Mechanistic Aspects of Membrane Destruction of Dipalmitoylphosphatidylcholine Liposomes by Alkyltrimethylammonium Bromides

Abstract

The membrane permeability of carboxyfluorescein (CF) trapped dipalmitoylphosphatidylcholine liposomes was facilitated by the presence of long-chain alkyltrimethylammonium bromides (ATAB) and characteristic dependency of this parameter on concentration and alkyl-chain length was noted. Octyl- and decyltri-methylammonium bromides had little or no effect for CF release, while this release was augmented by dodecyl- and tetradecyltrimethylammonium in proportion to concentrations. For longer chain cetyl- and stearyltrimethylammonium bromides exhibiting an abnormal activity-concentration relationship, CF release was remarkably stimulated at significantly low concentrations, while virtually not at all at high concentrations. Based on the data from light-scattering study and differential scanning calorimetry, a CF-releasing mechanism is proposed. The preparation and destruction of liposomes containing anti-inflammatory drugs glycyrrhizinic acid and methylglycyrrhizinate as membrane components were also examined.