Anti-viral effects of continuous treatment with flavonoids against DENV-2 replication. Foci forming unit reduction assay (FFURA) was used to evaluate the in vitro anti-dengue virus activities of the flavonoids. Cells were treated with the flavonoids at 5 h before infection and continuously treated with fresh flavonoids upto 4 days post infection (a). The respective DENV-2 RNA copy numbers were quantified using qRT-PCR (b). The percentages of foci reduction (% RF) were obtained by comparing against untreated controls maintained in parallel. Data from triplicate experiments were plotted using Graph Pad Prism Version 5 (Graph Pad Software Inc., San Diego, CA).