Immunostimulatory properties of the major protein from the stem of the Ayurvedic medicinal herb, guduchi (Tinospora cordifolia)

Abstract

Ethnopharmacological relevance: Guduchi (Tinospora cordifolia), a widely used plant in folk and Ayurvedic systems of medicine is well known for its immunomodulatory activity; however, the presence of an immunomodulatory protein (ImP) in guduchi has not been investigated.

Materials and methods: Guduchi ImP was purified from dry stem powder extract by anion-exchange chromatography on Q-Sepharose. Characterization of guduchi ImP was performed by SDS-PAGE, periodic acid-Schiff staining, HPLC, and immunochemical analyses. Immunostimulatory activity was assessed by lymphocyte proliferation and macrophage activation assays. Fresh guduchi stem/leaf, guduchi satwa and guduchi capsules were also analyzed for the presence of guduchi ImP.

Results: Guduchi ImP was purified to homogeneity from dry stem powder extract (~150 mg protein per 100 g guduchi stem powder) as a single chain acidic protein (25 kDa) without glycans; it was noticeably absent in guduchi leaf. Guduchi satwa and guduchi capsule preparations also lacked this protein. Guduchi ImP showed ~3-fold mitogenic activity compared to untreated murine splenocytes in the 1-10 μg/mL concentration range; 5-7-fold increase in mitogenic activity was seen in the case of murine thymocytes vs. control. The purified protein also induced nitric oxide production from macrophages present in isolated murine peritoneal exudates cells. Guduchi ImP displays enhanced phagocytosis of yeast cells by macrophages. Guduchi ImP does not possess hemagglutination activity (towards rabbit and human erythrocytes of all blood groups) indicating that the immunomodulatory protein is not a lectin.

Conclusions: The confirmation of an immunomodulatory protein in guduchi stem showing lymphoproliferative and macrophage-activating properties reinforces the rationale of the use of guduchi preparations in several Ayurvedic medicines for immunomodulation. To our knowledge, this is the first report of an immunomodulatory protein isolated from guduchi.