The Influence of the Amphiphilic Properties of Peptides on the Phosphatidylinositol Monolayer in the Presence of Ascorbic Acid

<i>Acne vulgaris</i> is one of the most common dermatological diseases and is strongly connected with the pathological growth of the <i>Cutibacterium acnes</i>. More than half of the cultures of this bacterium are resistant to antibiotics, resulting in the proposal of the use of antibacterial peptides as an alternative to traditional antibiotics. Ascorbic acid (AA) and its antioxidant properties may ally in acne therapy. The aim of this study was to determine the influence of the selected antibacterial peptides in the presence of ascorbic acid and 3-O-ethyl-ascorbic acid (EAA) on the properties of the monolayer formed by phosphatidylinositol. Studies of the properties of the phosphatidylinositol monolayer were carried out using the Langmuir-Wilhelmy balance. The recorded compression isotherms, hysteresis loops, and surface pressure values recorded at specific time intervals were evaluated to assess the influence of ascorbic acid and its derivatives in the presence of antimicrobial peptides on the stability and organization of phosphatidylinositol monolayers. The addition of AA to the subphase caused a faster phase transition at over 60 Ų/molecule and significantly reduced the plateau surface pressure by about 20% in most of the systems tested. The studied monolayers were found to be in the expanded liquid state (40.23-49.95 [mN/m]) or in the transition between the expanded and condensed liquid phase (51.47-60.98 [mN/m]). Compression and decompression isotherms indicated the highest flexibility of the systems at 20 °C and 25 °C. The surface pressure versus time dependence indicated the stability of the phosphatidylinositol monolayer with 3-O-ethyl-ascorbic acid and antimicrobial peptides up to 35 °C.