Preparation and characterization of glycyrrhetinic‐acid loaded PEG‐modified liposome based on PEG‐7 glyceryl cocoate

The aim of the study was to develop a kind of glycyrrhetinic acid (GA) liposome modified by PEG‐7 glyceryl cocoate for cosmetic use. Encapsulation efficiency, particle morphology, particle size, zeta potential, and Fourier transform infrared spectroscopy (FTIR) were studied to get its physico‐chemical properties. Release property, skin permeation in vitro, and storage stability were also investigated to evaluate the application performance. The results showed that the PEG‐modified liposomes were spherical particles with mean particle size of 117 ± 4.6 nm. Zeta potential and average encapsulation efficiency were −22.5 ± 0.54 mv and 91.9 ± 2.43%, respectively. The FTIR results indicated that GA had been loaded successfully into the liposomes. Compared with the non‐PEG‐modified liposomes, the PEG‐modified GA liposomes showed lower release rate and higher deposition in epidermis/dermis in vitro study, and also possessed better stability according to the little change of particle size during 30 days. Practical applications: Liposomes are widely used in drug delivery system but rarely used in cosmetics. It is necessary to develop a kind of liposome especially for cosmetic use. Different from other non‐modified liposomes, all of the materials used in this study are non‐toxic which guarantee the safety. The high liposome concentration up to 10% w/w also makes it efficient in large‐scale production. Furthermore, the cooperation of PEG‐7 glyceryl cocoate could prolong the release rate of GA from liposomes, and thus, achieve a better application performance. These results indicate that PEG‐modified liposomes can be a potential delivery system for the water‐insoluble GA and be used in cosmetics. The forming mechanism of the GA modified liposome in this chart was as follows: the water insoluble GA dissolved in the PEG‐7 glyceryl cocoate and the organic phase of phospholipids was put into the water phase at the same time, the phospholipid molecules wrapped the GA in the bilayers and the PEG‐7 glyceryl cocoate was bonded to the hydrophilic group of liposome vesicles. This structure made the liposome more smaller and higher encapsulation efficiency, and it also brought a prolonged release rate and better drug deposition in epidermis compare with the non‐modified ones.