As the world desperately searches for weapons to fight the COVID-19 pandemic, more and more people are turning to an herbal remedy: artemisia annua. The sweet wormwort plant provides the key ingredient artemisinin for so-called artemisinin-based combination therapies (ACTs), which the World Health Organization (WHO) recommends as a first-line treatment against malaria.

Andry Rajoelina, one of Madagascar's most visible advocates, He has been touting COVID-19 Organics, an artemisinin-containing supplement developed by the Applied Research Institute of Madagascar. In May, he claimed that more than 20 other African countries had ordered the elixir.

Still, some people are reluctant to give up artemisia annua as a source of COVID-19 treatment. In April, Mateon Therapeutics, a California biotech company, announced in a press release that tests showed that artemisinin inhibited replication of SARS-COV-2, the novel coronavirus that causes COVID-19. Artemisinin and its derivative artesunate are also among a series of compounds being screened for the virus at the Liverpool School of Tropical Medicine, with results expected within weeks.

A consortium of Researchers in Germany and Denmark is testing whether artemisinin derivatives and extracts from the artemisia annae plant can prevent SARS-COV-2 from infecting human cells. "There is some evidence in the literature that these things have potential antiviral properties," said Kerry Gilmore of the Max Planck Institute for Colloids and Interfaces, a member of the consortium. For example, in 2005, Chinese researchers found that artemisia artemisia extract has some activity against SARS-CoV, the coronavirus that caused the outbreak of severe acute respiratory syndrome (SARS) in 2002-3 (Antiviral., DOI: 10.1016 / j. antiviral 2005.02.007). However, researchers have yet to identify the active compounds that might cause this effect or determine their mechanism of action on the coronavirus.

In its fight against malaria, artemisinin uses the parasite's taste for hemoglobin in the host's blood. When the parasite digests hemoglobin, it releases the iron porphyrin heme complex from the protein. Because the heme is toxic to the parasite, the organism usually converts the complex into a more benign crystalline form. "But artemisinin disrupts this heme detoxification pathway," says Paul O 'Neill, a pharmaceutical chemist at the University of Liverpool.

If artemisinin does have any effect on SARS-COV-2, says Harvard's Wirth, it may depend on an entirely different mechanism than the one it uses against malaria parasites.