Interaction of the Macrolide Antibiotic Azithromycin with Lipid Bilayers: Effect on Membrane Organization, Fluidity, and Permeability

Abstract

Purpose. To investigate the effect of a macrolide antibiotic, azithromycin, on the molecular organization of DPPC:DOPC, DPPE:DOPC, SM:DOPC, and SM:Chol:DOPC lipid vesicles as well as the effect of azithromycin on membrane fluidity and permeability. Methods. The molecular organization of model membranes was characterized by atomic force microscopy (AFM), and the amount of azithromycin bound to lipid membranes was determined by equilibrium dialysis. The membrane fluidity and permeability were analyzed using fluorescence polarization studies and release of calcein-entrapped liposomes, respectively. Results. In situ AFM images revealed that azithromycin leads to the erosion and disappearance of DPPC and DPPE gel domains, whereas no effect was noted on SM and SM:cholesterol domains. Although azithromycin did not alter the permeability of DPPC:DOPC, DPPE:DOPC, SM:DOPC, and SM:Chol:DOPC lipid vesicles, it increased the fluidity at the hydrophilic/hydrophobic interface in DPPC:DOPC and DPPE:DOPC models. This effect may be responsible for the ability of azithromycin to erode the DPPC and DPPE gel domains, as observed by AFM. Conclusions. This study shows the interest of both AFM and biophysical methods to characterize the drug-membrane interactions.

Characterisation of chlorpromazine binding to lipid bilayer membranes

“…Previously referred to as the 'first process' in relation to SPR data, we believe the observed affect was attributable to the electrostatic and hydrophobic interactions of CPZ in the lipid bilayer [19]. As a result, the drug potentially disrupts the interactions between the lipid polar headgroups and interfacial domains, affecting the T M of the lipid bilayer as the phospholipids became further disordered and possess more motional freedom [19,20]. In comparison to SPR data, the effect of CPZ on the T M of DMPC was observed at a much lower concentration, however, it also important to once again establish that the interaction observed using SPR was during a much shorter time period, typically 2 minutes.…”

“…Interestingly, a defect in the bilayer was also observed throughout the course of imaging. Previously referred to as the 'first process' in relation to SPR data, we believe the observed affect was attributable to the electrostatic and hydrophobic interactions of CPZ in the lipid bilayer [19]. As a result, the drug potentially disrupts the interactions between the lipid polar headgroups and interfacial domains, affecting the T M of the lipid bilayer as the phospholipids became further disordered and possess more motional freedom [19,20].…”

“…In the current study, it also postulated that the second process represents intercalation of each drug, forming a drug/phospholipid complex [22,23] as drugs did not dissociate completely from the membrane as evidenced by the residual response in SPR following exposure to the drug. It has been proposed that formation of drug/phospholipid complexes mimics phospholipidosis [14,19,23], a type of lipid storage disorder [24] which could give rise to the observed defects.…”

Biophotonic techniques for manipulation and characterization of drug delivery nanosystems in cancer therapy

“…A relative number of papers describe the use of AFM in the study of the interaction between the drug and the lipid membranes. The aim of these researches is mainly to understand the properties of biomembranes and the correlated processes such as cell adhesion, membrane fusion and drug membrane interaction [102][103][104]. Anabousi et al [105] imaged the binding of transferrin (Tf) to liposomes, with three different coupling methods, for producing drug delivery systems that specifically bind to transferrin receptors (TfR), over expressed on cell types of therapeutic interest like tumor cells.…”

Drug–Membrane Interactions: Molecular Mechanisms Underlying Therapeutic and Toxic Effects of Drugs

“…Examples include cyclosporine [41], steroids [42], trifluoroperazine [43], and antibiotics like aminoglycosides [44,45] or macrolides (azithromycin) [46][47][48][49][50][51][52][53]. This latter compound has also shown to markedly inhibit endocytosis [52,53], probably by interacting with lipids, modifying biophysical properties of membrane and affecting membrane's dynamics in living cells [46,47]. The membrane interactions, as a part of the mechanism of action, is further shown for amphiphilic drugs like cisplatin [54-59], amphotericin B [60, 61], and antimicrobial peptides such as magainin, cecropin, and defensin [62-68], for which no protein receptors have been identified.…”