Assessment of potency of PC‑complexed Ocimum sanctum methanol extract in embryonated eggs against Influenza virus (H1N1)

Background: Despite of new vaccines, the threat of influenza infection persists. In addition, availability, cost, duration of protection rendered and effectiveness of vaccines additional to the need of effective drug therapy makes influenza a challenge, which the globe faces. Traditionally used herbs and their decoctions are used for ages to cure symptoms similar to influenza. Tulsi or Ocimum sanctum is one of these major herbs used for influenza‑like disease treatment. We attempted to explore a new methodology for assessing phosphatidyl choline (PC)‑complexed O. sanctum methanol extract in embryonated vaccine quality eggs model. Materials and Methods: The PC‑complexed O. sanctum methanol extract was prepared and standardized using High‑Performance Liquid Chromatography (HPLC). (Data not provided here) Nine to 11 days embryonated eggs were inoculated with the virus and drug mixture and then harvested to perform a hemagglutination (HA) test on the allantoic fluid. The experiments were performed at three different concentrations of ursolic acid with various virus concentration and dose levels of drugs. The HA titer was calculated from all experiments and observed for any inhibition of virus. Results: In initial experiments, matrix method for drug and virus concentration was employed. It was observed that the drug exhibited some response for 3log EID50 (egg infective dose) in few samples at 1:2 HA titer, but no response was observed at 4log EID50. In subsequent experiment, all the virus titers from 7log EID50 to 2log EID50 demonstrated positive HA titer of 1:64. However, the drug failed to exhibit any significant inhibition at any level of demonstrable virus titer. At all the concentrations, O. sanctum extracts were found to be safe. Conclusion: The embryonated egg model may be utilized further to screen other drugs, which possess direct inhibitory properties like neuraminidase inhibition, and O. sanctum does not inhibit the influenza virus in this model at the given concentration.