Drug repurposing for the treatment of COVID-19: Pharmacological aspects and synthetic approaches

Graphical abstract
Highlights • The repositioning of approved drugs is a promising approach for treating COVID-19. • Several approved drugs have shown anti-SARS-CoV-2 activity and are discussed herein. • In this review, the synthetic approaches toward such molecules was highlighted. • The mechanisms of action and pharmacological properties of such drugs is discussed.
In December 2019, a new variant of SARS-CoV emerged, the so-called acute severe respiratory syndrome coronavirus 2 (SARS-CoV-2). This virus causes the new coronavirus disease (COVID-19) and has been plaguing the world owing to its unprecedented spread efficiency, which has resulted in a huge death toll. In this sense, the repositioning of approved drugs is the fastest way to an effective response to a pandemic outbreak of this scale. Considering these facts, in this review we provide a comprehensive and critical discussion on the chemical aspects surrounding the drugs currently being studied as candidates for COVID-19 therapy. We intend to provide the general chemical community with an overview on the synthetic/biosynthetic pathways related to such molecules, as well as their mechanisms of action against the evaluated viruses and some insights on the pharmacological interactions involved in each case. Overall, the review aims to present the chemical aspects of the main bioactive molecules being considered to be repositioned for effective treatment of COVID-19 in all phases, from the mildest to the most severe.