BACKGROUND/OBJECTIVESThe inhibitory effect of Hijikia fusiforme (HF) extracts on degenerative osteoarthritis was examined in primary cultured rat cartilage cells and a monosodium iodoacetate (MIA)-induced osteoarthritis rat model.MATERIALS/METHODSIn vitro, cell survival and the expression of matrix metalloproteinases (MMPs), collagen type I, collagen type II, aggrecan, and tissue inhibitor of metalloproteinases (TIMPs) was measured after H2O2 (800 µM, 2 hr) treatment in primary chondrocytes. In vivo animal study, osteoarthritis was induced by intra-articular injection of MIA into knee joints of rats, and then RH500, HFE250 and HFE500 were administered orally once a day for 28 days. To determine the anti-inflammatory effects of HFE, nitric oxide (NO), prostaglandin E2 (PGE2) expression were measured. In addition, real-time PCR was performed to measure the genetic expression of MMPs, collagen type I, collagen type II, aggrecan, and TIMPs.RESULTSIn the in vitro assay, cell survival after H2O2 treatment was increased by HFE extract (20% EtOH). In addition, anabolic factors (genetic expression of collagen type I, II, and aggrecan) were increased by HFE extract (20% EtOH). However, the genetic expression of MMP-3 and 7, known as catabolic factors were significantly inhibited by treatment with HFE extract (20% EtOH). In the in vivo assay, anabolic factors (genetic expression of collagen type I, II, aggrecan, and TIMPs) were increased by oral administration of HFE extract. However, the genetic expression of MMP-3 and 7, known as catabolic factors, and production of NO and PGE2 were significantly inhibited by treatment with oral administration of HFE extract.CONCLUSIONSHFE extract inhibited articular cartilage degeneration through preventing extracellular matrix degradation and chondrocyte injury.