Cinnamophilin isolated from Cinnamomum philippinense protects against collagen degradation in human chondrocytes.

To investigate the therapeutic potential of naturally occurring cinnamophilin against cartilage degradation and its action mechanisms, its effects on matrix metalloproteinase (MMP)-1 and -13 induction were examined in the human SW1353 chondrocytic cell line. Human chondrocytes (SW1353) were stimulated with interleukin (IL)-1β, and then mitogen-activated protein kinase (MAPK) and c-Jun activations, inhibitory κB-α (IκB-α) degradation, and MMP-1, and 13 expressions were assayed by a Western blot analysis. Cinnamophilin strongly inhibited MMP-1 and -13 induction in IL-1β-treated (30 ng/mL) SW1353 cells in a concentration-dependent manner, and it also reduced MAPK family members including extracellular signal-regulated kinase (ERK), p38 MAPKs, and c-Jun N-terminal kinase. Moreover, nuclear factor (NF)-κB signaling activation through IκB-α degradation, IκB kinase (IKK)-α/β, and p-65 phosphorylation was restored by cinnamophilin upon IL-1β stimulation. Importantly, results showed that IL-1β-induced activation of phosphorylated (p)-c-Jun in chondrocytes was significantly inhibited by cinnamophilin. These results indicate that cinnamophilin inhibited MMP-1 and -13 expressions in IL-1β-treated chondrocytes through either NF-κB or ERK/p38 MAPK downregulation and/or suppressing p-c-Jun pathways. Furthermore, these findings suggest that cinnamophilin may have the potential for chondroprotection against collagen matrix breakdown in cartilage of diseased tissues such as those found in arthritic disorders.