The interactions of phospholipid vesicles with some anti-inflammatory agents

Abstract

Differential scanning calorimetry showed that lecithin vesicles interact with the anti-inflammatory agents indomethacin, ibuprofen, and phenylbutazone. Monophenylbutazone, a physiologically inactive compound that is structurally closely related to phenylbutazone, only had a small influence on the thermal properties of the vesicle walls. Intensive intermolecular steady-state nuclear Overhauser effects (NOEs) were observed by 1D and 2D NMR methods between the hydrogen atoms of the chlorophenyl group of indomethacin and the hydrogen atoms of the alkyl chains of lecithin. Only weak interactions were found between indomethacin protons and head group protons of lecithin. NOE growth rates showed that the distance between the chlorophenyl groups of indomethacin and the alkyl chains of lecithin must be of the same order as some intramolecular distances in lecithin. It was concluded that these chlorophenyl groups are able to penetrate into the lecithin bilayer of vesicle walls.