Abstract :
Objective The mosquito transmitted dengue virus (DENV) the causative agent of dengue fever (DF) remains a significant public health burden in many countries. Thailand, along with many countries in Asia and elsewhere, has a long history of using traditional medicines to combat febrile diseases such as DF. Screening bioactive compounds from traditional medicines reported to have antipyretic or anti-inflammatory activity may lead to the development of potent antivirals. In this study oroxylin A (OA), a flavonoid derivative found in Oroxylum indicum (commonly called the Indian trumpet flower or tree of Damocles), was screened for antiviral activity towards DENV. Results Cytotoxicity analysis in BHK-21 cells showed a 50% cytotoxic concentration (CC.sub.50) of 534.17 [micro]M. The compound showed no direct virucidal activity towards DENV, and pre-treatment of cells had no effect on virus production. A deficit was seen in virus production when cells were post-infection treated with oroxylin A. Under conditions of post-infection treatment, the EC.sub.50 value was 201.1 [micro]M, giving a selectivity index (SI) value of 2.66. Accumulation of DENV E protein inside the cell was seen under conditions of post-infection treatment, suggesting that oroxylin A may exert some effects at the virus assembly/egress stages of the replication cycle. Keywords: Oroxylin A, Dengue virus, Antiviral compound