Specific Plant Terpenoids and Lignoids Possess Potent Antiviral Activities against Severe Acute
Respiratory Syndrome Coronavirus
In this study, 221 phytocompounds were evaluated for activity against anti-severe acute respiratory syndrome
associated coronavirus (SARS-CoV) activities using a cell-based assay measuring SARS-CoV-induced
cytopathogenic effect on Vero E6 cells. Ten diterpenoids (1-10), two sesquiterpenoids (11 and 12), two
triterpenoids (13 and 14), five lignoids (15-19), curcumin (20), and reference controls niclosamide (21)
and valinomycin (22) were potent inhibitors at concentrations between 3.3 and 10 µM. The concentrations
of the 22 compounds to inhibit 50% of Vero E6 cell proliferation (CC50) and viral replication (EC50) were
measured. The selective index values (SI ) CC50/EC50) of the most potent compounds 1, 5, 6, 8, 14, and
16 were 58, >510, 111, 193, 180, and >667, respectively. Betulinic acid (13) and savinin (16) were
competitive inhibitors of SARS-CoV 3CL protease with Ki values ) 8.2 ( 0.7 and 9.1 ( 2.4 µM, respectively.
Our findings suggest that specific abietane-type diterpenoids and lignoids exhibit strong anti-SARS-CoV
effects.