Specific plant terpenoids and lignoids possess potent antiviral activities against SARS coronavirus

In this study, groups of phytocompounds were evaluated for their effects on anti-severe acute respiratory syndrome associated coronavirus (SARS-CoV) activities using a cell-based assay measuring SARS-CoV-induced cytopathogenic effect (CPE) on Vero E6 cells. Among 221 compounds tested, 10 diterpenoids (1-10), 2 sesquiterpenoids (11-12), 2 triterpenoids (13-14), 5 lignoids (15-19), curcumin (20) and reference controls, niclosamide (21) and valinomycin (22), exhibited potent activities at concentrations between 3.3 and 10 μM. Concentrations to inhibit 50% Vero E6 cell proliferation (CC50) and viral replication (EC50) of the 22 compounds were measured. The selective index values (SI = CC50/EC50) of compounds 1, 5, 6, 8, 14, and 16 were determined at 58, >510, 111, 193, 180 and >667, respectively, indicating a strong anti-SARS viral activity. Betulinic acid (13) and savinin (16) were observed to be competitive inhibitors for SARS-CoV 3CL protease with Ki values = 8.2 ± 0.7 and 9.1 ± 2.4μM, respectively. Our findings suggest that specific abietane-type diterpenoids and lignoids can exhibit strong anti-SARS-CoV effects that may serve as novel lead compounds for future development of anti-SARS therapeutics.
Lie-Fen Shyur

Wen, C. C., Kuo, Y. H., Jan, J. T., Liang, P. H., Wang, S. Y., Liu, H. G., Lee, C. K., Chang, S. T., Kuo, C. J., Lee, S. S., Hou, C. C., Hsiao, P. W., Chien, S. C., Shyur, L. F.*, and Yang, N. S.* (2007) Specific plant terpenoids and lignoids possess potent antiviral activities against SARS coronavirus Journal of Medicinal Chemistry