* Drug stops parasite from evolving resistance

* Also helps other malaria drugs work better

By Maggie Fox, Health and Science Editor

WASHINGTON, April 8 (Reuters) - U.S. researchers said on Wednesday they had designed a new kind of malaria drug that kills the parasite that causes the disease and keeps it from becoming resistant to the drug.

Tests in mice show the compound also helps other malaria drugs work better, the researchers reported in the journal Nature.

Now they are looking for funding to step up development, Jane Kelly and colleagues at the Veteran Affairs Medical Center and Oregon Health and Science University in Portland said.

Malaria is a mosquito-borne disease that kills 880,000 people a year, most of them in Africa and most under the age of 5. There is no vaccine against the parasite that causes the illness and it quickly evolves resistance against drugs.

Kelly and colleagues set out to design a drug that could stop the parasite.

"When the parasite invades the human body, it takes up the red blood cells," Kelly said in a telephone interview. "They take the hemoglobin from our red blood cells and they chew it up."

The iron-containing heme in these cells is toxic to the parasites but they can convert it to a nontoxic form.

Chloroquine and other drugs stop this process but the parasite can develop the ability to pump these drugs out of its stomach.

"We engineered a new scaffold with both features incorporated into one molecule," the researchers wrote in Nature. It is called by its chemical name for now, T3.5 (3-chloro-6-(2-diethylamino-ethoxy)-10-(2-diethylamino-ethyl)- acridone).

The new drug works in the same way as the older drugs by keeping heme toxic to the parasite, plus it stops them from pumping it out of their bodies, Kelly said.

"On its own it is intrinsically potent, and in combination with other antimalarials it is synergistic," Kelly said. "It helps the other antimalarials." (Editing by Xavier Briand)

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