Abstract:
The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), known to cause the
disease COVID-19, was declared a pandemic in early 2020. The objective of this review
was to collate information regarding the potential of plants and natural products to inhibit
coronavirus and targets associated with infection in humans and to highlight known
drugs, which may have potential activity against SARS-CoV-2. Due to the similarity in the
RNA genome, main proteases, and primary host receptor between SARS-CoV and
SARS-CoV-2, a review was conducted on plants and secondary metabolites, which have
shown activity against SARS-CoV. Numerous scientific reports on the potential of plants
and secondary metabolites against SARS-CoV infection were found, providing important
information on their possible activity against SARS-CoV-2. Based on current literature, 83
compounds have been identified with the potential to inhibit COVID-19. The most
prominent selectivity was found for the alkaloid, lycorine, the lignan, savinin, and the
abietane terpenoid, 8-beta-hydroxyabieta-9(11),13-dien-12-one with selectivity index
values greater than 945, 667, and 510, respectively. Plants and their secondary
metabolites, with activity against targets associated with the SARS-CoV infection, could
provide valuable leads for the development into drugs for the novel SARS-CoV-2. The
prospects of using computational methods to screen secondary metabolites against
SARS-CoV targets are briefly discussed, and the drawbacks have been highlighted.
Finally, we discuss plants traditionally used in Southern Africa for symptoms associated
with respiratory viral infections and influenza, such as coughs, fever, and colds. However,
only a few of these plants have been screened against SARS-CoV. Natural products hold
a prominent role in discovering novel therapeutics to mitigate the current COVID-19
pandemic; however, further investigations regarding in vitro, in vivo, pre-clinical, and
clinical phases are still required.
