Chondroprotective Effects of Ulva prolifera on Osteoarthritis through MAPKs Signaling Inhibition

Osteoarthritis (OA) is a typical degenerative disease that mainly appears in the elderly aged 65 and over. OA is characterized by inflammation and decomposition of the cartilage matrix due to irreversible wear and tear. Ulva prolifera, a green macroalgae species, contains polysaccharides, amino acids, polyunsaturated fatty acids, and polyphenols, which are major active components responsible for anti-inflammatory and antioxidant effects. This study evaluated the chondro-protective effect of 30% prethanol extract of U. prolifera (30% PeUP). Rat primary chondrocytes were pre-treated with 30% PeUP for 1 h before interleukin-1β (10 ng/mL) stimulation. The production of nitrite, prostaglandin E₂ (PGE₂), collagen type II (Col II), and aggrecan (ACAN) were detected by Griess reagent and enzyme-linked immunosorbent assay. The protein expression levels of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, matrix metalloproteinase (MMP)-1, MMP-3, MMP-13, a disintegrin and metalloproteinase with thrombospondin (ADAMTS)-4, ADAMTS-5, and mitogen-activated protein kinases (MAPKs) (extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase, and p38) were assessed by western blot. Thirty percent of PeUP significantly inhibited the expression of nitrite, iNOS, PGE₂, COX-2, MMP-1, MMP-3, MMP-13, ADMATS-4, and ADMATS-5 in interleukin (IL)-1β-stimulated chondrocytes. Moreover, 30% PeUP decreased the IL-1β-induced degradation of Col II and ACAN. Additionally, 30% of PeUP suppressed IL-1β-induced phosphorylation of MAPKs. Therefore, 30% PeUP is a potential therapeutic agent to mitigate OA progression.