Artemisia annua: an old treatment for malaria--- a new treatment for cancer
The seed catalog season has arrived. I've already circled a new plant to grow this spring. It's called Sweet Annie or Artemisia annua. This Artemisia is a member of the wormwood family and like many of the wormwoods has interesting medicinal properties.
Sweet Annie is a popular ornamental and often used in flower arrangements and floral wreaths. As a result the seeds are relatively easy to find in catalogs. The Chinese call the plant Qinghao and have long used it for a multitude of medicinal uses. The earliest records date back to 168 BC when it was suggested for hemorrhoids. For the last two millennia it has had a reputation in treating fevers.
Back in the 1960's, on the urging of Chairman Mao, the Chinese put a great deal of time and energy into investigating medicinal plants. It was a political thing for them; they wanted to do without Western Medicine. From that time to the present a chemical extract of the plant called artemisinin has been researched and used therapeutically to treat malaria. It appears to be significantly more effective at killing the malaria causing parasite than any of the pharmaceutical drugs currently available. The World Health Organization is now promoting the manufacture and use of these extracts as a new, more effective and lower cost treatment. The Artemisia extracts are not just cheap and safe, it apparently the malaria bugs don't become resistant to the drug, a major drawback of the synthetic drugs currently in use.
Two bioengineering researchers at the University of Washington have taken the use of Artemisia a step further.
Research Professor Henry Lai and assistant research Professor Narendra Singh have exploited the chemical properties of Artemisia extracts to target breast cancer cells, with surprisingly effective results. A study in the 2001 issue of the journal Life Sciences describes how the extract killed virtually all human breast cancer cells exposed to it within 16 hours.
"Not only does it appear to be effective, but it's very selective," Lai said. "It's highly toxic to the cancer cells, but has a marginal impact on normal breast cells."
The compound helps control malaria because it reacts with the high iron concentrations found in the malaria parasite. When artemisinin comes into contact with iron, a chemical reaction ensues, spawning charged atoms that chemists call "free radicals." The free radicals attack cell membranes, breaking them apart and killing the single-cell parasite.
About seven years ago, Lai began to hypothesize that the process might work with cancer, too.
"Cancer cells need a lot of iron to replicate DNA when they divide," Lai explained. "As a result, cancer cells have much higher iron concentrations than normal cells. When we began to understand how artemisinin worked, I started wondering if we could use that knowledge to target cancer cells."
Lai devised a potential method and began to look for funding, obtaining a grant from the Breast Cancer Fund in San Francisco . Meanwhile, the University of Washington (UW) patented his idea.
The thrust of the idea, according to Lai and Singh, was to pump up the cancer cells with maximum iron concentrations, then introduce artemisinin to selectively kill the cancer. To accommodate a rate of iron intake greater than normal cells, cancer cell surfaces feature greater concentrations of transferrin receptors -- cellular pathways that allow iron into a cell. Breast cancer cells are no exception. They have five to 15 times more transferrin receptors on their surface than normal breast cells.
In the current study, the researchers subjected sets of breast cancer cells and normal breast cells to doses of holotransferrin (which binds with transferrin receptors to transport iron into cells), dihydroartemisinin (a more water-soluble form of artemisinin) and a combination of both compounds. Cells exposed to just one of the compounds showed no appreciable effect. Normal breast cells, exposed to both compounds, exhibited a minimal effect. But the response by cancer cells when hit with first holotransferrin, then dihydroartemisinin, was dramatic.
After eight hours, just 25 percent of the cancer cells remained. By the time 16 hours had passed, nearly all the cells were dead.
An earlier study involving leukemia cells yielded even more impressive results. Those cells were eliminated within eight hours. A possible explanation might be the level of iron in the leukemia cells.
"They have one of the highest iron concentrations among cancer cells," Lai explained. "Leukemia cells can have more than 1,000 times the concentration of iron that normal cells have."
The next step, according to Lai, is animal testing. Limited tests have been done in that area. In an earlier study, a dog with bone cancer so severe it couldn't walk made a complete recovery in five days after receiving the treatment.
Of the 800 or more articles on PubMed's data base on Artemisia, only about thirty deal with cancer. Of those none are describing clinical trials of Artemisia in humans. At this point it is a very curious therapy with great potential. Several doctors report anecdotal benefit in treating cancer patients but a careful examination of most of these stories finds them inconclusive. There were other therapies co-administered which may account for the supposed benefits seen. This is one of those therapies which shows great promise but which at this point is unclear whether it works with cancer. Research continues to proceed and more practitioners contribute to the anecdotal data base on Artemisia. We have contacted the pharmacy which cultivates and manufactures the Artemisia extracts that Dr. Singh and his colleagues are using in their current research. For those people running out of options for treatment this is one of those things that don't seem to hurt and just might help.
Artemisia website links of interest:
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