Promising medicinal plants as a starting point for clinical research into therapies for COVID-19: A literature review

Abstract

Background: The world community continues to tackle the life-threatening Coronavirus infection which has spread across the world. In times of pandemic, it is to be expected that people turn to those medicinal plants (MPs) commonly used to protect themselves against disease. Methods: To meet our objectives, we examined all documented findings about the antiviral activity of MPs as well as some other essential compounds, which may act as future research targets for treating Coronavirus (COVID-19). For this purpose, a range of electronic databases have been reviewed up until 15 November 2021: Medline via PubMed, Google Scholar, ScienceDirect and Scopus. Data on MPs that demonstrated one or more of these three actions were recorded, including the extraction method and plant part used, the chemical compounds present, the mechanism of action and the type of study. The compounds in some of these MPs responsible for these activities have also been discussed in the literature. Results: The following findings were obtained: 41 MPs with antiviral activities and 19 phytocompounds under clinical trials. The secondary metabolites with direct or indirect antiviral activity are mainly flavonoids, tannins, phenols, polysaccharides, terpenes, lectins, alkaloids and steroids. Conclusions: These informative data could constitute a starting point for further studies to validate antiviral activities in vivo, as well as meaningful efficacy in humans, for potential therapeutic agents for COVID-19 Keywords: Medicinal plants; Antiviral activity, Phytocompounds; Secondary metabolites, COVID-19 Therapy