Anti-dengue activity of Andrographis paniculata extracts and quantification of dengue viral inhibition by SYBR green reverse transcription polymerase chain reaction

BACKGROUND: Dengue virus is a leading cause of illness and death in the tropics and subtropics. As many as 400 million people are infected yearly. Dengue is caused by any one of four related viruses transmitted by mosquitoes. Currently, there is no vaccine to prevent infection with dengue virus and the most effective protective measures are those that avoid mosquito bites. When infected, early recognition and prompt supportive treatment can substantially lower the risk of medical complications and death. Nowadays, the search for natural plant products to fight against viral diseases has been increasing. AIMS AND OBJECTIVE: To test the anti-dengu viral activity of both ethanolic & aqueous extract of Andrographis paniculata. MATERIALS AND METHODS: In vitro antiviral activity were performed against dengue virus by the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method and SYBR green quantitative real-time polymerase chain reaction (PCR) method. Cytotoxicity was also evaluated by MTT. The dengue viral load (VL) inhibition in plant extracts was characterized by reverse transcription PCR (RT-PCR) analysis. RESULTS AND DISCUSSION: In this study, the maximum nontoxic dose (MNTD) of A. paniculata plant was determined by testing the ethanolic extracts against Vero cells in vitro. Antiviral assay based on cytopathic effects denoted by degree of inhibition upon treating DENV 1–4-infected Vero cells with MNTD of A. paniculata has the most antiviral inhibitory effects. These results were further verified with an in vitro inhibition assay using MTT and RT-PCR, in which 55%–97% of cell viability were recorded in DENV-1–4-infected cells in different duration. CONCLUSION: Ethanolic extracts treated with dengue VLs also showed a significant changes which were reflected in RT PCR assay.