Skin regeneration is a process that regenerates damaged or aged skin cells, resulting in a healthier and younger appearance. The demand for nano dosage forms containing phyto-compounds in the cosmetics industry is increasing daily to control or prevent this process. Phyto-compounds with cell regenerative properties often show limited effectiveness in conventional use due to their low hydrophilicity and molecular weight, as well as their low absorption from the skin. Glycyrrhizic acid (GA), a phyto-compound obtained from licorice root, has many pharmacological properties, including skin regeneration properties. The aim of this study is to develop a highly stable GA-containing nanoemulsion (GA-NE) formulation for topical application, determine its anti-collagenase activity, and evaluate its safety and effectiveness by in vitro cell culture methods. In this context, GA-NEs were synthesized with sixteen production procedures using independent variables (oil, water percentage, surfactant, and homogenization time). The average droplet size, polydispersity index (PdI), and zeta potential (ZP) of the synthesized GA-NEs were determined by dynamic light scattering (DLS) analysis. The heating-cooling cycle (H-C) test result showed that the F4P3 formulation was the most stable formulation. Therefore, 90-day physicochemical stability tests were performed with the F4P3 formulation. In vitro release results revealed that GA was released from NEs at a rate of 93.15 ± 0.61 % within 24 h. An ex vivo permeation and penetration study was performed, and the permeation and penetration profile of F4P3 was determined. In vitro cell culture studies showed that the F4P3 formulation had higher cell viability and regeneration than GA in the HaCaT cell line. Anti-collagenase activity results also revealed a better activity of the F4P3 formulation compared to GA. Consequently, characterization, efficacy, and safety studies showed that the F4P3 formulation could be an innovative cell regeneration product candidate suitable for topical use with high stability.
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