Optimization of toothtablets incorporating Albizia myriophylla Benth. stem extract obtained by eco-friendly microwave-assisted extraction

Abstract

Albizia myriophylla Benth. stems are composed of the bioactive compound lupinifolin, which has exhibited anti-Streptococcus mutans activity. Extracting this plant for incorporation into oral healthcare products is challenging. This study aimed to optimize the eco-friendly microwave-assisted extraction of A. myriophylla stems. It also optimized toothtablets incorporating A. myriophylla stem extract. First, lupinifolin was isolated, and its structure was determined for use as a biomarker in this study. Next, three extraction parameters—the solvent-to-solid ratio, microwave power, and microwave time—were screened using a one-factor-at-a-time approach before being optimized using a Box–Behnken design. The results showed that the optimized conditions that maximized the extraction yield and lupinifolin content were a solvent-to-solid ratio of 23:1, microwave power of 800 W, and microwave time of 70 s. This extract contained 16.27 ± 0.43 % lupinifolin. The extract exhibited a minimum inhibitory concentration of 32 μg/mL and a minimum bactericidal concentration of 256 μg/mL. The half-maximal inhibitory concentration with human gingival fibroblast cells was 102.70 ± 1.02 μg/mL for the extract and 76.75 ± 1.03 μg/mL for lupinifolin. The extract was solidified using microcrystalline cellulose and colloidal silicon dioxide before being incorporated into the toothtablet formulation. Three factors in toothtablet production—compression force, microcrystalline cellulose content, and hydrated silica content—were also screened using a one-factor-at-a-time approach before being optimized using a Box–Behnken design. The results showed that the optimized conditions that approached the desired properties were a compression force of 2500 psi, microcrystalline cellulose content of 12 %, and hydrated silica content of 10 %. The developed toothtablets contained 35.64 ± 0.45 mg of lupinifolin per 650 mg toothtablet (or approximately 5.5 % lupinifolin per toothtablet) and retained their anti-S. mutans activity. They appeared safe for human gingival fibroblasts, even when treated for 2 min, with a maximum concentration of 2000 μg/mL. In conclusion, the developed toothtablets incorporating A. myriophylla stem extract can potentially serve as a high-quality, antibacterial, and safe alternative to traditional toothpaste.