Pyropia yezoensis Extract Attenuates Osteoarthritis Progression In Vitro and In Vivo

Osteoarthritis (OA), a degenerative disease characterized by cartilage degradation and inflammation, occurs due to trauma caused by external stimuli or cartilage aging. Pyropia yezoensis is a red alga that belongs to the Porphyra family and is consumed as food in Asia, especially Korea, Japan, and China. P. yezoensis contains various bioactive substances, including carotenoids, flavonoids, and vitamins, that exert anti-inflammatory, antioxidant, and anti-photoaging effects. In the present study, the anti-osteoarthritic effects of 30% fermented alcohol extract of P. yezoensis (30% FEPY) on interleukin-1 beta (IL-1β)-stimulated chondrocytes and a destabilization of the medial meniscus (DMM)-induced OA rat model were investigated. The results showed that pretreatment with 30% FEPY significantly reduced the IL-1β-induced expression of inflammatory factors (e.g., inducible nitric oxide synthase and cyclooxygenase-2) and cartilage-degrading enzymes [matrix metalloproteinase (MMP) 1, MMP3, MMP13, a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) 4, and ADAMTS5], which was analyzed using Griess reaction, enzyme-linked immunosorbent assay, and Western blot analysis. The anti-osteoarthritic effects of 30% FEPY, which were mediated through mitogen-activated protein kinase and nuclear factor kappa-light-chain-enhancer of activated B cell signaling, were analyzed using Western blot analysis. In an in vivo study, Safranin O staining and immunohistochemistry analysis revealed that treatment with 30% FEPY significantly increased cartilage degradation and collagen type II protein expression in the DMM group. These findings collectively suggest that 30% FEPY is a promising candidate for alleviating OA progression and developing new therapeutic drugs.