Immunomodulatory activity of isoflavones isolated from Iris germanica (Iridaceae) on T‐lymphocytes and cytokines

Abstract

The immunomodulatory activities of two isoflavones, 5,7-dihydroxy-6,4′-dimethoxyisoflavone (irisolidone) (1) and 5,4′-dihydroxy-6,7-methylenedioxyisoflavone (irilone) (2) isolated from Iris germanica (Iridaceae) is reported. Their influence on production of T-lymphocytes (CD4+ and CD8+ cells) and T-cell cytokines, namely Th1: IL-2, IFN-γ and Th2: IL-4 and IL-5 in a dose-dependent manner was studied by flow cytometric method in Balb/c mice. Oral administration of drugs at doses of 0.1–0.8 mg/kg per oral dose showed 1 to possess stimulatory activity on T-cells and Th1 cytokine production, while as 2 acted as an immunosuppressant for both cells and cytokines. The methylated products of 1 and 2 showed a similar trend to that of their parent compounds but their activity was drastically decreased revealing the importance of free phenolic groups for their immunomodulating activities. Copyright © 2008 John Wiley & Sons, Ltd.