Effect of Alpinia oxyphylla extract in vitro and in a monosodium iodoacetate-induced osteoarthritis rat model

Background: Osteoarthritis (OA) affects the articular cartilage and subchondral bone of synovial joints and induces proinflammatory and anti-inflammatory pathway dysregulation, leading to pain. This study evaluated the anti-inflammatory and antiosteoarthritis effects of Alpinia oxyphylla extract (AOE) in vitro and in vivo. Methods: The anti-inflammatory effect of AOE was evaluated in vitro in lipopolysaccharide (LPS)-treated RAW264.7 cells. The antiosteoarthritis effect of AOE was investigated in a monosodium iodoacetate (MIA)-induced rat model of OA. Rats were orally administered AOE (150 mg/kg or 300 mg/kg) or the positive control drug indomethacin (1 mg/kg) 3 days before MIA injection and once daily for 21 days thereafter. Results: AOE significantly decreased the production of nitric oxide (NO, 68.2%), prostaglandin E2 (PGE2, 92.8%), interleukin-1 beta (IL-1 beta, 77.2%), interleukin-6 (IL-6, 39.9%), and tumor necrosis factor-alpha (TNF-alpha, 20.7%) and the activation of extracellular signal-regulated kinase (ERK), Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) in LPS-treated RAW264.7 cells at a dose of 100 mu g/ml. In addition, AOE attenuated joint pain, suppressed proinflammatory cytokine and mediator production and inhibited cartilage degradation in the MIA-induced rat OA model. Conclusion: These results demonstrate that AOE exerts potent anti-inflammatory effects and may be a useful therapeutic candidate against OA.