Artemisia annuaL. extracts inhibit thein vitroreplication of SARS-CoV-2 and two of its variants

Abstract

SARS-CoV-2 (Covid-19) globally has infected and killed millions of people. Besides remdesivir, there are no approved small molecule-based therapeutics. Here we show that extracts of the medicinal plant, Artemisia annua L., which produces the antimalarial drug artemisinin, prevents SARS-CoV-2 replication in vitro. We measured antiviral activity of dried leaf extracts of seven cultivars of A. annua sourced from four continents. Hot-water leaf extracts based on artemisinin, total flavonoids, or dry leaf mass showed antiviral activity with IC50 values of 0.1-8.7 μM, 0.01-0.14 μg, and 23.4-57.4 μg, respectively. One sample was >12 years old, but still active. While all hot water extracts were effective, concentrations of artemisinin and total flavonoids varied by nearly 100-fold in the extracts and antiviral efficacy was inversely correlated to artemisinin and total flavonoid contents. Artemisinin alone showed an estimated IC50 of about 70 μM, and antimalarial artemisinin derivatives artesunate, artemether, and dihydroartemisinin were ineffective or cytotoxic at elevated micromolar concentrations. In contrast, the antimalarial drug amodiaquine had an IC50 = 5.8 μM. The extracts had minimal effects on infection of Vero E6 or Calu-3 cells by a reporter virus pseudotyped by the SARS-CoV-2 spike protein. There was no cytotoxicity within an order of magnitude of the antiviral IC90 values. Results suggest the active component in the extracts is likely something besides artemisinin or is a combination of components acting synergistically to block post-entry viral infection. Further studies will determine in vivo efficacy to assess whether A. annua might provide a cost-effective therapeutic to treat SARS-CoV-2 infections.

Modeling of SARS-CoV-2 Treatment Effects for Informed Drug Repurposing

“…ART as the main component of A. annua (sweet wormwood) extract has not been studied in SARS-CoV-2. Nair et al reported an antiviral effect in Vero E6 cells of artesiminin on SARS-CoV-2 with an EC 50 of 19.8 µg/ml ( 70 µM) (Nair et al, 2021). Studies suggest that artemisinin interferes with viral entry by interaction with the spike protein (Sehailia and Chemat, 2020), but it also affects postentry steps of infection (Cao et al, 2020b;Nair et al, 2021).…”

In vitroefficacy of Artemisia extracts against SARS-CoV-2

“…[17] Other groups reported similar findings concerning pure synthetic artemisinin derivatives [25] and whole A. annua plant material. [18] Reports that teas made from A. annua and A. afra plants, [19] as well as Covid-Organics, a drink made from A. annua leaves and Ravensara aromatica in Madagascar, [20] have been used throughout Africa. Our earlier observation that A. annua extracts can inhibit SARS-CoV-2 in vitro prompted us to test whether such extracts can indeed inhibit coronaviruses.…”

“…In addition to pure, semi-synthetic substances, Artemisia teas and plant material have been explored for use to treat different diseases. [14] A. annua extract had shown anti-viral activity in vitro against SARS-CoV in 2005 [15] and SARS-CoV-2 (EC50 value: 2.5 µg/mL) [16] [18]. Standardized A. annua extracts with high artemisinin content are currently being studied in an ongoing phase 2 clinical trial against COVID- 19 [17].…”

Artemisia annuahot-water extracts show potent activityin vitroagainst Covid-19 variants including delta

“…Effective and approved small molecule-based therapeutics are still lacking. Recently, we showed that hot-water extracts of dried leaves of seven cultivars of the medicinal plant, Artemisia annua L., used for millennia to treat malaria fever (Hsu, 2006) and sourced from four continents, prevented SARS-CoV-2 replication in vitro (Nair et al, 2021). Recently, anti-SARS-CoV-2 efficacy of A. annua extracts was independently confirmed (Zhou et al, 2021).…”