Optimization on preparation conditions of Rehmannia glutinosa polysaccharide liposome and its immunological activity

• Reverse-phase evaporation method was chosen as the optimal method for preparation of RGPL.
• Based on single factor investigation, RSM was employed to determine the optimum preparation conditions of RGPL.
• RGPL significantly stimulated proliferation of murine splenic lymphocyte in vitro.

The aim of this study was to investigate the optimizing preparation conditions and immunological enhancement activity of Rehmannia glutinosa polysaccharide liposome (RGPL). RGPL was prepared using the reverse-phase evaporation method and optimized using the response surface methodology. The immunological enhancement activity of RGPL on splenocyte proliferation was measured. These results showed that the optimum preparation conditions were: a soybean phosphatide to cholesterol ratio of 8:1, a chloroform to methanol ratio of 3:5, a soybean phosphatide to tween 80 ratio of 10:1, a temperature (°C) of 66 °C and an entrapment efficiency of 72.753 ± 0.318%. In a single stimulation of drugs, RGPL could significantly promote splenocyte proliferation, specifically at 200 μg mL−1. Moreover, in a synergistic stimulation of drugs with LPS or PHA, a significant difference was obtained between the RGPL and RGP at 100–400 μg mL−1, which indicated that the immunological enhancement of RGP was significantly improved after encapsulation with the liposome.