Flavonoid gossypetin protects alveolar bone and limits inflammation in ligature-induced periodontitis in mice

Background: Bacterial-induced inflammation instigates the destruction of hard and soft tissues surrounding teeth in periodontitis. In severe cases, the increased number and activity of osteoclasts induces the resorption of alveolar bones, ultimately leading to tooth loss. Because of their diverse chemical structures and bioactivities, natural compounds are often suggested to treat a wide variety of diseases, including inflammatory disorders. Methods: In the present study, we demonstrated an inhibitory effect of gossypetin, a hexahydroxy flavone, on osteoclast differentiation and bone resorption using in vitro culture of osteoclasts from mouse bone marrow macrophage (BMM) precursors and in vivo model of ligature-induced periodontitis in mice. Results: Gossypetin significantly reduced the differentiation of osteoclasts from mouse BMM precursors in the presence of the receptor activator of nuclear factor κB ligand (RANKL). In vitro, gossypetin inhibited critical signaling events downstream of RANKL including the auto-amplification of nuclear factor of activated T-cells, cytoplasmic 1, Ca²⁺ oscillations, and the generation of reactive oxygen species. In a mouse ligature-induced periodontitis model, the administration of gossypetin significantly reduced osteoclastogenesis and alveolar bone resorption. Furthermore, gossypetin prevented the ligature-induced increase in macrophages and T cells and reduced the production of tumor necrosis factor-α and interleukin-6. Conclusion: Taken together, these results show anti-osteoclastogenic and anti-inflammatory effects of gossypetin, suggesting the potential use of this natural compound in periodontitis.