so scientifically and clinically interesting," said Chris Paraskeva at the University of Bristol, UK, who was not involved in the work. "It potentially works through a number of different pathways."

The study has successfully separated aspirin's pain-relieving effects from its cancer protection, paving the way for new anti-cancer drugs that have lesser side-effects than aspirin.

(Agencies)