Fluphenazine: From an isolated molecule to its interaction with lipid bilayers

Spectroscopic Properties and Biological Activity of Fluphenazine Conjugates with Gold Nanoparticles

Fluphenazine (FPZ) is a well-known neuroleptic that has attracted considerable scientific interest due to its biocidal, virucidal, and antitumor properties. Although methods for encapsulating and delivering FPZ to enhance its activity and reduce side effects have been developed, there is still limited knowledge about its conjugates with gold nanoparticles (AuNPs). Therefore, the aim of this research was to develop a preparation method for stable FPZ-AuNP conjugates and to investigate their physicochemical and biological properties. FPZ-AuNP conjugates were synthesized via a ligand exchange process on the surface of gold nanoparticles (AuNPs) with an average size of 17 ± 5 nm. Electrokinetic measurements revealed that the zeta potential of FPZ-AuNPs is affected by both their composition and pH. The FPZ-AuNPs exhibited an isoelectric point due to the acid-base properties of FPZ. Surface-enhanced Raman spectroscopy (SERS), combined with density functional theory (DFT), was used to determine the adsorption structure of FPZ after conjugation. Studies with human neuroblastoma cells (SH-SY5Y) revealed that FPZ-AuNP conjugates more effectively reduced cell viability compared to citrate-stabilized AuNPs alone or free FPZ molecules. The reduction in SH-SY5Y cell viability was found to be dependent on the FPZ-AuNP concentration.

Modulators of cellular cholesterol homeostasis as antiproliferative and model membranes perturbing agents

Cholesterol is an important component of mammalian cell membranes affecting their fluidity and permeability. Together with sphingomyelin, cholesterol forms microdomains, called lipid rafts. They play important role in signal transduction forming platforms for interaction of signal proteins. Altered levels of cholesterol are known to be strongly associated with the development of various pathologies (e.g., cancer, atherosclerosis and cardiovascular diseases). In the present work, the group of compounds that share the property of affecting cellular homeostasis of cholesterol was studied. It contained antipsychotic and antidepressant drugs, as well as the inhibitors of cholesterol biosynthesis, simvastatin, betulin, and its derivatives. All compounds were demonstrated to be cytotoxic to colon cancer cells but not to non-cancerous cells. Moreover, the most active compounds decreased the level of free cellular cholesterol. The interaction of drugs with raft-mimicking model membranes was visualized. All compounds reduced the size of lipid domains, however, only some affected their number and shape. Membrane interactions of betulin and its novel derivatives were characterized in detail. Molecular modeling indicated that high dipole moment and significant lipophilicity were characteristic for the most potent antiproliferative agents. The importance of membrane interactions of cholesterol homeostasis-affecting compounds, especially betulin derivatives, for their anticancer potency was suggested.

Vibrational spectroscopy combined with molecular dynamics simulations as a tool for studying behavior of reactive aldehydes inserted in phospholipid bilayers

Vibrational Fourier-transform infrared (FTIR) spectroscopy aided with molecular dynamics (MD) simulations is used for studying the interaction of several reactive aldehydes (RAs), nonanal (NA), 2-nonenal (NE), 4-hydroxy-2-nonenal (HNE) and 4-oxo-2-nonenal (ONE), with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer. The results obtained by the combination of these two techniques, supported also by electron paramagnetic resonance (EPR) spectroscopy, show that NA has the strongest stabilization in the bilayer, followed by less stabilized NE, HNE and ONE. We also revealed that HNE readily makes hydrogen bonds to carbonyl groups of POPC (but not to phosphate groups), in contrast to other RAs which are hydrogen bond acceptors and do not make hydrogen bonds with lipids. A combination of FTIR spectroscopy and MD simulations is sensitive to small chemical changes in the structures of RAs, thus making it a valuable tool for studying the weak interactions between compounds inserted to phospholipid bilayers.