Interactions Between Ibuprofen and Phospholipid Monolayers in Cell Membrane Model Systems

Ali Amer ’23

Student: Ali Amer ’23
Research Mentor: Bethany Rudd (OWU Department of Chemistry)

Everyone has taken over-the-counter (OTC) medication at some point, be it for pain relief or for reducing a fever or inflammation. However, what we don’t always know is how these drugs interact with the membranes of our cells. Our study focuses on understanding the nature of interactions between ibuprofen and a component of our cell membranes. Investigating this piece of the puzzle helps us to understand how ibuprofen and other medications work in our bodies.

The interactions between the lipid components of a cell membrane and amphiphilic drugs are directly related to the efficacy of the drug itself and how it works. This study focuses on the interactions between ibuprofen, a common over-the-counter medication, and a model phospholipid monolayer system, dipalmitoylphosphatidylcholine (DPPC). Surface pressure-area isotherms were recorded through the compression of the DPPC monolayer in a Langmuir trough with and without ibuprofen. Previous studies in the literature put forward a controversy centered around the method of introduction of ibuprofen into the model system (introduction via the aqueous subphase versus co-spreading with the DPPC monolayer) and how the drug interacts with the Langmuir monolayer in these two scenarios. In this work, significant effects were observed in surface pressure-area isotherms upon subphase introduction of ibuprofen whereas no observable change was observed with co-spreading. Further analysis of the isotherms was carried out through the calculation of the compressibility modulus to determine the fluidizing effect of ibuprofen on the DPPC monolayer. The disappearance of phase transitions between the gas, liquid expanded and liquid condensed regions of the isotherm was found to be more pronounced as the concentration of ibuprofen was increased in the subphase. The compressibility modulus values indicated that at high ibuprofen concentrations (50 µM), the monolayer became more fluid. This work represents the beginning stages of our study of ibuprofen with DPPC model membrane systems. Future work will focus on identifying the moieties involved in these interactions as well as increasing the complexity of our model system to better mimic human body conditions.