Tryptanthrin, a constituent of <i>Persicaria tinctoria</i> , suppresses osteoclastogenesis and enhances the expression of tight junction proteins and cell adhesion molecules in gingival epithelial cells

Tryptanthrin, an ingredient of Persicaria tinctoria, has been reported to exhibit antioxidant and anti-inflammatory effects. To elucidate the potential role of tryptanthrin in periodontal disease, we investigated its effects on bone metabolism and innate immunity, including the epithelial barrier. RAW264.7 cells were cultured with soluble receptor activator of nuclear factor-κB ligand (sRANKL) and tryptanthrin, and stained with Tartrate-Resistant Acid Phosphatase (TRAP) to evaluate osteoclastgenesis. The expression of osteoclast differentiation markers was examined using western blot analysis. OBA-9 cells were cultured with tryptanthrin, and the expression of tight junction (TJ) proteins and cell adhesion molecules (CAMs) was examined by western blot analysis. We found that tryptanthrin significantly inhibited osteoclastgenesis and suppressed the expression of osteoclast differentiation markers. Further, tryptanthrin enhanced the expression of TJ proteins and CAMs. These results indicated that tryptanthrin inhibits osteoclastgenesis by downregulating the osteoclast differentiation markers and enhances cell-cell adhesion by upregulating TJ proteins and CAMs.