Anti-adenovirus activities of shikonin, a component of Chinese herbal medicine in vitro.

Radix Lithosperm eyrthrorhizon is a common prescription compound in traditional Chinese medicine. Shikonin is a major component of Radix Lithospermi and has various biological activities. We have investigated the inhibitory effect of shikonin on the growth of adenovirus type 3 (AdV3) in vitro. The antiviral function of shikonin against AdV3 and its virus inhibition ratio were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method (MTT). The expression of hexon protein in AdV3 was determined by immunofluorescence assay using laser scanning confocal microscopy (LSCM) and Western blot analysis. In addition, the rate of apoptosis in cells infected by AdV3 was determined by flow cytometry. Shikonin (0.0156-1 µM) inhibited growth of AdV3 in a concentration-dependent manner with a virus inhibition rate of 23.8-69.1%. Expression of hexon protein in AdV3 was higher in the virus control group than in the shikonin-treated groups as determined by immunofluorescence assay and Western blotting (p<0.05). The rate of shikonin-treated HeLa cell apoptosis had a statistically significant decrease with increasing concentration of drug (p<0.05). Our data demonstrate that shikonin possesses anti-AdV3 capabilities and that the potential antiviral mechanism might involve inhibiting the degree of apoptosis and hexon protein expression of AdV.