One of two molecules for this week.
July 30, 2018
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Image of Artesunate 3D Image of Artesunate
Figure 1: Artemether
Image of Artesunate 3D Image of Artesunate
Figure 2: Artesunate

Artemisinin is a venerable malaria drug that was introduced more than 40 years ago. It was the Molecule of the Week for December 12, 2005.

Artemisinin is an excellent remedy for malaria. For many years, however, its supply has been unpredictable. The sole source of the drug is the sweet wormwood plant (Artemisia annua) that grows in Southeast Asia; but its production cycle is vicious. Farmers grow the plant only when prices are high; the inevitable oversupply lowers prices and production drops, raising prices again.

As a result, medicinal researchers sought to synthesize an artemisinin precursor that would ensure a constant supply of the drug at lower cost than agricultural artemisinin. Sanofi (Gentilly, France) developed a synthesis of artemether (Figure 1), which it commercialized in 2013. Unfortunately, the project failed because the semisynthetic artemisinin could not be produced less expensively than the farmed product.

Since then, drug researchers concentrated on improving the yield of artemisinin and its derivatives from A. annua. For example, the leaves of the plant contain as much dihydroartemisinic acid (DHAA) as artemisinin. Earlier this year, Kerry Gilmore and Peter H. Seeberger at Max Planck Institute of Colloids and Interfaces (Potsdam, Germany) reported that crude extracts of A. annua can be fed into a photochemical flow reactor to produce artemisinin, artemether, and a third active pharmaceutical ingredient, artesunate (Figure 2).

Artesunate turns out to be a particularly attractive malaria drug. It is much more water-soluble than artemisinin, so it can be taken by mouth* or by injection. It is safe and well-tolerated by adults and children. Its success has earned it a place in the World Health Organization's List of Essential Medicines.

*But overdoses can be harmful; see hazard information table.


Artemether hazard information

GHS classification**: acute toxicity,oral, category 4
H302—Harmful if swallowed Chemical Safety Warning

**Globally Harmonized System of Classification and Labeling of Chemicals. Explanation of pictograms.

Artesunate hazard information

GHS classification: acute toxicity,oral, category 4
H302—Harmful if swallowed Chemical Safety Warning
GHS classification: acute toxicity,dermal, category 4 
H312—Harmful in contact with skin Chemical Safety Warning
GHS classification: acute toxicity,inhalation, category 4
H332—Harmful if inhaled Chemical Safety Warning

Artemether fast facts

CAS Reg. No. 71963-77-4
Molar mass 298.37 g/mol
Empirical formula C16H26O5
Appearance White to pale yellow crystals or powder
Melting point 86–90 ºC
Water solubility 12 mg/L (est.)

Artesunate fast facts

CAS Reg. No. 88495-63-0
Molar mass 384.42 g/mol
Empirical formula C19H28O8
Appearance White crystals or powder
Melting point 140–142 ºC 
Water solubility 680 mg/L
Chemical Abstract Service - a division of ACS

Learn more about this molecule from CAS, the most authoritative and comprehensive source for chemical information.

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