Proving its metal

Proving its metal     a plant derivative might be the promising cancer cure that oncologists have been seeking. Researchers from the University of Washington, usa, claim that a derivative of Artemesia annua (wormwood) could help cure cancer. The derivative called artemisinin is used extensively as a remedy in malaria prone regions of Asia and Africa. The method through which artemisinin attacks the malaria parasite has been identified recently, thereby giving scientists clues about how the derivative can be used against cancer.

Artemisinin is able to combat malaria because of high iron levels present in the disease-causing parasite. When artemisinin comes into contact with this iron, a chemical reaction occurs in the parasite's cells, as a result of which a large number of free radicals are formed. These radicals attack the cell membranes, breaking them apart and, thereby, killing the parasite. Narendra Singh and Henry Lai from the University of Washington's bioengineering department thought that the process might also work in case of cancer cells, which are known to be rich in iron. For example, leukemia cells' iron concentration is 1,000 times more than that of normal human body cells. Such high iron levels are a must for cancer cells to replicate dna when they divide.

The researchers used breast cancer cells and normal breast cells for their in vitro experiments. They increased iron concentration of both cancer and normal cells before exposing them to diluted artemisinin. They found that cancer cells died when exposed to holotransferrin (which helps in transport of iron into cells) followed by dihydroartemisinin (a more water-soluble form of artemisinin). After eight hours of exposure, just 25 per cent of the cancer cells remained active. After 16 hours, nearly all the cells were dead. However, normal cells exposed to both the compounds, exhibited a minimal effect. "The chemical is highly selective as it is toxic to the cancer cells, but has a marginal impact on normal breast cells,' says Lai.

The drug has been tested successfully on eight dogs suffering from different kinds of cancer and now human trials are underway. In collaboration with the Vivekanand Hospital, Meerut, India, the researchers have tested this drug on a 72-year-old man suffering from cancer of the larynx. An initial oral dose of iron followed by an injection of artemisinin was given to him. This was followed by daily injections for 15 days. The same drug was then given orally for another 50 days. At the end of this period, tests revealed that the tumour size had reduced by 70 per cent. "The patient regained his voice, appetite and weight shortly after the treatment started,' says Singh. The researchers are now testing the same drug in the us on a person suffering from pancreatic cancer. The treatment has been continuing for the last 11 months and the patient has responded positively.

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