Evaluation of In vitro Antiviral Activity of Datura metel Linn. Against Rabies Virus

Objective: The soxhlet and cold extracts of Datura metel Linn. were evaluated for in vitro antirabies activity. Materials and Methods: Soxhlet and cold extraction method were used to extract Datura (fruit and seed) extracts. In vitro cytotoxicity assay was performed by 3‑(4,5‑dimethylthiazolyl‑2)‑2,5‑diphenyltetrazolium bromide assay. Based on the CC50 range, the in vitro antirabies activity of the extracts was screened by rapid fluorescent focus inhibition test and molecular method. Results: The Datura (fruit and seed) extracts were not cytotoxic below 5 mg/ml (CC50). Titer of 10−4 rabies virus challenge virus standard (RV CVS) (1 50% tissue culture infective dose [1 TCID50]) was obtained by RFFT method and the challenge dose of 10 TCID50 was used for antirabies assay. Datura fruit and seed (soxhlet and cold) extracts showed 50% inhibition of RV CVS at 2.5 mg/ml and 1.25 mg/ml (inhibitory concentration 50% [IC50]), respectively. The tested extracts showed selectivity index (CC50/IC50) ranging from 2 to 4. The viral RNA was extracted and real‑time reverse transcription‑polymerase chain reaction was performed which also revealed a 2‑fold reduction of viral load at 1.25 mg/ml of the Datura seed (soxhlet methanolic and cold aqueous) extracts. Conclusion: To the best of our knowledge, this is the first study of in vitro antiviral activity of D. metel Linn. against rabies virus. Datura seed extracts have a potential in vitro antirabies activity and, in future, can be further screened for in vivo activity against rabies virus in murine model.