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Artemisia annua

Artemisia annua, also known as Sweet Wormwood, Sweet Annie, Sweet Sagewort or Annual Wormwood is a common type of wormwood that grows throughout the world.

Characteristics

It has fern-like leaves, bright yellow flowers, and a camphor-like scent. Its height averages about 2 m tall, and the plant has a single stem, alternating branches, and alternating leaves which range 2.5-5cm in length. It is cross-pollinated by wind or insects. It is a diploid plant with chromosome number, 2n=18.

Medicinal uses

Sweet Wormwood was used by Chinese herbalists in ancient times to treat fever, but had fallen out of common use, but was rediscovered in 1970 when the Chinese Handbook of Prescriptions for Emergency Treatments (340 AD) was found. This pharmacopeia contained recipes for a tea from dried leaves, prescribed for fevers (not specifically malaria).

Extractions

In 1971, scientists demonstrated that the plant extracts had antimalarial activity in primate models, and in 1972 the active ingredient, artemisinin (formerly referred to as arteannuin), was isolated and its chemical structure described. Artemisinin may be extracted using a low boiling point solvent such as diethylether and is found in the glandular trichomes of the leaves, stems, and inflorescences, and it is concentrated in the upper portions of plant within new growth.

Parasite treatment

It is commonly used in tropical nations which can afford it, preferentially as part of a combination-cocktail with other antimalarials in order to prevent the development of parasite resistance.

Malaria treatment

Artemisinin itself is a sesquiterpene lactone with an endoperoxide bridge and has been produced semi-synthetically as an antimalarial drug. The efficacy of tea made from A. annua in the treatment of malaria is contentious. According to some authors, artemesinin is not soluble in water and the concentrations in these infusions are considered insufficient to treatment malaria. Other researchers have claimed that Artemisia annua contains a cocktail of anti-malarial substances, and insist that clinical trials be conducted to demonstrate scientifically that artemisia tea is effective in treating malaria. This simpler use may be a cheaper alternative to commercial pharmaceuticals, and may enable health dispensaries in the tropics to be more self-reliant in their malaria treatment. James Duke and Mike Benge et al, Chemical and Engineering News, Letters, Vol 83, No 18, pp4-5.

Cancer treatment

The plant has also been shown to have anti-cancer properties. It is said to have the ability to be selectively toxic to some breast cancer cells [Cancer Research 65:(23).Dec 1, 2005] and some form of prostate cancer, there have been exciting preclinical results against leukemia, and other cancer cells.

Mechanism

The proposed mechanism of action of artemisinin involves cleavage of endoperoxide bridges by iron producing free radicals (hypervalent iron-oxo species, epoxides, aldehydes, and dicarbonyl compounds) which damage biological macromolecules causing oxidative stress in the cells of the parasite. Malaria is caused by the Apicomplexan, Plasmodium falciparum, which largely resides in red blood cells and itself contains iron-rich heme-groups (in the from of haemozoin).

Other uses

In modern-day central China, specifically Hubei Province the stems of this wormwood are used as food in a salad-like form. The final product, literally termed "cold-mixed wormwood" is a slightly bitter salad with strong acid overtones from the spiced rice vinegar used as a marinade. It is considered a delicacy and is typically more expensive to buy than meat.