Artemisia annua, also known as
Sweet Wormwood,
Sweet Annie,
Sweet Sagewort or
Annual Wormwood , is a common type of
wormwoodArtemisia is a large, diverse genus of plants with between 200 to 400 species belonging to the daisy family Asteraceae. It comprises hardy herbs and shrubs known for their volatile oils. They grow in temperate climates of the Northern Hemisphere and Southern Hemisphere, usually in dry or semi-dry...
that is native to temperate Asia, but naturalized throughout the world.
Characteristics
It has fern-like
leavesIn botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin. There is continued debate about whether the flatness of leaves evolved to expose the chloroplasts to more light or to increase the absorption of carbon dioxide. In...
, bright yellow
flowerA flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to mediate the union of male sperm with female ovum in order to produce seeds...
s, and a
camphorCamphor is a waxy, white or transparent solid with a strong, aromatic odor. It is a terpenoid with the chemical formula C
10H
16O. It is found in wood of the camphor laurel , a large evergreen tree found in Asia and also of Dryobalanops aromatica, a giant of the Bornean forests...
-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-pollinatedOutcrossing is the practice of introducing unrelated genetic material into a breeding line. It increases genetic diversity, thus reducing the probability of all individuals being subject to disease or reducing genetic abnormalities...
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
malariaMalaria is a vector-borne infectious disease caused by a eukaryotic protist of the genus Plasmodium. It is widespread in tropical and subtropical regions, including parts of the Americas, Asia, and Africa. Each year, there are approximately 350–500 million cases of malaria, killing between one and...
).
Extractions
In 1971, scientists demonstrated that the plant extracts had antimalarial activity in primate models, and in 1972 the active ingredient,
artemisininArtemisinin is a drug used to treat multi-drug resistant strains of falciparum malaria. The compound is isolated from the plant Artemisia annua. Not all plants of this species contain artemisinin. Apparently it is only produced when the plant is subjected to certain conditions, most likely biotic...
(formerly referred to as
arteannuin), was isolated and its chemical structure described. Artemisinin may be extracted using a low boiling point
solventA solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution.The most common solvent in everyday life is water. Most other commonly-used solvents are organic chemicals. These are called organic solvents...
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
sesquiterpeneSesquiterpenes are a class of terpenes that consist of three isoprene units and have the molecular formula C
15H
24. Like monoterpenes, sesquiterpenes may be acyclic or contain rings, including many unique combinations...
lactoneIn chemistry, a lactone is a cyclic ester which can be seen as the condensation product of an alcohol group -OH and a carboxylic acid group -COOH in the same molecule...
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. In In 2004, the Ethiopian Ministry of Health changed Ethiopia’s first line anti-malaria drug from Fansidar, a
SulfadoxineSulfadoxine is an ultra-long-lasting sulfonamide often used in combination with pyrimethamine to treat or prevent malaria....
agent which has an average 36% treatment failure rate, to CoArtem, an agent created from
A. annua and which is 100% effective when used correctly, despite a world-wide shortage at the time of the needed derivative from
A. annua.
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 cancerBreast cancer is a cancer that starts in the breast, usually in the inner lining of the milk ducts or lobules. There are different types of breast cancer, with different stages , aggressiveness, and genetic makeup. With best treatment, 10-year disease-free survival varies from 98% to 10%...
cells [Cancer Research 65.Dec 1, 2005] and some form of
prostateThe prostate is a compound tubuloalveolar exocrine gland of the male mammalian reproductive system. Females do not have prostate glands...
cancer, there have been exciting preclinical results against
leukemiaLeukemia is a cancer of the blood or bone marrow and is characterized by an abnormal proliferation of blood cells, usually white blood cells . Leukemia is a broad term covering a spectrum of diseases...
, 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 stressOxidative stress is caused by an imbalance between the production of reactive oxygen and a biological system's ability to readily detoxify the reactive intermediates or easily repair the resulting damage. All forms of life maintain a reducing environment within their cells...
in the cells of the parasite. Malaria is caused by the Apicomplexan,
Plasmodium falciparumPlasmodium falciparum is a protozoan parasite, one of the species of Plasmodium that cause malaria in humans. It is transmitted by the female...
, which largely resides in red blood cells and itself contains iron-rich
hemeA heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin...
-groups (in the from of
hemozoinHemozoin is a disposal product formed from the digestion of blood by some blood-feeding parasites. These hematophagous organisms such as Malaria parasites , Rhodnius and Schistosoma digest hemoglobin and release high quantities of free heme, which is the non-protein component of hemoglobin...
).
Other uses
In modern-day central
ChinaChina is a cultural region, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
, specifically
Hubei Province' is a central province of the People's Republic of China. Its abbreviation is 鄂 , an ancient name associated with the eastern part of the province since the Qin Dynasty. The name Hubei means "north of the lake", referring to Hubei's position north of Lake Dongting...
, 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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