Artemisia annua

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.

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 2.5–5 cm in length. It is cross-pollinated by wind or insects. It is a diploid plant with chromosome number, 2n=18.^[1][2]

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'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).

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.^[3]

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

Qinghao (Artemisia annua) has been long used as antimalarial herb in China

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]

Other medicinal Uses

A. annua has sedative effects on mice. Possibly mediated via benzodiazepine receptors pathways.^[10]

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.^[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 from of hemozoin).^[12]

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.

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  Artemisia annua habitus

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  Artemisia annua: detail of a inflorescense

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  Seeds

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  Artemisia annua

References

1. ^ Kreitschitz, A.; J. Vallès (September 2003). "New or rare data on chromosome numbers in several taxa of the genus Artemisia (Asteraceae) in Poland". Folia Geobotanica 38 (3): 333–343. doi:10.1007/BF02803203. 
2. ^ Rotreklová, O.; P. Bure and V. Grulich (2004). "Chromosome numbers for some species of vascular plants from Europe". Biologia, Bratislava 59 (4): 425–433. http://biologia.savba.sk/59_4_04/Rotreklova_O.pdf. 
3. ^ Duke SO, Paul RN (1993). "Development and Fine Structure of the Glandular Trichomes of Artemisia annua L.". Int. J Plant Sci. 154 (1): 107–18. doi:10.1086/297096. JSTOR 2995610. 
   Ferreira JFS, Janick J (1995). "Floral Morphology of Artemisia annua with Special Reference to Trichomes". Int. J Plant Sci. 156 (6): 807. doi:10.1086/297304. http://www.journals.uchicago.edu/doi/abs/10.1086/297304. 
4. ^ Mueller MS, Runyambo, Wagner I, et al. (2004). "Randomized controlled trial of a traditional preparation of Artemisia annua L. (Annual Wormwood) in the treatment of malaria". Trans R Soc Trop Med Hyg 98 (5): 318–21. doi:10.1016/j.trstmh.2003.09.001. PMID 15109558. 
5. ^ Räth K, Taxis K, Walz GH, et al. (1 February 2004). "Pharmacokinetic study of artemisinin after oral intake of a traditional preparation of Artemisia annua L. (annual wormwood)". Am J Trop Med Hyg 70 (2): 128–32. PMID 14993622. http://www.ajtmh.org/cgi/content/full/70/2/128. 
6. ^ Jansen FH (2006). "The herbal tea approach for artemesinin as a therapy for malaria?". Trans R Soc Trop Med Hyg 100 (3): 285–6. doi:10.1016/j.trstmh.2005.08.004. PMID 16274712. 
7. ^ "Anamed Artemisia programme", Anamed International website (accessed 12 March 2009)
8. ^ Duke J, Benge M, et al. (May 2, 2005). "Letters". Chemical and Engineering News 83 (18): 4–5. http://pubs.acs.org/isubscribe/journals/cen/83/i18/html/8318lett.html. 
9. ^ "Malaria Update", Focus on Ethiopia, April 2005, UN-OCHA website (accessed 12 March 2009)
10. ^ Emadi F, Yassa N, Hadjiakhoondi A, Beyer C, Sharifzadeh M.,"Sedative effects of Iranian Artemisia annua in mice: Possible benzodiazepine receptors involvement." Pharm Biol. 2011 May 10;
11. ^ Cumming JN; Ploypradith P; Posner GH (1997). "Antimalarial activity of artemisinin (qinghaosu) and related trioxanes: mechanism(s) of action". Adv. Pharmacol. 37: 253–97. PMID 8891104. 
12. ^ Gary H. Posner & Paul M. O’Neil (2004). "Knowledge of the Proposed Chemical Mechanism of Action and Cytochrome P450 Metabolism of Antimalarial Trioxanes Like Artemisinin Allows Rational Design of New Antimalarial Peroxides". Acc. Chem. Res. 37 (6): 397–404. doi:10.1021/ar020227u. PMID 15196049. 

External links

• Scientific information about the plant
• University of Washington article regarding anti-cancer properties
• Anamed.net Charity that trains people in the Tropics to cultivate Artemisia annua and to use their harvest in the form of tea to treat malaria and other diseases, as practiced in China for centuries.
• Distribution of Artemisinin in Artemisia annua
• Project to improve artemesinin yield at the University of York (UK)