Evaluation of antiviral activity of essential oil of Trachyspermum Ammi against Japanese encephalitis virus

Background: Japanese encephalitis is a leading form of viral encephalitis, prevalent mostly in South Eastern Asia caused by Japanese encephalitis virus (JEV). It is transmitted by the mosquitoes of the Culex sp. The disease affects children and results in 50% result in permanent neuropsychiatric disorder. There arises a need to develop a safe, affordable, and potent anti-viral agent against JEV. This study aimed to assess the antiviral activity of ajwain (Trachyspermum ammi: Umbellifereae) essential oil against JEV. Materials and Methods: Ajwain oil was extracted by distillation method and in vitro cytotoxicity assay was performed in vero cell line by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay method. JEV titer was determined by plaque assay and in vitro antiviral activity of ajwain oil was quantified by the plaque reduction neutralization test (PRNT). Results: Cytotoxic concentration of the oil was found to be 1 mg/ml by MTT assay. The titer of the virus pool was found to be 50× 107 PFU/ml. we observed 80% and 40% virus inhibition in 0.5mg/ml of ajwain oil by PRNT method in preexposure treatment and postexposure treatment (antiviral activity), respectively. Conclusion: Our data indicate ajwain oil has potential in vitro antiviral activity against JEV. Further, the active biomolecule will be purified and evaluated for anti-JEV activity and also to scale up for in vivo trial to evaluate the efficacy of ajwain oil in future.