Potential roles of medicinal plants for the treatment of viral diseases focusing on COVID-19: A review

The whole world is entangled by the coronavirus disease (COVID-19) pandemic caused
by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), people are
dying in thousands each day, and without an actual medication, it seems not possible
for the bringing this global health crisis to a stop. Natural products have been in constant
use since ancient times and are proven by time to be effective. Crude extract or
pure compounds isolated from medicinal plants and/or herbs such as Artemisia annua,
Agastache rugosa, Astragalus membranaceus, Cassia alata, Ecklonia cava, Gymnema sylvestre,
Glycyrrhizae uralensis, Houttuynia cordata, Lindera aggregata, Lycoris radiata,
Mollugo cerviana, Polygonum multiflorum, Pyrrosia lingua, Saposhnikoviae divaricate,
Tinospora cordifolia etc. have shown promising inhibitory effect against coronavirus.
Several molecules, including acacetin, amentoflavone, allicin, blancoxanthone, curcumin,
daidzein, diosmin, epigallocatechin-gallate, emodin, hesperidin, herbacetin,
hirsutenone, iguesterin, jubanine G, kaempferol, lycorine, pectolinarin, phloroeckol,
silvestrol, tanshinone I, taxifolin, rhoifolin, xanthoangelol E, zingerol etc. isolated from
plants could also be potential drug candidates against COVID-19. Moreover, these
could also show promising inhibitory effects against influenza-parainfluenza viruses,
respiratory syncytial virus, severe acute respiratory syndrome (SARS), and Middle
East respiratory syndrome coronavirus (MERS-CoV). Here, we have reported 93 antiviral
drug candidates which could be a potential area of research in drug discovery.