Apple polyphenols exhibits chondroprotective changes of synovium and prevents knee osteoarthritis

Apple polyphenols (AP) have strong antioxidant and anti-inflammatory properties. We examined the effects of AP on the progression of osteoarthritis (OA) AP was administered to surgically-induced OA model rats for 4 or 8 weeks. This treatment suppressed inflammation and oxidative stress in the synovium, resulting in a decrease in the OA severity score, and the expression of tumor necrosis factor (TNF)-α and matrix metalloproteinase (MMP)-13 in the synovium. It was suggested that long-term administration of AP may be effective for the treatment of OA. In addition, superoxide dismutase (SOD) activity was enhanced in serum samples by AP. AP or its constituent procyanidin B2 (PC) were added to HIG-82 synoviocytes. The results showed that AP enhanced cell proliferation and hyaluronan production. This indicates that AP may improve synovial conditions in OA and suppress OA progression. These effects may be attributed to the antioxidant and anti-inflammatory properties of AP. •Apple polyphenols (AP) have strong antioxidant and anti-inflammatory properties.•The effects of AP on the progression of osteoarthritis (OA) is studied.•AP suppresses inflammation and oxidative stress in the synovium.•Administration of AP may be effective to treat OA.•Superoxide dismutase (SOD) activity in serum was enhanced by AP.