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Background/Aims: Osteoarthritis (OA) is a multifactorial disease that is associated with inflammation in joints. The purpose of the present study was to investigate the anti-inflammatory activity and mechanism of morin on human osteoarthritis chondrocytes stimulated by IL-1β. Methods: The levels of NO and PGE2 were measured by the Griess method and ELISA. The levels of MMP1, MMP3, and MMP13 were also measured by ELISA. Results: The results revealed that IL-1β significantly increased the production of NO, PGE2, MMP1, MMP3, and MMP13. Additionally, the increases were significantly attenuated by treatment with morin. Furthermore, IL-1β-induced NF-κB activation was suppressed by morin. In addition, the expression of Nrf2 and HO-1 were increased by morin and knockdown of Nrf2 could prevent the anti-inflammatory effects of morin. Conclusion: In conclusion, this study suggested that morin attenuated IL-1β-induced inflammation by activating the Nrf2 signaling pathway.

Glycosaminoglycans (GAGs) are among the most complex, biologically active polysaccharides in nature. The complexity of GAGs greatly impedes their synthesis, thus complicating the structure-property studies that are so necessary for us to understand the roles of GAGs in natural processes, in pathogen invasion, and to understand how to develop effective interventions, for example, to prevent undesired GAG hijacking by pathogens. Total synthesis of GAG oligomers from monosaccharide building blocks is useful, but incredibly labor-intensive, expensive, and inefficient. In this study, we report a regiospecific synthetic route to two types of designed GAG analogs by chemical modification of commercially available, inexpensive cellulose acetate. Cellulose acetate was first brominated, followed by azide displacement to introduce azides as the GAG amine precursors. The resulting 6-N cellulose acetate was then saponified to liberate 6-OH groups. Subsequent oxidation of the liberated primary hydroxyl groups to carboxyl groups was smoothly effected by a TEMPO-catalyzed process. Finally, the azides were reduced to amines using an aqueous process, new to polysaccharide chemistry, employing reduction by dithiothreitol (DTT). Alternatively, another process new to polysaccharide chemistry could be employed to convert most of the azides to acetamido groups (mimicking those present, for example, in native hyaluronic acid) by reduction with thioacetic acid. All the intermediates and products were characterized by H NMR,C NMR, and FT-IR spectroscopy. This synthetic route provides access to GAG analogs that will be of great interest for exploring structure-property relationships in various biomedical applications.

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