Artemisinin

Artemisinin is a compound from the sweet wormwood plant, Artemisia annua, that rapidly kills the parasites causing malaria. The Chinese scientist Tu Youyou discovered it in the 1970s and shared the 2015 Nobel Prize in Physiology or Medicine for the work.

In 1967 the Chinese government launched Project 523 to find new malaria drugs. Tu Youyou's team screened traditional medicines and found that extracts of sweet wormwood were active, a plant described in a fourth-century text. By switching to a lower-temperature extraction, they obtained a potent compound in 1971 and purified artemisinin. The drug was tested on patients and then used widely from the 1980s.

Artemisinin contains an unusual peroxide bridge. Inside the parasite, which digests hemoglobin in red blood cells and releases iron-containing heme, the bridge is activated and forms reactive radicals that damage proteins. This explains why it acts so fast against the blood stages of Plasmodium falciparum. To slow resistance it is given with partner drugs as an artemisinin combination therapy, the standard treatment recommended by the World Health Organization.

Plant harvests fluctuate, so scientists engineered baker's yeast to make the precursor artemisinic acid in a project led by Jay Keasling, an example of metabolic engineering and synthetic biology. Partial resistance, linked to mutations in the kelch13 gene, appeared in Southeast Asia and has also been found in parts of Africa, which makes it a case of growing antimicrobial resistance. The drug works on apicomplexan parasites.

• Malaria — the disease it treats
• Plasmodium falciparum — the main parasite targeted
• Antimicrobial Resistance — a growing threat to its use