The alteration of lipid bilayer dynamics by phloretin and 6-ketocholestanol

• We studied the effect of phloretin and 6-ketacholestanol on osmotically induced water flow and water interfacial structure.
• Water organization was measured with solvent relaxation method and water flux across membrane with stopped-flow method.
• We showed that dipole potential changes do not correlate with interfacial water hydration and micro-viscosity.
• Our data revealed correlation between dipole potential and probability of spontaneous lipid pore formation values.
• No such correlation for water flux, following lipid pore formation, was observed.

Lipid bilayer properties are quantified with a variety of arbitrary selected parameters such as molecular packing and dynamics, electrostatic potentials or permeability. In the paper we determined the effect of phloretin and 6-ketocholestanol (dipole potential modifying agents) on the membrane hydration and efficiency of the trans-membrane water flow. The dynamics of water molecules within the lipid bilayer interface was evaluated using solvent relaxation method, whereas the osmotically induced trans-membrane water flux was estimated with the stopped-flow method using the liposome shrinkage kinetics. The presence of phloretin or 6-ketocholestanol resulted in a change of both, the interfacial hydration level and osmotically driven water fluxes. Specifically, the presence of 6-ketocholestanol reduced the amount and mobility of water in the membrane interface. It also slows the osmotically induced water flow. The interfacial hydration change caused by phloretin was much smaller and the effect on osmotically induced water flow was opposite to that of 6-ketocholestanol.