Immunomodulatory activity of isoflavones isolated from Iris kashmiriana: Effect on T-lymphocyte proliferation and cytokine production in Balb/c mice

This study deals with the evaluation of immunomodulatory action of a new isoflavone isonigricin (1) and first report isoirisolidone (2) isolated from rhizomes of Iris kashmiriana. Flowcytometric method was employed to study their effect on production of T-lymphocytes (CD4+ and CD8+ T-cells) and T-cell cytokines (IL-2, IL-4 and IFN-γ) in a dose-dependant manner. Drugs at doses of 0.025 to 0.8 mg/kg per oral dose showed compound 1 to possess immunosuppressant activity on T-cells as well as cytokines, while compound 2 acted as immunostimulator for both cells and cytokines. However, their methylated products viz. 1OMe and 2OMe exhibited stimulatory effect on interleukins under study and suppressive effect on production of T-lymphocytes and IFN-γ. The oral LD50 in mice was observed to be more than 200 mg/kg body weight. Such a difference in their activity is the manifestation of the position and nature of substituents present on isoflavonoidal skeleton and demonstrates the potential of these isolates as prospective immunomodulatory agents.