Increased cutaneous wound healing effect of biodegradable liposomes containing madecassoside: preparation optimization, in vitro dermal permeation, and in vivo bioevaluation

Abstract

Madecassoside (MA) is highly potent in treating skin disorders such as wounds and psoriasis. However, the topical wound healing effect of MA was hampered by its poor membrane permeability. In order to overcome this shortcoming, MA liposomes were designed and prepared by a double-emulsion method to enhance transdermal and wound healing effects. In this study, response surface methodology was adopted to yield the optimal preparation conditions of MA double-emulsion liposomes with average particle size of 151 nm and encapsulation efficiency of 70.14%. Moreover, MA double-emulsion liposomes demonstrated superior stability and homogeneous appearance in 5 months; their leakage rate was <12% even at 37°C and <5% at 4°C within 1 month. In vitro skin permeation, skin distribution, and burn wound healing of MA liposomal formulations were conducted for the first time to evaluate MA delivery efficiency and wound healing effect. The transdermal property and wound cure effect of MA double-emulsion liposomes were superior to those of MA film dispersion liposomes, and both the methods were endowed with an excellent performance by polyethylene glycol modification. In conclusion, double-emulsion liposome formulation was an applicable and promising pharmaceutical preparation for enhancing MA delivery toward wound healing effect and improving wound-healing progress.

Keywords: double-emulsion method; madecassoside liposomes; skin permeation; transdermal property; wound-healing effect.

Figure 1

The structure of madecassoside and the schematic for madecassoside-contained liposomes penetrating through the skin and fusing with the cell membrane.

Figure 2

Response surface graphical analysis. Notes: (A) Effect of the ratio of egg yolk lecithin to cholesterol (X₁) and concentration of madecassoside (X₂) on drug loading efficiency. (B) Effect of the ratio of egg yolk lecithin to cholesterol (X₁) and the stirring speed (X₃) on drug loading efficiency. (C) Effect of concentration of madecassoside (X₂) and the stirring speed (X₃) on drug loading efficiency.

Figure 3

Morphological characterization of liposomes. Notes: Size distribution (A) of madecassoside double-emulsion liposomes (a) and neat liposomes (b), and SEM of madecassoside double-emulsion liposomes (B) and neat liposomes (C). Abbreviations: SEM, scanning electron microscopy; Mag, magnification; WD, work distance; EHT, extra high tension.

Figure 4

The physical stability of madecassoside liposomes stored at 4°C for 5 months. Notes: Product appearance and fluorescent-inverted morphology of madecassoside double-emulsion liposomes (400×) (A), madecassoside film dispersion liposomes (400×) (B), and madecassoside ethanol-injection liposomes (100×) (C).

Figure 5

Leakage rates of MA liposomes. Notes: Leakage rates of madecassoside film dispersion liposomes in 10 hours (A) madecassoside double-emulsion liposomes in 1 month at different temperatures (B). Abbreviation: MA, madecassoside.

Figure 6

In vitro permeation of madecassoside liposomes. Notes: In vitro permeation of madecassoside liposomes in 48 hours (A). Isolated skin appearances changed at different times in 24 hours (B). In vitro permeation of madecassoside liposomes with changed skin every 4 hours in 12 hours (C). Abbreviation: MA, madecassoside.

Figure 7

Madecassoside delivered by liposomal formulations and skin localization. Abbreviation: MA, madecassoside.

Figure 8

Evaluation of wound healing effect. Notes: Macroscopic appearances of skin wounds treated with normal saline as control, madecassoside solution, liposome formulations at different day stage (A). Efficacy index evaluation of different treatments on wound size reduction (B). Data are expressed as mean ± SD. ^*P<0.05, ^**P<0.01 vs NS control. ⁺P<0.05, ⁺⁺P<0.01 vs MA solution. Abbreviations: MA, madecassoside; NS, normal saline.