Artemisia annua L. hot-water extracts show potent activity in vitro against Covid-19 variants including delta

Abstract

Ethnopharmacological relevance: For millennia, Artemisia annua L. was used in Southeast Asia to treat "fever". This medicinal plant is effective against multiple pathogens and is used by many global communities as a source of artemisinin derivatives that are first-line drugs to treat malaria caused by Plasmodium parasites.

Aim of the study: The SARS-CoV-2 (Covid-19) global pandemic has killed millions and evolved numerous variants, with delta being the most transmissible to date and causing break-through infections of vaccinated individuals. We further queried the efficacy of A. annua cultivars against new variants.

Materials and methods: Using Vero E6 cells, we measured anti-SARS-CoV-2 activity of dried-leaf hot-water A. annua L. extracts of four cultivars, A3, BUR, MED, and SAM, to determine their efficacy against five infectious variants of the virus: alpha (B.1.1.7), beta (B.1.351), gamma (P.1), delta (B.1.617.2), and kappa (B.1.617.1).

Results: In addition to being effective against the original wild type (WT) WA1, A. annua cultivars A3, BUR, MED, and SAM were also potent against all five variants. IC₅₀ and IC₉₀ values based on measured artemisinin content ranged from 0.3 to 8.4 μM and 1.4-25.0 μM, respectively. The IC₅₀ and IC₉₀ values based on dried leaf weight (DW) used to make the tea infusions ranged from 11.0 to 67.7 μg DW and 59.5-160.6 μg DW, respectively. Cell toxicity was insignificant at a leaf dry weight of ≤50 μg in the extract of any cultivar.

Conclusions: Results suggest that oral consumption of A. annua hot-water extracts (tea infusions) could potentially provide a cost-effective therapy to help stave off the rapid global spread of these variants, buying time for broader implementation of vaccines.

Keywords: Artemisinin; Covid-19; Delta variant; Gamma variant; Kappa variant; SARS-CoV-2.