The Effect of the Prethanol Extract of Trifolium pratense Leaves on Interleukin-1β-Induced Cartilage Matrix Degradation in Primary Rat Chondrocytes

BACKGROUND: Osteoarthritis (OA) is a degenerative joint disease, characterized by cartilage degradation and inflammation. The proinflammatory cytokine, interleukin (IL)-1β, plays a crucial role in the pathogenesis of OA by inducing the release of other catabolic factors that contribute to cartilage degradation. Trifolium pratense L. (red clover) has been used as a medicinal plant in many countries and as a source of nutraceuticals to alleviate the symptoms of menopause. Ob-jectives: In this study, we aimed to evaluate the anticatabolic effect of 40% prethanol extract of T. pratense (40% PeTP) on IL-1β-stimulated chondrocytes. METHODS: Primary rat chondrocytes were pretreated with 40% PeTP for 1 h before stimulation with IL-1β (20 ng/mL). The production of nitrite, prostaglandin E2 (PGE2), and aggrecan was measured by using Griess reagent and ELISA. Protein expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, matrix metalloproteinase (MMP)-1, MMP-3, MMP-13, A disintegrin and metalloproteinase with thrombospondin motif (ADAMTS)-4, mitogen-activated protein kinase (MAPK), and the nuclear factor (NF)-κB p65 subunit was measured by using Western blotting. RESULTS: PeTP (40%) significantly inhibited the IL-1β-induced expression of nitrite, iNOS, PGE2, COX-2, MMP-1, MMP-3, MMP-13, and ADAMTS-4 in isolated primary rat chondrocytes. Furthermore, 40% PeTP decreased the IL-1β-induced degradation of aggrecan, the phosphorylation of MAPKs, and the nuclear translocation of the NF-κB p65 subunit. CONCLUSION: These results suggested that 40% PeTP has a chondroprotective effect on inflammation and may be a potential preventative agent for OA progression.