Optimized Solubilization of Albizia myriophylla Benth. Extract Using I-Optimal Design for Anti-Streptococcus mutans Activity.

Albizia myriophylla Benth. is a medicinal plant possessing anti-Streptococcus mutans activity, a key pathogen associated with dental caries, due to the presence of antimicrobial compounds such as lupinifolin. This study aimed to optimize a solvent system for solubilizing A. myriophylla extract. Initially, the anti-S. mutans activity of the stem extract was determined, revealing minimum inhibitory and minimum bactericidal concentrations of 8 and 256 μg/mL, respectively. Five solvents-water, 95% ethanol, glycerin, polyethylene glycol (PEG) 400, and propylene glycol (PG)-were evaluated. The extract exhibited higher solubility in PG, followed by 95% ethanol and PEG 400. Based on these results, 95% ethanol, PG, and water were selected for mixture optimization using an I-optimal design. A design space was constructed to ensure a minimum of 90% recovery of lupinifolin, achieving approximately 50% of the defined knowledge space. The optimal formulation for preparing a 5% A. myriophylla extract consisted of 95% ethanol, PG, and water in a mass ratio of 0.30:0.63:0.07. This formulation yielded a lupinifolin recovery ranging from 94.18% to 101.01%. A verification step confirmed the predictive accuracy and reliability of the model. Finally, the optimal formulation was evaluated for its anti-S. mutans activity, which demonstrated effective antimicrobial properties. In conclusion, this study successfully identified a suitable solvent system for solubilizing A. myriophylla extract, which can serve as a guideline for the development of oral sprays targeting S. mutans in future research.