Ficus religiosa L. bark extracts inhibit human rhinovirus and respiratory syncytial virus infection in vitro

Ethnopharmacological relevance Ficus religiosa L. is one of the most relevant members of the family of Moraceae . It is the most sacred tree of South Asia, and it is used in traditional Ayurvedic and Unani medicine to cure respiratory disorders like cough, wheezing and asthma. Some studies were performed to investigate the anti-asthmatic potential of F. religiosa bark, leaves and fruit extracts but none of them tested their antiviral activity against viruses responsible for the exacerbation of wheezing and asthma. Aim of the study The present study was undertaken to investigate the antiviral activity of F. religiosa L. extracts against respiratory viruses such as human respiratory syncytial virus (RSV) and human rhinovirus (HRV). Materials and methods The antiviral activity of F. religiosa L. was tested in vitro by plaque reduction and virus yield assays and the major mechanism of action was investigated by virus inactivation and time-of-addition assays. Results F. religiosa L. methanol bark extract was the most active against HRV with an EC 50 of 5.52 µg/mL. This extract likely inhibited late steps of replicative cycle. Water bark extract was the most active against RSV with an EC 50 between 2.23 and 4.37 µg/mL. Partial virus inactivation and interference with virus attachment were both found to contribute to the anti-RSV activity. Replication of both viruses was inhibited in viral yield reduction assays. Conclusions The results of the present study demonstrate that F. religiosa L. is endowed with antiviral activity against RSV and HRV in vitro . Further work remains to be done to identify the active components and to assess the therapeutic potential in vivo .