Cinnamon subcritical water extract attenuates intestinal inflammation and enhances intestinal tight junction in a Caco-2 and RAW264.7 co-culture model

Cinnamon is known to have several physiological effects; the effects of Cinnamomum japonicum Sieb. on anti-inflammation and tight junctions were investigated in the cellular intestinal inflammation model. Cinnamon subcritical water extract (CSWE) significantly down-regulated the protein and expression levels of nitrite, prostaglandin E2 (PGE₂), interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α, nuclear factor kappa B (NF-κB) activity, and the phosphorylation of the factors of the NF-κB pathway. It also significantly decreased the permeability but increased the transepithelial electrical resistance (TEER) value and the protein and expression levels of tight junction proteins (i.e., zonula occludens (ZO)-1, occludin, and claudin-1). Furthermore, cinnamic acid and cinnamaldehyde, the major components of C. japonicum, inhibited the phosphorylation of the NF-κB pathway and increased the tight junction protein expression. CSWE from C. japonicum may improve intestinal health by enhancing tight junctions and inhibiting inflammation of the intestines.