Prophylactic administration of Withania somnifera extract increases host resistance in Listeria monocytogenes infected mice

Int Immunopharmacol. 2006 Oct;6(10):1535-42. doi: 10.1016/j.intimp.2006.03.016. Epub 2006 Apr 27.


In this study, we demonstrated that Withania somnifera L. extract (WSE) protects mice from a lethal dose of Listeria monocytogenes when administered prophylactically at 100, 250 and 500 mg/kg for 10 days, with survival rates up to 30%. These doses also prevented the myelosuppression and the splenomegaly caused by a sublethal infection with L. monocytogenes, due to increased numbers of granulocyte-macrophage progenitors (CFU-GM) in the bone marrow. Investigation of the production of colony-stimulating factors (CSFs) revealed increased colony-stimulating activity (CSA) in the serum of normal and infected mice pre-treated with WSE. Further studies to investigate the levels of interferon-gamma (INF-gamma) and lymphocyte cell proliferation were undertaken. We observed dose-dependent increases in cell proliferation and in the levels of INF-gamma in mice infected with L. monocytogenes and treated with WSE. All together, our results suggest that WSE indirectly modulates immune activity and probably disengages Listeria-induced suppression of these responses by inducing a higher reserve of myeloid progenitors in the bone marrow, proliferation of lymphocytes and increased INF-gamma levels.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Proliferation / drug effects
  • Disease Models, Animal
  • Granulocyte-Macrophage Colony-Stimulating Factor / immunology
  • Interferon-gamma / immunology
  • Listeria monocytogenes* / growth & development
  • Listeriosis / immunology
  • Listeriosis / microbiology
  • Listeriosis / pathology
  • Listeriosis / prevention & control*
  • Lymphocytes / cytology
  • Lymphocytes / drug effects
  • Lymphocytes / immunology
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Plant Extracts / isolation & purification
  • Plant Extracts / therapeutic use
  • Spleen / cytology
  • Spleen / drug effects
  • Spleen / immunology
  • Withania / chemistry*


  • Plant Extracts
  • Interferon-gamma
  • Granulocyte-Macrophage Colony-Stimulating Factor