Methanol extract of Dioscoreae Rhizoma inhibits pro-inflammatory cytokines and mediators in the synoviocytes of rheumatoid arthritis

Dioscoreae Rhizoma (MDR), the root of Dioscorea tokoro MAKINO, has been used for the treatment of arthritis, muscular pain and urinary diseases in oriental medicine. The present work evaluates a methanol extract of Dioscoreae Rhizoma (MDR). MDR did not show any cytotoxic effect on mouse lung fibroblast cells (mLFCs) or human fibroblast-like synovial cells (hFLSCs). However, it significantly reduced the proliferation of hFLSCs stimulated by interleukin-1beta (IL-1β) and tumor necrosis factor-alpha (TNF-α). MDR significantly inhibited the production of TNF-α and IL-1β as well as down-regulating the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in IL-1β- and TNF-α-stimulated hFLSCs. MDR also effectively reduced the level of reactive oxygen species (ROS) in these cells. Taken together, these findings provide evidence that MDR may be a candidate for the treatment of rheumatoid arthritis (RA).