1-palmitoyl-2-oleoylphosphatidylcholine and lauryl-gallate

The effect of different amounts of lauryl gallate (LG) on properties of the model membranes of phosphatidylcholines (PC), differing in the presence of double bonds in the hydrocarbon chains, and phosphatidylglycerol (PG) was described in terms of phase behaviour of mixtures, interactions between both components, monolayers stability and their organization. The Langmuir monolayer technique was used to monitor the surface thermodynamics (i.e. the excess area and excess Gibbs energy of mixing) on the basis of surface pressure-area per molecule (π-A) isotherms. Simultaneously, morphology of the studied monolayers was visualized by the Brewster angle microscopy (BAM). This allowed evaluating the kind and magnitude of interactions which influence on the phase behaviour and structural properties of the monolayers. The obtained results can be helpful to reveal the mechanism of phospholipid antioxidant protection and important pharmacological (antimicrobial) role of lauryl gallate for production of effective therapeutic substances.

Topics: 1,2-Dipalmitoylphosphatidylcholine; Gallic Acid; Membrane Lipids; Microscopy, Polarization; Phosphatidylcholines; Phospholipids; Surface-Active Agents

To characterize surfaces of phospholipid/lauryl gallate monolayers deposited on mica there were applied numerous methods such as measurements of advancing and receding contact angles and optical profilometry, as well as atomic force microscopy. As a result, there was no found correlation between contact angles (and their hysteresis) or surface roughness. Hence, most monolayer topographical changes at the Ångstrom level accompanied changes in surface chemistry which resulted in the hysteresis of contact angle on thin films. The obtained results indicate that stability and permeability of the binary films are determined by the composition and stoichiometry of the mixed monolayers. These results can be helpful for insight into lauryl gallate behavior in living systems, i.e., in membrane antioxidant protection and pharmacological activities.

Topics: 1,2-Dipalmitoylphosphatidylcholine; Aluminum Silicates; Gallic Acid; Microscopy, Atomic Force; Phosphatidylcholines; Phospholipids; Surface Properties; Wettability