A study of the release of active peptide from semisolid hydrogels measured with Franz diffusion apparatus

Introduction
Recently there has been a growth of interest in novel skin care formulations containing active ingredients, such as low molecular weight peptides. In this paper we present new skincare formulations of hydrogels containing a tetrapeptide (N-Pro-Val-Ala-Gly). Low molecular peptides evolved from research into wound healing and studies on growth stimulation of human skin fibroblasts. The main aim of our study was to perform tests of release of the peptide through synthetic membrane and assessment of the rate of release of peptide from hydrogels from different recipes.

Material and methods
The peptide was identified (ion mass, productivity, homogeneity) and the formulations were characterized in terms of physicochemical parameters. Permeation studies were conducted using Franz diffusion cells. The collected samples were subjected to determination by the MALDI-TOF-MS method and the analytical HPLC technique. The ex vivo tests allow for testing of active substances outside a living organism while representing the effects of these compounds on the organism.

Results
The results showed that the properties of the formulations strongly determined the release rate of the tetrapeptide. Furthermore, lemon essential oil modified the penetration of the peptide through membranes which we used.

Conclusions
The presence of the lemon essential oil in the formulations reduced the time of penetration of the lipophilic peptide.