Artemisinin -  a compound extracted from the herb Artemisia annua L. 

Artemisinin is a compound extracted from the plant Artemesia annua L. (sweet wormwood, also known as the Chinese herbal Qinghao). Artemisinin (C₁₅H₂₂O₅ ) is a sesquiterpene lactone. Artemesia annua has been used in China since AD 341 to treat febrile illness. In 1971, the active ingredient, artemisininin, was identified and isolated.  

Derivatives of artemisinin have been synthesized. These include: dihydroartemisinin (DHA), artemether, artesunate, arteether, and artelinic acid.  These compounds have been packaged in different forms: tablets, capsules, suppositories and injectibles.

Mechanism of Action

The artemisinin molecule contains two oxygen atoms linked together in what is known as an ‘endoperoxide bridge’, which could react with an iron atom to form free radicals. Artemisinin is toxic to malaria parasites because the parasite contains a high amount of iron in the form of heme molecules. 

Free radicals cause macromolecular damages and kill the parasites. Artemisinin has been used as an antimalaria in more than two million patients. 

Rapid-growth abnormal cells sequester relatively large amounts of iron, mainly in the form of holotranferrin. Artemisinin has been shown to cause rapid and extensive damage to these abnormal cells and to have relatively low toxicity to normal cells.

Toxicity in Large Animals.

When artemisinin was tested with monkeys, they showed no toxicity after they received up to 292 mg/kg of artemether over one to three months. High doses of artemisinin can produce neurotoxicity such as gait disturbances, loss of spinal and pain response, respiratory depression, and ultimately cardiopulmonary arrest in large animals.

 Healthy Volunteers. 250-mg artemisinin and artesunate were used in a pharmacokinetic studies. Both pharmaceutical forms were well-tolerated and no undesirable side effects were observed. 

Mice. Artemisininin is virtually non-toxic (LD50 = 4228 mg/kg orally administered to mice) and without carcinogenicity.  

Pharmacokinetics.

The healthy human voluntarily oral administrated 250 mg tablets of artemisinin and artesunate. For Artemisinin, the mean maximum drug concentration C_max = 0.36 microgram/ml,  appearance half life T_1/2  = 0.62 hr, distribution half life t_1/2 á = 2.61 hr, decline half-life t_1/2 â = 4.34 hr, total area under the concentration-time curve (AUC) = 1.19 microgram.hg/ml, its main metabolite, dihydroartemisinin was measurable in the plasma. For artesunate, half lives were much shorter.