title: In vitro evaluation of the antiviral properties of Shilajit and investigation of its mechanisms of action.
abstract: BACKGROUND
  Shilajit, a herbomineral substance exuded from rocks in steep mountainous regions, has been used for thousands of years by the Indian Ayurvedic and Siddha systems of traditional medicine to relieve ailments and enhance quality of life. Although a large number of therapeutic properties have been ascribed to Shilajit, its therapeutic potential is still largely unexplored by modern research and many of its claimed bioactivities lack scientific validation. The present study was undertaken to investigate the antiviral activity of Shilajit against a panel of viruses including herpes simplex type 1 and 2 (HSV-1, HSV-2), human cytomegalovirus (HCMV), human respiratory syncytial virus (RSV), human rotavirus (HRV), and vesicular stomatitis virus (VSV).
  
  
  METHODS
  The antiviral activity of Shilajit was assayed in vitro by plaque reduction and virus yield assays and the major mechanism of action was investigated by virucidal and time-of-addition assays.
  
  
  RESULTS
  Shilajit exhibited a dose-dependent inhibitory activity against HSV1, HSV2, HCMV, and RSV infectivity in vitro (EC50 values: 31.08μg/ml, 12.85μg/ml, 34.54μg/ml, and 30.35μg/ml, respectively), but was inactive against HRV and VSV. Humic acid, a constituent of Shilajit, displayed the same spectrum of activity. Partial virus inactivation and interference with virus attachment were both found to contribute to the antiviral activity of Shilajit.
  
  
  CONCLUSIONS
  The results of the present study demonstrate that Shilajit is endowed with broad, yet specific, antiviral activity in vitro and constitutes a natural source of antiviral substances. Further work remains to be done to assess its efficacy in vivo.
authors: Department of Clinical and Biological Sciences, University of Torino, Orbassano, 10043 Torino, Italy.
authors: Valeria
authors: V
authors: Cagno
authors: Department of Clinical and Biological Sciences, University of Torino, Orbassano, 10043 Torino, Italy.
authors: Manuela
authors: M
authors: Donalisio
authors: Department of Clinical and Biological Sciences, University of Torino, Orbassano, 10043 Torino, Italy.
authors: Andrea
authors: A
authors: Civra
authors: Dipartimento di Scienza e Tecnologia del Farmaco, Università degli Studi di Torino, Via P. Giuria 9, I-10125 Torino, Italy.
authors: Cecilia
authors: C
authors: Cagliero
authors: Dipartimento di Scienza e Tecnologia del Farmaco, Università degli Studi di Torino, Via P. Giuria 9, I-10125 Torino, Italy.
authors: Patrizia
authors: P
authors: Rubiolo
authors: Department of Clinical and Biological Sciences, University of Torino, Orbassano, 10043 Torino, Italy. Electronic address: david.lembo@unito.it.
authors: David
authors: D
authors: Lembo
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D002522:Chlorocebus aethiops; D006801:Humans; D006812:Humic Substances; D008519:Medicine, Traditional / Q000379:methods; D008903:Minerals / Q000494:pharmacology*; D011788:Quality of Life; D012116:Resins, Plant / Q000494:pharmacology*; D014709:Vero Cells; D014780:Viruses / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D006812:Humic Substances; D008903:Minerals; D012116:Resins, Plant; C045109:mumie
keywords: Antiviral; Ayurvedic medicine; Humic acid; Mechanism of action; Shilajit; Virus