Sweet wormwood (Artemisia annua) is a shrub with fern-like leaves and bright yellow flowers. It's a member of the Asteraceae family and usually flowers between August and September. This plant thrives in direct sunlight and enjoys a variety of soil conditions. Native to Asia, it is now found throughout the world, especially in temperate zones at altitudes between 1000 and 1500 meters.
Artemisinin is the Key Antimalarial Constituent
In traditional Chinese medicine sweet wormwood is called "qinghoa" and used for the management of fevers and bleeding. It is also used for conditions of the digestive tract like flatulence and diarrhea. In modern allopathic medicine, a chemical component of this plant has shown astounding activity in the treatment of malaria. This constituent is a sesquiterpene lactone called "artemisinin" and it appears to kill and inhibit the growth of malaria-causing protozoa like Plasmodium falciparum.
Rush to Produce Artemisinin for Treating Malaria
The Chinese discovered artemisinin's anti-malarial activity in the 1970s but restricted its export for several decades. Apparently, this was due to distrust of the European-US pharmaceutical industry and the possibility it would attempt to patent constituent derivatives. Now, throughout the world, artemisinin is part of first-line therapy in the treatment of active malarial infection. About one million people die each year from malaria. Thus, manufacturers are scrambling to find sustainable and cost effective ways of manufacturing this compound to meet world demand. The common approach is to nurture sweet wormwood plantations. Less conventional approaches involve the direct creation of artemisinin using genetically engineered organisms like yeast and bacteria.
Efficacy of Herbal Material Remains Unsubstantiated
Controversy exists regarding use of crude plant materials for treating malaria. Conventional thought holds that since artemisinin is not water soluble, a tea from it will be ineffective. Sweet wormwood plants vary in their artemisinin content, ranging from 0.05 - 0.21 %. Some proprietary varieties of the species may consistently claim 1.1%.
Combination Therapy Mandatory to Prevent Drug Resistance
When dosing artemisinin, it is important to remember that it is not used for malaria prevention (prophylaxis), and is only used in combination with another antimalarial (combination therapy). Combination therapy is a strategy recommended by many health organizations to combat resistance. Several derivatives of artemisinin now exist:
- artemether
- artesunate
- arteether
These derivatives are generally taken with another antimicrobial in a weight-dependent dose lasting three to six days. There is concern regarding neurotoxicity as an adverse effect of these derivatives, especially when they are injected intramuscularly. The challenge is that malaria itself is often associated with neurotoxic signs and symptoms.
Resources:
Duke. J. A. and Ayensu. E. S. Medicinal Plants of China Reference Publications, Inc. 1985 ISBN 0-917256-20-4
Heide, L. (2006). "Artemisinin in traditional tea preparations of Artemisia annua." Trans R Soc Trop Med Hyg 100(8): 802.
Stuart. Rev. G. A. Chinese Materia Medica. Taipei. Southern Materials Centre
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