Researchers in the United States have shown that extracts of so-called fragrant herb Artemisia annua prevention of reproduction of acute respiratory coronavirus (SARS-CoV-2) – the agent responsible for the 2019 pandemic of coronavirus infection (COVID-19).
Also known as “Sweet wormwood,” Artemisia annua (A. annua) an Asian herb that produces the antimalarial agent artemisinin.
Now, researchers at Columbia University in New York, Washington University, and the Worcester Polytechnic Institute have confirmed that a hot water leaf A. annua extracts based on artemisinin, total flavonoids, or dried leaf mass show antiviral activity against SARS-CoV-2.
“This is the first report on the anti-SARS-CoV-2 efficacy of hot water extracts of a wide range of cultivars of A. annua has come from four continents, ”said Pamela Weathers and colleagues. “Further studies will test the effectiveness of in vivo to determine whether A. annua they may provide cost-effective treatment to treat SARS-CoV-2 infections. ”
A pre-printed version of the paper is available on the bioRxiv * server, while the article is subject to peer review.
Antiviral activity of the herb has been previously demonstrated
The medicinal plant A. annua and the artemisinin it produces has been used safely for the treatment of several diseases, particularly malaria, for over 2,000 years.
One study carried out in 2005 showed that the herb has antiviral effects against SARS-CoV-1 – the agent responsible for the 2002 to 2003 SARS revolution.
Moreover, there are both A. annua Plant and artemisinin have been shown to reduce levels of the inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) in vivo.
“These impact molecules can be complex in the‘ cytokine storm ’suffered by many SARS-CoV-2 patients,” said Weathers and the team.
What did the current study cover?
The team assumed powdered dried leaves of A. annua it may represent a safe and cost-effective method for the treatment of SARS-CoV-2 infections.
The researchers tested the effect of segments from seven A. annua cultivars obtained from four different continents on SARS-CoV-2 propagated in Vero E6 cells. They also evaluated a correlation between antiviral efficacy with artemisinin, total flavonoid content, and dry leaf mass.
All sections showed anti-SARS-CoV-2 activity. The IC50 values (concentration of drug inhibiting 50% of the target) were calculated based on artemisinin, total flavonoid content or dry leaf mass ranging from 0.1 to 8.7µM, 0.01 to 0.14µg and 23.4-57.4µg, separately.
One sample obtained in 2008 still showed anti-SARS-CoV-2 activity that was comparable to the recently harvested cultivar samples.
This suggests that the ubiquitous operating principle is different A. annua cultivars and is chemically stable during long-term dry storage of room temperature, the researchers say.
Antiviral efficacy has been remarkably associated with artemisinin and total flavonoid content
Although the hot water extracts were effective, antiviral efficacy was remarkably associated with artemisinin and total flavonoid content.
Analysis of artemisinin alone had estimated IC50 around 70µM, and although the artemisinin derivative artemether showed efficacy at 1.23µM, it was cytotoxic at concentrations higher than this.
The artesunate derivatives and dihydroartemisinin were also ineffective at levels below 100µM.
In contrast, the conditionimaquine antimalarial drug had an IC50 of 5.8 µM.
In addition, a Spearman Rho study showed that the IC50 or IC90 values of the hot water extracts were not related to artemisinin or total flavonoid content.
The researchers also found that the extracts had little antiviral effects against pseudoviruses containing the spike protein SARS-CoV-2 – the main structure used by the virus to attach to and enter host cells. The team says this suggests that A. annua mainly inhibits SARS-CoV 2 infection by targeting a postoperative phase.
“The findings suggest that the active ingredient in the extracts appears to be something other than artemisinin or a combination of components working homogeneously to prevent post-entry viral infection,” he said. Weathers and colleagues.
Investigating the effects of dried foliage A. annua wear
To inspect a dried leaf A. annua (DLA) as a therapeutic treatment, Weathers consumed 3 grams of encapsulated DLA of the US cultivar, and the team monitored artemisinin as a marking molecule by extracting blood samples two and five hours later.
At two to five hours after injection, artemisinin levels were 7.04µg and 0.16 µg per mL of serum, respectively. At 2 h, this corresponded to serum artemisinin / mL of 2.35µg of artemisinin delivered with DLA per gram of DLA consumed.
The researchers say that while there is a clear need for human trials, the study suggests that consuming reasonable amounts of DLA may be a cost-effective treatment for SARS-CoV-2 infection.
“If clinical trials are successful after that, A. annua this could be a safe treatment that could be given worldwide at a reasonable cost and provide an alternative to vaccines, ”the team concluded.
* Important message
bioRxiv publish preliminary scientific reports that are not peer-reviewed and, therefore, should not be seen as final, guiding health-related clinical practice / behavior, or be treated as information established.