In vitro screening of South African medicinal plants in the pursuit of anti-viral agents against SARS-CoV-2

The COVID-19 pandemic continues to be a global health concern despite numerous efforts being undertaken to curb it. This has necessitated the urgent need to seek more complementary tools, including drugs, to treat this disease. Inspired by the fact that natural products have historically served as a source of chemical scaffolds for development of drugs, the current study aims to interrogate South African biodiversity in search of novel anti-viral agents against SARS-CoV-2. A dual approach was adopted where in-silico screening and a rigorous criterion were used to select pure natural compounds and medicinal plants for the study. Compounds were phenotypically screened in-vitro against the main protease and spike protein of SARS-CoV-2. Using a high-throughput fractionation technique, twenty traditionally used plants were extracted and fractionated into semi-pure fractions using hyphenated analytical technologies for an accelerated screening approach.

Of the eight compounds screened, epigallocatechin gallate showed the most pronounced activity in the spike/ACE2 disruptive assay (IC₅₀ of 0.44 µg/ml), presenting some inhibition activity at 15 µg/ml in the whole-cell assays. From the twenty plant species screened, four demonstrated good activity (IC₅₀<10 µg/ml) in the disruption of the spike/ACE2 complex and inhibition of the main protease (>80% inhibition at 1 µg/ml). One species additionally exhibited activity in phenotypic screens with the active compound identified as punicalagin (>75% plaque reduction at 15 µg/ml). Our data motivates the continued interrogation of South African plants in the search of novel anti-SARS-CoV-2 agents.

Publikationsverlauf

Artikel online veröffentlicht:
13. Dezember 2021