Protective effect of ethyl acetate fraction from Semen sojae germinatum, the processed sprout of Chinese black soybean, on rat experimental osteoarthritis

BACKGROUND: Our previous in vitro study reported that the ethyl acetate fraction (EAF) of Semen sojae germinatum (SSG), the processed sprout of Chinese black soybean, possessed the potent anti-inflammatory and chondroprotective properties. The aim of the present work was to verify the in vivo antiosteoarthritic effect of EAF from SSG on a rat osteoarthritis (OA) model . METHODS: A classical rat OA model was surgically induced by anterior cruciate ligament transaction (ACLT). The OA rats were intra-articularly administered EAF from SSG for 8 weeks. The cartilage and synovial tissues were stained with hematoxylin and eosin (HE) to observe the histopathological changes. Safranin O/fast green staining was used to assess the glycosaminoglycan content in cartilage tissue sections. The expression of type II collagen and matrix metalloproteinase (MMP)-13 in cartilage was measured by immunohistochemistry. The apoptotic chondrocytes in the cartilage sections were detected using TUNEL assay. The concentrations of interleukin (IL)-1β and tumor necrosis factor (TNF)-ɑ in synovial fluid were determined using ELISA. RESULTS: Intra-articular administration of EAF from SSG well retained the structure and superficial layer of cartilage tissues, ameliorated cartilage lesion and the degradation of cartilage matrix, including proteoglycan and type II collagen, induced by ACLT operation. The ACLT-induced upregulation of MMP-13 expression in the cartilage tissues was resisted by EAF from SSG. Moreover, EAF from SSG inhibited the ACLT-induced chondrocyte apoptosis. Compared to OA model group, the inflammatory status of synovial membrane was improved, the levels of inflammatory cytokines IL-1β and TNF-ɑ in synovial fluid were decreased in rats administrated with EAF from SSG. CONCLUSION: These data suggested that EAF from SSG displayed in vivo protective effect on OA development via preventing the degeneration of articular cartilage, inhibiting chondrocyte apoptosis and suppressing synovial inflammation.