Effects of sodium β-sitosteryl sulfate on the phase behavior of dipalmitoylphosphatidylcholine

Abstract We have studied the phase behavior of dipalmitoylphosphatidylcholine (DPPC) containing sodium β -sitosteryl sulfate (PSO 4 ). PSO 4 was found to lower the phase transition temperature of DPPC to a higher degree than cholesterol or β -sitosterol. It also gave rise to the formation of a modulated (ripple) phase ( P β ) at low to moderate concentrations. At concentrations greater than 25 mol%, it completely changed the membrane into a fluid phase. This shows that PSO 4 is capable of disordering the hydrocarbon chains of PC efficiently. The characteristics of PSO 4 for fluidizing the membrane can be useful for the pharmaceutical and cosmetics industries.