Figure 2. Pre-treatment of curcumin strongly inhibited enveloped viruses, but does not affect plaque formation of enterovirus 71 (EV 71).

(A) 2,000 pfu of Pseudorabies virus (PRV), Japanese encephalitis virus (JEV), and Dengue virus serotype II (DVII) were pre-treated with 30 µM of curcumin for one hour and remaining viral infectivity was measured by standard plaque assay. To count plaque numbers, after one hour incubation, the mixture of virus and drug was further diluted into 10⁻¹, 10⁻², 10⁻³ with medium without serum followed by standard plaque assay. White spots indicate viral plaques. (B–C) To measure the effect of curcumin, 2,000 pfu of EV71, JEV, and influenza virus, strain PR8 were pre-treated with a serial dilutions of curcumin (30, 20, 10, 5, 1, 0.5, 0.1 µM to 0 µM) for one hour and the plaque formation ability was measured by standard plaque assay. Plaque formation ability of EV71 as not inhibited by curcumin, whereas infectivity of influenza viruses was strongly affected (B). Pre-treatment of curcumin inhibit plaque formation of JEV and Influenza to a similar extent, whereas EV71 remained unaffected (C). The results from Fig. 2C were plotted based on three independent experiments.