Effect of Purpurin-Loaded Thermosensitive Hydrogel in Periodontitis

Objectives: Periodontitis is primarily treated through the physical removal of plaque and calculus, often combined with antibiotic therapy. However, the use of antibiotics may cause systemic side effects. To address these challenges, natural compounds have been explored as potential therapeutic agents for periodontitis. This study aimed to develop a thermosensitive hydrogel containing purpurin, a natural compound, and to evaluate physical characteristics and inhibitory effects on periodontitis.
Methods: The cytotoxicity of purpurin in raw 264.7 cells and human gingival fibroblasts (HGF-1) was evaluated using the CCK-8 assay. The antibacterial activity against Porphyromonas gingivalis (P. gingivalis) was assessed using the minimal inhibitory concentration (MIC) test. To investigate the anti-inflammatory effects, inflammatory markers were evaluated using RT-qPCR in raw 264.7 cells. Thermosensitive hydrogels were formulated using poloxamer 188, pluronic F-127, and carboxymethyl cellulose sodium salt, with purpurin added varying concentrations. Gelation temperature, adhesiveness, viscosity, and purpurin release were evaluated. The biological effects of the gels were examined for cytotoxicity (CCK-8) and antibacterial activity (agar diffusion test).
Results: Purpurin showed no cytotoxicity up to 10 μM in raw 264.7 cells and up to 50 μM in HGF-1 cells (p>0.05). The MIC for P. gingivalis was 20 μM. In raw 264.7 cells, purpurin treatment significantly reduced IL-1β and IL-6 levels (p<0.05). The hydrogel gelation temperatures was between 33–35°C, with sharp viscosity increases upon gelation. It demonstrated adhesiveness supporting 15.8 g and sustained purpurin release for three days. Hydrogel extracts showed no cytotoxicity at a 25% dilution. Antibacterial activity was concentration-dependent, with purpurin-loaded hydrogels exhibiting significant efficacy (p<0.05).
Conclusions: The purpurin-loaded thermosensitive hydrogel demonstrated appropriate physical properties for intraoral application and exhibited antibacterial activity against P. gingivalis. These findings suggest that purpurin-loaded thermosensitive hydrogels could serve as a potential therapeutic agent for periodontitis treatment.