Comparative Anti-Infectious Bronchitis Virus (IBV) Activity of (-)-Pinene: Effect on Nucleocapsid (N) Protein

In the present study, anti-IBV (infectious bronchitis virus) activities of (-)pinenes were studied by MTT assay, as well as docking and molecular dynamic (MD) simulations. The CC50 values of (-)-alpha-pinene and (-)-beta-pinene were above 10 mM. And the maximum noncytotoxic concentrations (TD0) of (-)-alpha-pinene and (-)-beta-pinene were determined as 7.88 +/- 0.06 and 6.09 +/- 0.31 mM, respectively. The two compounds were found to inhibit IBV with an IC50 of 0.98 +/- 0.25 and 1.32 +/- 0.11 mM. The MTT assay showed that the inhibitions of (-)-pinenes against IBV appear to occur moderately before entering the cell but are much stronger occur after penetration of the virus into the cell. Molecular simulations indicated that (-)-alpha-pinene and (-)-beta-pinene specifically interact with the active site which is located at the N terminus of phosphorylated nucleocapsid (N) protein, with the former being more potent than the latter. The binding energies of them are -36.83 and -35.59 kcal mol(-1), respectively. Results presented here may suggest that (-)-alpha-pinene and (-)-beta-pinene possess anti-IBV properties, and therefore are a potential source of anti-IBV ingredients for the pharmaceutical industry.