Interaction of miltefosine with intercellular membranes of stratum corneum and biomimetic lipid vesicles

Abstract

Miltefosine (MT) is an alkylphospholipid approved for breast cancer metastasis and visceral leishmaniasis treatments, although the respective action mechanisms at the molecular level remain poorly understood. In this work, the interaction of miltefosine with the lipid component of stratum corneum (SC), the uppermost skin layer, was studied by electron paramagnetic resonance (EPR) spectroscopy of several fatty acid spin-labels. In addition, the effect of miltefosine on (i) spherical lipid vesicles of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and (ii) lipids extracted from SC was also investigated, by EPR and time-resolved polarized fluorescence methods. In SC of neonatal Wistar rats, 4% (w/w) miltefosine give rise to a large increase of the fluidity of the intercellular membranes, in the temperature range from 6 to about 50°C. This effect becomes negligible at temperatures higher that ca. 60°C. In large unilamelar vesicles of DPPC no significant changes could be observed with a miltefosine concentration 25% molar, in close analogy with the behavior of biomimetic vesicles prepared with bovine brain ceramide, behenic acid and cholesterol. In these last samples, a 25 mol% molar concentration of miltefosine produced only a modest decrease in the bilayer fluidity. Although miltefosine is not a feasible skin permeation enhancer due to its toxicity, the information provided in this work could be of utility in the development of a MT topical treatment of cutaneous leishmaniasis.

Miltefosine Increases Lipid and Protein Dynamics in Leishmania amazonensis Membranes at Concentrations Similar to Those Needed for Cytotoxicity Activity

“…As described previously, the lipid spin labels were incorporated into the Leishmania membranes first by making films of the spin labels on the bottoms of test tubes (10,11). A 1-l aliquot of a stock solution of the spin label 5-DSA in ethanol (4 mg/ml) was transferred to a glass tube, and after solvent evaporation, 50 l of a Leishmania suspension containing 10 8 cells in phosphate-buffered saline (PBS) was added to the spin-label film, followed by gentle agitation.…”

“…Electron paramagnetic resonance (EPR) spectroscopy of several fatty acid spin labels was recently employed to demonstrate that the application of MT at concentrations of up to 25 mol% in 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) vesicles subjected to a rigorous extrusion process does not alter vesicle lipid dynamics (10). Additionally, it was shown that MT causes remarkable increases in the lipid fluidity of stratum corneum membranes when measured directly in tissue but results in only a small alteration of lipid fluidity in a stratum corneum membrane model (10).…”

“…Additionally, it was shown that MT causes remarkable increases in the lipid fluidity of stratum corneum membranes when measured directly in tissue but results in only a small alteration of lipid fluidity in a stratum corneum membrane model (10). MT also causes dramatic increases of membrane fluidity in erythrocyte ghost membranes and detergent-resistant membranes (DRMs) (11).…”

Electron paramagnetic resonance (EPR) spectral components of spin-labeled lipids in saturated phospholipid bilayers: effect of cholesterol

“…[8][9][10] The presence of the terpenes L-menthol and 1,8-cineole, two potent skin permeation enhancers, in stratum corneum at 1% (w/w) or DPPC vesicles at a terpene:lipid molar ratio of 0.7:1 drastically increased the lipid fluidity, especially by transferring the spin probes from a more to a less motionally restricted spectral component in the membranes. 9,10 More recently, EPR spectra of spin labels in membrane were simulated using two-component models to study effects of the anti antileishmanial drug miltefosine in stratum corneum intercellular membranes 11 and trypanocidal action of elatol 12 as well as the toxicity of terpenes in cultured fibroblasts. 13 Since the question of the spectral components in the EPR spectra of spin-labeled lipids in membrane models of simple bilayers has not been addressed in depth, we conducted an extensive experimental study with the spin probe methyl 5-doxyl-stearate (5-DMS) in vesicles of saturated phosphatidylcholines with acyl chain lengths ranging from 16 to 22 carbon atoms and temperatures in the 10 to 78 o C range.…”

In vitro Analysis of the Effect of Alkyl-Chain Length of Anionic Surfactants on the Skin by Using a Reconstructed Human Epidermal Model

“…4 , when the permeability was greater for AS and MES with C10 to C14. It is generally known that many hydrophobic penetrants induce the fluidization of the lipid bilayer in the epidermis 26 . The stratum corneum layer in the epidermis is rich in ceramide, cholesterol, and free fatty acids 27 , and the cell membrane of the living cell layer is rich in phospholipids, triglycerides, and cholesterol.…”