Fig. 1

Perilla and sage contain water-soluble heat-stable components active against SARS-CoV-2 in vitro replication. A Scheme of the experimental setup for the in vitro analysis of therapeutic effects against SARS-CoV-2. B Representative dose-response curves of SARS-CoV-2-infected Vero E6 cells (2000 PFU per well) after treatment with aqueous infusions of coriander, perilla, or sage. Upper panel shows the effect on SARS-CoV-2 replication. Lower panel depicts the effect on HSV-1 replication. SARS-CoV-2 replication was analyzed at 20 h p.i. by icELISA, HSV-1:GFP replication was determined at 48 h p.i. by quantification of fluorescence. Data are expressed as relative change in infectivity compared to the untreated control. Each condition was analyzed in triplicate. See Additional file 1 for individual data values and “Methods” section and Additional file 2: Fig. S1 for details. The comparison of the herb-treated samples of SARS-CoV-2 to the untreated controls by one-way ANOVA showed for all dilutions of coriander no significance and for all dilutions of perilla and sage significance. The perilla- and sage-treated conditions of SARS-CoV-2 were also compared to the corresponding coriander-treated condition (same dilution) and these results are depicted in the diagram. *, p < 0.05. **, p < 0.01. ***, p < 0.001. The comparison of the herb-treated samples of HSV-1 to the untreated controls showed for all dilutions of all tested herbs no significance. C, D Visualization of SARS-CoV-2 infection upon treatment with herbal infusions. Vero E6 cells were infected (MOI 0.1) and treated (1/10 dilution) as shown in A. α-S mAb and a Cy2-coupled secondary antibody were used for immunofluorescence staining (green). Nuclei were counterstained with DAPI (blue). E Representative dose-response curves of SARS-CoV-2-infected Vero E6 cells (2000 PFU per well) after treatment (as shown in A) with aqueous infusions of coriander, perilla, sage, or SARS-CoV-2 convalescent serum (serum 6 from[26]. with mid-high 50% neutralization titer of 256). Each condition was analyzed in triplicate. See Additional file 1 for individual data values. The perilla- and sage-treated conditions were compared to the corresponding NAbs-treated condition (same dilution) by one-way ANOVA. **, p < 0.01. ***, p < 0.001