Influence of chloroform in liquid-ordered and liquid-disordered phases in lipid membranes.

Molecular dynamics simulations are used to study the influence of chloroform in two different lipid membranes: one representative of a liquid-disordered phase and another one mixed with cholesterol and representative of a liquid-ordered phase. When chloroform is added to the cholesterol-containing membrane, a strong chain disordering is induced. In both cases, chloroform laterally disorganizes the membranes. The analysis of the main structural and dynamical membrane properties reveals that the interaction with cholesterol is the main factor to explain the strong disordering effect of chloroform in liquid-ordered phases. The results support and provide a molecular explanation to the observations of Regen et al. ( J. Am. Chem. Soc. 2009 , 131 , 5068 ) that suggest that chloroform loosens cholesterol-containing bilayers, thus changing their lateral lipid organization. This lipid-mediated mechanism is conjectured by Regen et al. to be responsible for the anesthetic effect of chloroform and other small volatile anesthetic compounds. This proposal is also discussed.