Abstract: Received: 14 February 2022 Revised: 21 March 2022 Accepted: 25 March 2022 DOI: 10.1002/ptr.7463 LETTER TO THE EDITOR In vitro antiviral activity against SARS-CoV-2 of common herbal medicinal extracts and their bioactive compounds For raw herbal materials, ethanol crude extracts were prepared To the Editor, The coronavirus SARS-CoV-2 spread all around the world, leading to by maceration of powdered plant with EtOH at room temperature. A an unprecedented pandemic. Up to date, some effective treatments 10 g of dried powder was used for 100 ml of EtOH. The solvent of have been highlighted to treat the symptoms, but not to cure the the resulting filtrates was evaporated at low temperature (<40 C) COVID-19 disease. At least, some well-known medicines have been under reduced pressure and dissolved in DMSO. Commercially man- proposed, but have rapidly become the subject of some controversy, ufactured extracts were readily dissolved in DMSO for the assay. such azithromycin Cells culture and virus preparation were performed as previously (Maisonnasse et al., 2020; Okour, Al-Kofahi, & Austin, 2020) and iver- described by our team (Ledoux et al., 2022). The antiviral and cyto- mectin (Zaidi & Dehgani-Mobaraki, 2022). As no treatments were con- toxic experiments were performed in triplicate in 96-well plates, as sidered neither safe nor efficient enough, new coronavirus vaccines previously reported (Ledoux et al., 2022). On day one, cells grown in obtained conditional marketing authorisation. The public health crisis 10 cm standard tissue culture dishes (Falcon, Becton-Dickinson) of COVID-19 led to countries around the world promoting massive were trypsinized and counted using a Cedex XS cell analyser (Roche vaccination programs. However, one can observe that the results are Innovatis). A 100 μl of cell suspension containing 2,000 Vero E6 via- not fulfilling the hopes and expectations concerning virus transmission ble cells was seeded in a 96-well tissue culture plate (Falcon, as hydroxychloroquine combined or not (Franco-Paredes, 2022), while the data concerning pharmacovigilance Becton-Dickinson) and grown overnight. On day two, 50 μl of are still in process. In this context, research should focus on the hin- extracts (or pure compound) were added to the wells of the 96-well drances of implementing cost-effective and safe drugs, as well as pre- plate containing confluent cells with a final range of concentration ventive health products. Plants extracts and natural isolated from 50 to 1.5 μg/ml in duplicate. A 50 μl of virus suspension or compounds which are already used as medicines, dietary supplements virus-free medium was added, respectively, to determine the ant- or preventive health products, can offer a cost-effective way to fight iviral activity or the cytotoxicity. The antiviral activity was against COVID-19, especially since they have proven to be safe to use. established regarding the minimal concentration, which was able to In accordance with this strategy, we have then evaluated different protect the cells from the viral cytopathic effects, observed through plants and extracts for their antiviral activity against SARS-CoV-2 a microscope, compared to the untreated control on day five post- strain. The selection of plant species included in this antiviral screening infection. was based on either their use in common winter ailments, on the previ- Regarding the 17 plants..