Anti-viral Activities of Oroxylum indicum Extracts on Chikungunya Virus Infection

Chikungunya virus (CHIKV) is a re-emerging mosquito-borne alphavirus that poses a threat to human worldwide. Driven by the lack of approved medication and vaccination, research on anti-Chikungunya agents has received great attention. In an effort to determine potential inhibitor of CHIKV, this study aimed at investigating the potential anti-viral activity of Oroxylum indicum extracts towards CHIKV-infected Vero cells. The virucidal, pre- and post-treatment effects of O. indicum were evaluated, using the maximum non-toxic dose of O. indicum methanol and aqueous extracts as determined by cytotoxicity assay. The viral inhibitory effect was assessed by the morphological changes of Vero cells and further confirmed by plaque assay. Both methanol and aqueous extracts of O. indicum had similar cytotoxicity in Vero cells. Interestingly, the virucidal effect of O. indicum aqueous extract revealed a significant reduction on the viral titre (p < 0.05). The prophylactic effect of aqueous extract was demonstrated when the pre-treated cells exhibited a significant anti-CHIKV activity (p < 0.05). However, methanol extract of this plant exerted an anti-viral activity against CHIKV only to a certain extent. Therefore, the aqueous extract of this plant has a potential to inhibit the virus and acts as prophylactic agent against CHIKV. Further studies however are needed to substantiate the finding and to determine the important compound of this plant as well as the mechanism of action in treating CHIKV infection.