Anti-viral assay of flavonoids against DENV-2 intracellular replication. Foci forming unit reduction assay (FFURA) was used to evaluate the in vitro anti-dengue virus activities of flavonoids after viral adsorption (a) and the respective DENV-2 RNA copies were quantified using qRT-PCR (b). The percentages of foci reduction (% RF) were calculated relative to the untreated controls maintained in parallel. Data from triplicate assays were plotted using Graph Pad Prism Version 5 (Graph Pad Software Inc., San Diego, CA. USA).