Norbergenin, an O-demethylated derivative of bergenin, can be isolated from rhizomes of Bergenia stacheyi.
Norbergenin shows anti-arthritic activity through modulation of Th1/Th2 cytokine balance, and it inhibits the production of proinflammatory Th1 cytokines (IL-2, IFN-γ and TNF-α) while as potentiate anti-inflammatory Th2 cytokines (IL-4 and IL-5) in the peripheral blood of adjuvant-induced arthritic balb/c mice.[1]
Norbergenin inhibits bovine adrenal tyrosine hydroxylase (TH) activity by 29.0% and 53.4% at a concentration of 20 μg/mL, and exhibited noncompetitive inhibition of TH activity with the substrate L-tyrosine. [2]
Norbergenin shows moderate antioxidant activity (IC50 13 μM in DPPH radical scavenging; 32 μM in superoxide anion scavenging). [3]
Reference:
[[1] Nazir N, et al. J Ethnopharmacol. 2007 Jun 13;112(2):401-5.
[2] Zhang YH, et al. Phytother. Res. 2003 Sep;17(8):967-9.
[3] Takahashi H, et al. Bioorg. Med. Chem. 2003 Apr 17;11(8):1781-8.