Immunomodulatory effect of bergenin and norbergenin against adjuvant-induced arthritis--a flow cytometric study.

Bergenin (1), a C-glycoside of 4-O-methyl gallic acid, isolated from rhizomes of Bergenia stracheyi (Saxifragaceae) and its O-demethylated derivative norbergenin (2), prepared from 1, are reported to show anti-arthritic activity through possible modulation of Th1/Th2 cytokine balance. Flow cytometric study showed that the oral administration of 1 and 2 at doses of 5, 10, 20, 40 and 80 mg/kg per oral dose inhibit the production of proinflammatory Th1 cytokines (IL-2, IFN-gamma and TNF-alpha) while as potentiate anti-inflammatory Th2 cytokines (IL-4 and IL-5) in the peripheral blood of adjuvant-induced arthritic balb/c mice. This shows the potential Th1/Th2 cytokine balancing activity of 1 and 2 which is strongly correlated with their anti-arthritic activity. At similar dose levels, the effect of 2 was found to be more than that of 1. The oral LD(0) for 1 and 2 was more than 2000 mg/kg body weight of the mice.