ABSTRACT
Due to lack of reliable therapy and insufficient available vaccines against SARS-CoV-2, researchers are looking for promising and effective therapy in substances that are already available. The objective of the current study is to investigate whether the herbal preparation Cystus Pandalis.. (CPE) has in vitro antiviral properties against SARS-CoV-2. CPE has already proved to be effective against several other viruses. At the Fraunhofer Institute for Cell Therapy and Immunology (IZI), cell cultures treated with Cystus Pandalis.. extract were infected with SARS-CoV-2, and the reduction in the infection rate was evaluated by comparing focus-forming units. An almost complete reduction in the CPE infection rate was observed at concentrations of greater than 15.6 ..g/ml with a calculated EC50 (mean effective concentration) of 1.94 ..g/ml. The mechanism of action of this extract may be based on the highly polymeric polyphenols that envelop certain viral epitopes, whereby CPE acts as an entry inhibitor. The high in vitro activity of CPE seems to make it a reasonable candidate for prophylaxis against SARS-CoV-2.