Sweet Wormwood

Extracts of sweet wormwood have been used for more than 2000 years in traditional Chinese herbal medicine as a cooling herb for fevers, a typical symptom of viral infections. Also known in Chinese as huang hua hao (modern) or qing hao (ancient), communities around the world use the plant as a medicinal tea for infectious microbial and viral diseases, especially malaria. It is also used in the treatment of jaundice, bacterial dysentery and in the treatment of wounds and haemorrhoids. 

The 2015 Nobel Prize in Physiology or Medicine was awarded to Professor Youyou Tu for her key contributions to the discovery of the sesquiterpene lactone artemisinin, a constituent of sweet wormwood. Artemisinin, and various semisynthetic derivatives of it, are among the most widely used malaria drugs in the world. It is a potent antimalarial that has significantly reduced the mortality rates for patients suffering from malaria. Tu searched ancient literature on herbal medicine in her quest to develop novel malaria therapies. The plant sweet wormwood turned out to be an interesting candidate and Tu developed a purification procedure which rendered the active agent, artemisinin, a drug that is remarkably effective against malaria. A clinical trial showed that a decoction of sweet wormwood effectively eliminated symptoms, and dramatically lowered parasite burden, in adults with chronic malaria with cure rates on average of 74% despite providing far lower levels of artemisinin than are used as an isolated drug. This suggests there is more to sweet wormwood than just artemisinin. The issue with isolating artemisinin is that the drug created is financially beyond the reach of most people suffering from malaria and the drug also raises the probability of generating drug resistance. Ongoing work is needed to identify all the synergistic compounds in sweet wormwood. 

In relation to this a 2021 in vitro study found that sweet wormwood extracts inhibited SARS-CoV-2 (the infectious substance of COVID-19) infection, and the active component(s) in the extracts is likely something besides artemisinin, or a combination of components that block virus infection at a step downstream of virus entry. In a 2023 in vitro study by some of the same researchers, sweet wormwood tea infusions continued to show efficacy against SARS-CoV-2 and its rapidly evolving variants including omicron. They urged testing of sweet wormwood to treat COVID-19 in clinical trials sooner rather than later. 

References

Kim WS, Choi WJ, Lee S, Kim WJ, Lee DC, Sohn UD, Shin HS, Kim W. Anti-inflammatory, Antioxidant and Antimicrobial Effects of Artemisinin Extracts from Artemisia annua L. Korean J Physiol Pharmacol. 2015 Jan;19(1):21-7. doi: 10.4196/kjpp.2015.19.1.21. Epub 2014 Dec 31. PMID: 25605993; PMCID: PMC4297758.

Nair MS, Huang Y, Fidock DA, Polyak SJ, Wagoner J, Towler MJ, Weathers PJ. Artemisia annua L. extracts inhibit the in vitro replication of SARS-CoV-2 and two of its variants. J Ethnopharmacol. 2021 Jun 28;274:114016. doi: 10.1016/j.jep.2021.114016. Epub 2021 Mar 12. PMID: 33716085; PMCID: PMC7952131.

Ekiert H, Świątkowska J, Klin P, Rzepiela A, Szopa A. Artemisia annua - Importance in Traditional Medicine and Current State of Knowledge on the Chemistry, Biological Activity and Possible Applications. Planta Med. 2021 Jul;87(8):584-599. doi: 10.1055/a-1345-9528. Epub 2021 Jan 22. PMID: 33482666.

Mueller MS, Runyambo N, Wagner I, Borrmann S, Dietz K, Heide L. Randomized controlled trial of a traditional preparation of Artemisia annua L. (Annual Wormwood) in the treatment of malaria. Trans R Soc Trop Med Hyg. 2004 May;98(5):318-21.

Yarnell E. Synergy in Herbal Medicines: Part 1. Journal of Restorative Medicine.2015 Dec 1;4(1):60-73

Nair MS, Huang Y, Fidock DA, Polyak SJ, Wagoner J, Towler MJ, Weathers PJ. Artemisia annua L. extracts inhibit the in vitro replication of SARS-CoV-2 and two of its variants. J Ethnopharmacol. 2021 Jun 28;274:114016. doi: 10.1016/j.jep.2021.114016. Epub 2021 Mar 12. PMID: 33716085; PMCID: PMC7952131.

Nair MS, Huang Y, Wang M, Weathers PJ. SARS-CoV-2 omicron variants are susceptible in vitro to Artemisia annua hot water extracts. J Ethnopharmacol. 2023 May 23;308:116291. doi: 10.1016/j.jep.2023.116291. Epub 2023 Feb 18. PMID: 36804200; PMCID: PMC9937997.