ABSTRACT
Introduction: COVID-19 is an infectious disease caused by the SARS-CoV-2, which severely affects the morbidity of people living with non-communicable diseases. Therefore, the Herbal Medicine Research Centre, Institute for Medical Research has taken the initiative to search for plant extracts and phytoconstituents with potential anti-SARS-CoV-2 properties in vitro. Material(s) and Method(s): The antiviral activities of potential plant-derived candidates against SARS-CoV-2 infection in Vero-E6 cells were assessed. The two steps viral induced-cytopathic effect (CPE) screening approach was used. Firstly, the SARS-CoV-2 was exposed with single doses (10 mug/mL or muM) of plant extracts and compounds after which the extracts and compounds with >=20% viral inhibitory activities were evaluated for dose-response antiviral activities. The dose-response antiviral activity for each extract and compound was quantitatively analyzed via a dose response curve using the Graphpad Prism software. Result(s) and Conclusion(s): From more than 60 plant extracts and compounds screened against the SARS-CoV-2 infection in vitro, at single dose exposure, 8 plant extracts and compounds showed >20% inhibition. Dose response analysis identified three plant extracts and one compound with potent antiviral activity (EC50<=10 mug/mL or muM) and high selectivity (SI>=10) towards the SARS-CoV-2. One of the extracts with potent anti-SARS-CoV-2 activity was derived from the E. longifolia plant, a Malaysian medicinal plant. Further evaluation on the efficacy of this plant's extract and compounds in SARS-CoV-2 infected human lung cells and a COVID- 19 animal model is warranted.