Extract from Cistus × Incanus L. Pandalis also Effective Against “British” Alpha (B.1.1.7) and “South African” Beta (B.1.351) SARS-CoV-2 Variants

Abstract

Background: In previous studies, a special extract from Cistus × incanus L. Pandalis (Cystus Pandalis® extract) has already proven to be effective against SARS-CoV-2 in vitro. We assume that an effect was also likely against the new SARS-CoV-2 variants, like the “British” alpha variant (B.1.1.7) as well as against the “South African” beta variant (B.1.351). Methods: To verify this, we investigated the inhibition of the cytopathic effect (CPE) of the coronaviruses by the Cystus Pandalis® extract in a cell model with human intestinal cells (Caco-2). We inoculated viral pre-treated cells with the herbal extract (A), and we mixed pre-treated viruses with the herbal extract in the cell cultures (B). Result: We observed an almost complete inhibition of virus growth by Cystus Pandalis® extract at concentrations of more than 100 μg/ml. The calculated IC50 (mean inhibitory concentration) for the “British” alpha variant (B.1.1.7) as well as for the “South African” beta variant (B.1.351) is below 50 μg/ml. There was no significant difference in the results in the two different ways of treatment. Conclusion: Extract from Cistus × incanus L. Pandalis (Cystus Pandalis® extract) can prevent in in-vitro cell cultures infections with SARS-CoV-2. Due to the high in vitro activity against the new variants, it also appears reasonable in the future to use Cystus Pandalis® as prophylaxis against infections with SARS-CoV-2. A development of resistance is unlikely. People tolerate the extract very well. It has no significant side effects.