title: Effect of divalent cations on the membrane properties of the lipid A analog E5531.
abstract: To obtain information on the effects of Mg2+ on the membrane properties of the lipid A analog E5531, we determined the size, structure, zeta potential, membrane fluidity, and micropolarity of the aggregates and the permeability of the E5531 membrane after the addition of Mg2+. E5531 forms a vesicle structure and within the molar ratio of [E5531]:[Mg2+] = 1:3, Mg2+ increased the zeta potential of the E5531 membrane, but did not change the size of the aggregates (approximately 20 nm). Within that molar ratio, Mg2+ decreased the membrane fluidity and micropolarity of E5531 and increased the phase transition temperature. Above the molar ratio of [E5531]:[Mg2+] = 1:5, the size of the aggregates was increased, but at [E5531]:[Mg2+] = 1:3, the size of the aggregates was similar to that in the absence of Mg2+ (approximately 20 nm), and we could stabilize the aggregates in rat plasma.
authors.affiliation: Formulation Research Laboratory, Kawashima, Eisai Company, Limited, Gifu, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Asai
authors.forename: S
authors.initials: S
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D002413:Cations, Divalent / Q000737:chemistry; D003619:Dansyl Compounds / Q000737:chemistry; D004355:Drug Stability; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008050:Lipid A / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry; D008274:Magnesium / Q000737:chemistry*; D008560:Membrane Fluidity / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D008567:Membranes, Artificial; D010316:Particle Size; D051381:Rats
chemical_list: D002413:Cations, Divalent; D003619:Dansyl Compounds; D005456:Fluorescent Dyes; D008050:Lipid A; D008567:Membranes, Artificial; C092845:E 5531; D008274:Magnesium