Artemisia annua

Scientific name(s)/brand name(s)/common name(s)

Artemisia annua L., also known as sweet wormwood, sweet annie, sweet sagewort and annual wormwood (Chinese: qīnghāo), is a common type of wormwood that is native to temperate Asia, but naturalized throughout the world, and that belongs to the family of Asteraceae. It has fern-like leaves, bright yellow flowers, and a camphor-like scent. Glandular structures (trichomes) producing a wide range of bioactive compounds (mostly terpenoids) can be found on the surface of leaves, stems and flowers.

Ingredient(s)

The phytochemical composition of Artemisia annua has been reviewed in great detail by Bhakuni et al. 2. The most relevant compounds are sesquiterpenoids (ex. artemisinin), triterpenoids, flavonoids (polymethoxylated flavonoids), chromenes 2 and essential oil components.

Besides Artemisia annua itself, this summary also reviews current literature on artesunate, dihydroartemisinin and artemether. Artesunate, dihydroartemisinin and artemether are semi-synthetic derivatives of artemisinin. Much more research has been published on the effect of these compounds than on artemisinin itself. Arteether, another semisynthetic derivative that has been used in antimalarial treatment has not been the focus of anticancer research to date.

Application and dosage

There is no documented safe or effective dose for the possible use of Artemisia annua derived products for the treatment of cancer in adults or children. However, information on dosage from traditional use of herbal preparations for other indications is available 3. In addition, artemisinin and its semisynthetic derivatives are used in antimalarial treatment in artemisinin-based combination therapies 4.

History

Sweet wormwood was used by Chinese herbalists in ancient times to treat specific fevers, but had fallen out of common use, until it was rediscovered in 1970 when the Chinese Handbook of Prescriptions for Emergency Treatments (340 AD) was recovered. This ancient pharmacopeia contained a recipe for a tea from the dried leaves of A. annua to be used in case of specific fevers. In 1971, scientists demonstrated that the plant extracts had antimalarial properties in primate models 5.

Mechanism of anti-cancer action

Artemisinin, the natural endoperoxide of Artemisia annua, and its semisynthetic derivates dihydroartemisinin, arthemether, artheether and artesunate are considered to be the primary active constituents for antimalarial and anti-cancer activity 6-7. Also the polymethoxyflavanoids are indicated as important compounds with potential anticancer activity. Cancer cell lines show a differential sensitivity as well as resistance to this group of compounds. Different genes which influence the sensitivity or the resistance to treatment have been identified. These genes could potentially function as markers indicating the expected efficacy of a clinical therapy 8-9. In contrast to popular belief that the cytotoxic activities would only be due to the non-specific generation of reactive oxygen species (ROS), it has become clear that artemisinin-related endoperoxides additionally have various specific molecular targets and can significantly influence the expression of key regulatory proteins of the cell cycle 6-7,9-10. Artemisinin-related endoperoxides were found to significantly inhibit angiogenesis and also to induce apoptosis 6,11. Iron plays a crucial role in the cytotoxic activities of artemisinin-related endoperoxides through the generation of both ROS and carbon-centered radicals. In general, the addition of iron has been shown to enhance both the cytotoxicity and selectivity of the treatment, but not in all cell lines 6-11.

Alleged indications

Apart from malaria, Artemisia annua is also used in cases of fever, headaches, infections and inflammations 12.

There is no data available on the prevalence of use of Artemisia annua in the treatment of cancer.

Legal issues

There are no Artemisia annua derived drugs that are approved for cancer treatment.

Cost(s) and expenditures

Prices available on the internet for artesunate range between $0.30 and $0.70 for a 100mg tablet or capsule.