Optimization of puerarin nanoemulsion based on glycyrrhizic acid by central composite design-response surface method and its in vitro release studies / 中草药

ABSTRACT

Objective: Puerarin nanoemulsion (Pue-NE) was prepared with glycyrrhizic acid as a natural stabilizer, and its release characteristics in vitro were investigated. Methods: Data processing was performed using particle size and polydispersity index (PDI) as independent variables, and using the overall desirability (OD) as the evaluation index. The central composite design-response surface method was used to optimize the prescription, and the physical and chemical properties and release characteristics of Pue-NE prepared by the optimal prescription were investigated. Results: The best prescription for Pue-NE is puerarin at a concentration of 5.0 mg/mL, glycyrrhizic acid at a concentration of 1.75 mg/mL, and caprylic glyceride in an amount of 3.5 mL. The average particle size of the nanoemulsion is (184.5 ± 0.8) nm, the PDI is 0.088 ± 0.002, the zeta potential is (10.56 ± 0.35) mv, the conductivity is (98.3 ± 0.4) μs/cm, pH is 6.750 ± 0.005, solubility (4.970 ± 0.008) mg/mL, drug loading is (99.4 ± 0.2)%, turbidity (24.3 ± 1.0) cm-1 (n = 3). It was identified as O/W emulsion by dyeing method. TEM scanning results show that the droplets are spherical and uniform in size and the stability results showed that Pue-NE has good storage stability at 25 ℃. In vitro release results showed that Pue-NE has the greatest release in phosphate buffered pH 6.8 within 24 hours. Conclusion: The preparation of Pue-NE with glycyrrhizic acid as a natural stabilizer is not only simple and convenient, but also can effectively replace the use of traditional chemical synthetic stabilizers and improve the solubility of puerarin.