Artemisinin could selectively kill cancer cells while normal cells unharmed

University of Washington

Researchers at the University of Washington have blended the past with the present in the fight against cancer, synthesis of a promising new compound from an ancient Chinese remedy, the cancer cells' rapacious appetite for iron, so that they target.

The substance, artemisinin, is made from the wormwood plant and has been in China since ancient times to treat malaria. Earlier work by Henry Lai and Narendra Singh, both UW Bioengineering indicated that artemisinin alone could selectively kill cancer cells while normal cells unharmed.

The new compound appears to improve significantly, that the deadly selectivity, according to a new study in a recent issue of the journal Life Sciences. In addition to Lai and Singh, Co-authors include Tomikazu Sasaki and Archna Messay, both UW chemists.

"By itself, artemisinin is about 100 times more selective in killing cancer cells, unlike normal cells," Lai said. "In this study, the new artemisinin compound was 34,000 times stronger in killing the cancer cells, in contrast to their normal cousins. Thus, the tagging seems to have greatly the effectiveness of artemisinin to cancer-killing properties increased."

The substance was developed in Chongqing Holley Holdings license and Holley Pharmaceuticals, its U.S. subsidiary, for possible use in humans. Although the compound is promising, say the officials, possible use for humans is still years away.

In the study, researchers exposed human leukemia cells and white blood cells to the substance. While the leukemia cells quickly died, the white blood cells remained essentially unharmed.

The trick to the compound of effectiveness, according to Lai seems in the use of the function, such as cancer cells.

Because they multiply so quickly that most cancer cells need more iron than normal cells, DNA replication. To facilitate that, cancer cells have inlets on their surface, known as transferrin receptors, in which more than other cells. These receptors allow quick transport into the cell of transferrin, an iron-protein found in the blood.

The preparation of the compound, researchers bound artemisinin to transferrin at the molecular level. The combination of the two components is to fool the cancer cell.

"We call it a Trojan horse because the cancer cell recognizes transferrin as a natural, harmless protein," Lai said. "So the cell, the liaison, not knowing that a bomb - artemisinin - hiding inside."

Once inside the cell, the artemisinin reacts with the iron, spawning highly reactive chemicals called "free radicals". The attack of free radicals and other molecules in the cell membrane, it breaks apart and killing the cell.

According to Lai, that process is what initially piqued his interest in artemisinin over 10 years. The wormwood extract was lost centuries ago in China, but the treatment was over time. In the 1970s it was again as part of an ancient manuscript, medical measures, including a recipe, a wormwood extract. The medical community soon discovered that the extract, artemisinin, well against malaria, and it is currently available for this purpose in all of Asia and Africa.

Artemisinin against malaria because the malaria parasite collects high iron concentrations, as hemoglobin metabolism in the blood. As science began to understand how artemisinin worked, Lai said he began to wonder if the process had implications for cancer treatment.

"I think that maybe we can use this knowledge to selectively target cancer cells," he said. "So far, the outlook seems to be good.

Artemisinin is a secondary plant substance, chemically a sesquiterpene that occurs in the leaves and flowers of annuals mugwort (Artemisia annua). Characteristics of Artemisinin structure are a Trioxanringsystem and Peroxide bridge. It is in Vietnam, China and Africa for the treatment of infections with multidrug-resistant strains of Plasmodium falciparum, the causative agent of malaria tropica used. In June 2009, however, were known from Cambodia, the first resistance.

Artemisinin production

The extraction is carried through the extraction of dried leaves and flowers with hexane, in which the active ingredient, which is predominantly localized in the essential oil glands, scales, is soluble. On an area of one hectare can be harvested up to two tonnes of leaf material, which provide two to three kilograms of the extract. The Artemisinin content in the plant is between 0.1 and 0.4% based on dry weight. Engineered with an active ingredient are known up to 1.4%. Evaporated from the crude extract, a yellow, viscous oil, artemisinin is obtained by recrystallization, however, this process is relatively expensive and thus is the price of artemisinin is very high.

Experimentally, more recently, the biosynthesis in genetically modified E. coli bacteria and Saccharomyces cerevisiae explored. Initial successes are on the way to artificial substitutes already exist. [3] Jay Keasling it is supported by the Bill and Melinda Gates Foundation with $ 43,000,000, the work of

Artemisinin effectiveness

Artemisinin has a Peroxide bridge, which is unstable in the presence of high concentrations of iron ions to form free radicals. Such high concentrations are found in red blood cells, but also in plasmodia, accumulate iron. Where artemisinin in Plasmodium infected red blood cells are formed free radicals, and the parasite may be killed by it. Meanwhile, however, summarize the evidence that artemisinin derivatives act specifically, for example by pfATP6 that inhibit a Ca-ATPase. A molecule-specific effect would be better explained as a purely chemical and physical effect of the occasional emergence of resistance. Due to the tremendous versatility of the malaria parasite seem to form also against artemisinin resistance.

Mugwort against malaria

However, as in the 70 years he was discovered during archaeological excavations of the last century, a recipe mugwort against malaria, began again to deal with the herb. The different active ingredients such as artemether, artesunate and artemisinin have been isolated. Artesunate is water soluble, very effective and has a short half-life. Artemether is oil-and water-soluble and therefore can pass the blood brain barrier. But it has a longer half-life, which means that it is also toxic. Artesiminin lies in the half-life in between and can also pass the blood brain barrier. Therefore, it is one of the few resources that are used since the Vietnam war against acute malaria and recognized by the World Health Organization WHO.

Efficacy against malaria

Artemisinin reacts with the high iron concentrations in the malaria pathogens. If artemisinin is in contact with iron, a chemical reaction occurs. It produces charged atoms, which we know as free radicals. In the treatment of malaria attack the free radicals in the cell membranes of malaria parasite and break them. So they kill the parasites.

Cancer in Germany

Each year, 436 000 people in Germany to new cancer, 211 500 people die every year of it. Experts estimate that the number of cases of cancer will increase by the year 2030 by 50 percent. The reason: People are living longer and cancer is a disease that affects especially older people.

Most common cancers in men

With about 58 570 new cases in prostate cancer in Germany is now the most common cancer in men main reason is the growing proportion of older men. The mean age of onset is 69 years. Are in second place with 37 250 new cases of colorectal cancer in men. Lung cancer in men with documented diseases 32 850 per year for third place.

Most cancers of women

Most common cancer of women is breast cancer. Every year 57 230 women are diagnosed in Germany in it. The mean age of onset is 63 years. 40 percent of affected women are younger than 60 years. Ranks second in the women with 36,000 new cases of colon cancer. Even among women with lung cancer is 13 190 now in third place. The cause of smoking: more and more women!

Childhood cancer

Every year in Germany, approximately 1,800 children and adolescents under 15 years newly diagnosed with cancer. This number is constant for many years. The chances of recovery are now at 80 percent. Malignant neoplasms in children still remains the second leading cause of death. The most common childhood cancers are leukemia (blood cancer), tumors of the brain and spinal cord and lymph node cancer.

Cancer numbers worldwide

Each year, more than 11 million people worldwide new cancer. 7.9 million die from it. This cancer is the second leading cause of death. Experts believe that cancer in 2030, 16 million people each year from cancer. The main reason: there are more older people.

The most common cancers (the sequence follows the death rate):

Women are diagnosed most frequently in breast, lung, stomach and colon cancer. In men, occur most frequently the lungs, stomach, liver, colon, esophagus and prostate cancer.

The most common cancer killers are lung, stomach, liver, colon and breast cancer. Some 72 percent of people who died in 2007 of cancer, lived in countries with low or moderate incomes.

Tobacco smoke is the biggest risk factor that leads to cancer.

Ahmad, H., Singh, SV, Awasthi, YC: Inhibition of bovine lens glutathione S-transferases by hematin, bilirubin, and bromosulfophthalein. Lens Eye Toxic Res 8, 431-440, 1991
Lai, H., Singh, N.: "Artemisinin and Cancer", Cancer Letters, 91:41-46, 1995

Lai, H., Singh, N.: "Artemisinin and Cancer", International Journal of Oncology 18:767-772, 2001 by Efferth et.al. and Life Sciences, Nov. 2002

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