J. Biol. Chem., Vol. 261, Issue 22, 10196-10203, Aug, 1986
A scanning calorimetric study of the interaction of anthracyclines with neutral and acidic phospholipids alone and in binary mixtures
PP Constantinides, N Inouchi, TR Tritton, AC Sartorelli and JM Sturtevant
High sensitivity differential scanning calorimetry was employed to study
the thermotropic behavior of multilamellar vesicles of neutral and acidic
phospholipids and binary mixtures thereof in the presence of anthracycline
antibiotics. Adriamycin and its lipophilic analogue, N-
trifluoroacetyladriamycin-14-valerate (AD32) were investigated and compared
to chlorpromazine and quinidine with respect to their ability to affect the
pretransition and the main transition of the phospholipids suspended in
physiological buffer. With liposomes of neutral
dipalmitoylphosphatidylcholine the observed effects paralleled to some
extent the corresponding octanol/buffer partition coefficients, with
adriamycin being the least effective. Calorimetric measurements on
liposomes prepared from pure dipalmitoylphosphatidylglycerol or from binary
mixtures of dipalmitoylphosphatidylglycerol and
dipalmitoylphosphatidylcholine showed that modulation of bilayer properties
by adriamycin was greatly enhanced in the presence of negatively charged
lipid headgroups presumably as a result of electrostatic interactions. AD32
interacted differently from adriamycin with the acidic bilayers at low drug
concentrations, in a manner similar to that of its interaction with neutral
bilayers. At high drug concentrations both adriamycin and AD32 produced
transitions with multiple peaks not exhibited by chlorpromazine and
quinidine which may be the result of a specific association of the
anthracyclines with dipalmitoylphosphatidylglycerol. All four drugs
produced only minor changes in the enthalpy of the main transition of the
investigated lipids. The present findings are discussed in terms of their
possible physiological relevance.