| Artemisia annua | |
|---|---|
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Artemisia |
| Species: | A. annua |
| Binomial name | |
| Artemisia annua L. |
|
Artemisia annua, also known as Sweet Wormwood, Sweet Annie, Sweet Sagewort or Annual Wormwood (Chinese: 青蒿; pinyin: qīnghāo), is a common type of wormwood that is native to temperate Asia, but naturalized throughout the world.
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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 2.5–5 cm in length. It is cross-pollinated by wind or insects. It is a diploid plant with chromosome number, 2n=18.[1][2]
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's 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).
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.[3]
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.
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.[4][5][6] 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.[7] 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.[8] In 2004, the Ethiopian Ministry of Health changed Ethiopia’s first line anti-malaria drug from Fansidar, a sulfadoxine agent which has an average 36% treatment failure rate, to Coartem, a drug therapy containing artemesinin which is 100% effective when used correctly, despite a worldwide shortage at the time of the needed derivative from A. annua.[9]
A. annua has sedative effects on mice. Possibly mediated via benzodiazepine receptors pathways.[10]
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.[11] Malaria is caused by Apicomplexans, primarily Plasmodium falciparum, which largely resides in red blood cells and itself contains iron-rich heme-groups (in the form of hemozoin).[12]
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.