Phenothiazine compounds are known as effective inhibitors of a multidrug resistance (MDR) of
tumor cells to chemotherapeutic agents. This group consists of many important substances used in human medicine such as
antipsychotic drugs in the case of
fluphenazine (FPh) or
chlorpromazine (CPZ).
Fluphenazine was on the World Health Organization (WHO) list of Essential Medicines of 2009, and its new
pyrimidine analog (FPh-prm) presented in this work has been documented to have a high anti-MDR activity. In order to discover the character of alterations of the
lipid bilayer structure caused by the presence of FPh-prm inside the
lipid membrane, which is responsible for the essential increase of an anti-MDR activity of FPh-prm, microcalorimetric (differential scanning calorimetry),
Laurdan fluorescence, (31)P nuclear magnetic resonance spectroscopy (NMR), and attenuated total reflectance Fourier transfer infrared spectroscopy (FTIR-ATR) were used for dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)
liposomes mixed with a different concentration of
amine analogue. It was stated that the formation of domains with different content of FPh-prm/DPPC can be a reason for the membrane-related mechanism of
chemoprevention associated with the inhibition of the outward transport of anticancer drugs by the
glycoprotein P (Pgp) in
cancer cells by the
pyrimidine analog of FPh. To our best knowledge, this report is the first to show the bilayer structure of domains formed by incomplete miscibility of
fluphenazine-related compounds and
phospholipid molecules. Our results provide a sound basis for the design of future modifications of anti-MDR drugs by providing very effective inhibitors of the pump activity of Pgp.