Understanding the interaction between a uridine derivative and Langmuir monolayers as bacterial membrane models

Studying and understanding the interaction between a compound with potential biological activity and the cell membrane is pivotal for predicting its efficacy as a pharmacological agent. On this basis, Langmuir films, ultrathin layers with the thickness of a single molecule formed at the air-water interface, serve as an invaluable tool to mimic cell membranes and their interaction with bioactive compounds. Employing the Langmuir technique, we can meticulously manipulate parameters such as surface pressure, available area for the film, subphase pH, temperature, and monolayer composition, thereby achieving superior mimicry. Thus, the focus of this study is to explore the interaction between 3,4-acetonide-uridine-succinatecholesterol (PNM3), a uridine derivative with potential biological properties, and Langmuir films comprising dipalmitoylphosphatidylethanolamine (DPPE) and dioleoylphosphatidylethanolamine (DOPE), as phospholipids found in significantly quantities in bacterial cell membranes. Various techniques, including surface-pressure isotherms, tensiometric stability tests, and Brewster angle microscopy (BAM), were employed to evaluate the effects of PNM3 on the lipid monolayers. Observations revealed alterations in the isotherms post-PNM3 introduction, indicating an interaction between the compound and the monolayer, shedding light on whether the compound was incorporated or expelled from the air-water interface. Noteworthy changes in film stability were observed after PNM3 addition. Additionally, BAM images illustrated morphological changes in the film after the drug introduction. In summary, PNM3 induced significant changes in the lipid monolayers' thermodynamic and morphological characteristics.