Hemolytic Activity of a Dental Adhesive Monomer (4-Methacryloyloxyethoxycarbonylphthalic Anhydride, 4-META) and Its Interaction with Phospholipid Liposomes as Determined by NMR and DSC.

Abstract

To clarify the mechanism of interaction of dental adhesive monomers with biological membranes at the molecular level, we studied the interaction of 4-META and its related compounds (4-methacryloyloxyethoxy-carbonylphthalic acid 4-MET, phthalic acid and phthalic anhydride) with the dipalmitoylphosphatidylcholine (DPPC) liposome system, using NMR and DSC. Changes in NMR chemical-shifts and phase transition temperatures at pH 7.4 of DPPC liposomes induced by phthalic anhydride and 4-META were greater than those induced by phthalic acid. NMR spectra of the DPPC/4-META liposome system were similar to those of the DPPC/4-MET liposome system, suggesting hydrolysis of the anhydride moiety of 4-META in D₂O. The effects of 4-META and its related compounds on human erythrocytes were also studied. 4-META and phthalic anhydride showed a greater degree of hemolysis as compared to 4-MET and phthalic acid, indicating that ionized compounds do not impregnate into biological membranes.