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Artemisia annua

Press Release - 12 February 2007

Artemisinin – background information

The plant – Artemisia annua

Artemisia annua (Sweet Wormwood, Sweet Annie or Chinese wormwood) is a common type of wormwood that grows throughout the world. It has fern-like leaves, bright yellow flowers, and a camphor-like scent. It averages about 2 metres tall and has a single stem, alternating branches, and alternating leaves which range 2.5-5 cm in length.

A tea made from the leaves of the herb has been used as a treatment for malaria in Chinese medicine for around 3,000 years.

During the Vietnam War, Artemisia helped Vietcong soldiers avoid malaria, whilst many US GIs were killed by the disease.

In its unrefined state, the herb is also used as the ingredient that gives martini and vermouth their bitter tastes, and as a fragrance in some perfumes.

Artemisinin The active compound in the plant, artemisinin, was first isolated in the 1980s by Chinese scientists seeking an effective anti-malaria treatment among traditional Chinese medicines.

Access to the artemisinin, and the name of the plant from which it is extracted, were restricted for many years by the Chinese government.

Artemisinin also potentially has some use as a treatment for cancer; it has been shown to be selectively toxic to breast cancer cells, and has been shown to have some effectiveness against types of prostate cancer and leukaemia.

Artemisinin-based drugs are currently widely used as an anti-malaria treatment in China and Southeast Asia, which are also the main areas for the growing and processing of A. annua.

Artemisinin is an extremely reactive compound and its action is related to the presence in its structure of an endoperoxide bridge, which is unusual for natural products.

The anti-malaria action of the compound works because the malaria parasite is rich in iron from the red blood cells it feeds on. When the parasite comes into contact with artemisinin it sets of the reaction, which destroys the parasite.

When produced, the drug – as a natural product - has a shelf-life of only two years.


Extraction

The compound is toxic to the plant and grows in pockets on the leaf surface, which the plant uses as a natural defence mechanism.

Artemisinin is extracted from the plant using a solvent to separate the different parts of the plant. The raw compound is then evaporated, crystallised and purified to produce the final drug.

The solvent currently used is hexane, an alkane hydrocarbon that is both highly toxic and explosive, making it damaging to the environment and difficult to handle safely.

Using current methods, artemisinin takes eighteen months to produce, from planting the seed to extracting the compound. The plant takes a year to grow and thrives only in well-controlled climatic conditions.


Treatments

The World Health Organisation recommends a variety of combinations of anti-malaria treatments containing artemisinin and its derivatives; this is so as to improve effectiveness and reduce the likelihood of resistance developing. These treatments are known as ACTs (Artemisinin-based combination therapies).


The University of Bath is one of the UK's leading universities, with an international reputation for quality research and teaching. View a full list of the University's press releases: http://www.bath.ac.uk/news/

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