Antiviral screening of Egyptian traditional aromatic and medicinal plants against SARS-CoV-2

BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a significant respiratory pathogen that caused the COVID-19 pandemic with global mortality and morbidity. The emergence of SARS-CoV-2 poses a significant challenge for pandemic control efforts, including widespread screening, the development of effective antiviral therapeutics, and the repurposing of FDA-approved drugs granted emergency use authorization for COVID-19 treatment.ObjectiveThis study aims to screen extracts and fractions from various Egyptian aromatic and medicinal plants, traditionally used to treat multiple diseases, including viral infections, for their antiviral activity. The investigation further evaluates the potential biological effects of these extracts/fractions against SARS-CoV-2.Materials and methodsTwelve commonly used aromatic and medicinal plants were collected, and their extracts were prepared using various extraction methods. Following cytotoxicity assessment in Vero-E6 cells, the extracts were evaluated for antiviral activity against SARS-CoV-2. A series of in-vitro assays were conducted to characterize the antiviral properties of the extracts and their fractions, with the aim of elucidating their mechanisms of action on viral replication. The half-maximal cytotoxic concentration 50 (CC50) and half-maximal inhibitory concentration 50 (IC50) values were determined using crystal violet staining and plaque reduction assays, which measured viral replication. Additionally, viral RNA copy number was conducted to assess the antiviral efficacy of each extract.Results and conclusionThese findings indicated that methanolic extracts and their various solvent fractions exhibited antiviral activity, with inhibition percentages ranging from 0 to 88.2%. Among the sixty extracts/fractions tested of the selected plants, only twelve demonstrated significant antiviral effects against SARS-CoV-2, with inhibition ranges between 68% and 88%. The methanol extracts and the n-hexane, dichloromethane, and ethyl acetate fractions derived from Eucalyptus camaldulensis (Eucalyptus), Ficus carica (Fig), Ocimum basilicum (Basil), Olea europaea (Olive), and Ziziphus spina-christi (Christ’s thorn) effectively inhibited SARS-CoV-2 replication. This study compiles evidence supporting the antiviral potential of several Egyptian aromatic and medicinal plants, highlighting their promise as alternative therapeutic agents for the management and control of COVID-19.