Behavior of 1-Deoxy-, 3-Deoxy- and N-Methyl-Ceramides in Skin Barrier Lipid Models

Andrej Kováčik,Ludmila Pavlíková,Kateřina Vávrová,Jaroslav Maixner,Petra Pullmannová

doi:10.1038/s41598-020-60754-4

Andrej Kováčik, Ludmila Pavlíková + Show 3 more

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https://doi.org/10.1038/s41598-020-60754-4

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Abstract

Ceramides (Cer) are essential components of the skin permeability barrier. To probe the role of Cer polar head groups involved in the interfacial hydrogen bonding, the N-lignoceroyl sphingosine polar head was modified by removing the hydroxyls in C-1 (1-deoxy-Cer) or C-3 positions (3-deoxy-Cer) and by N-methylation of amide group (N-Me-Cer). Multilamellar skin lipid models were prepared as equimolar mixtures of Cer, lignoceric acid and cholesterol, with 5 wt% cholesteryl sulfate. In the 1-deoxy-Cer-based models, the lipid species were separated into highly ordered domains (as found by X-ray diffraction and infrared spectroscopy) resulting in similar water loss but 4–5-fold higher permeability to model substances compared to control with natural Cer. In contrast, 3-deoxy-Cer did not change lipid chain order but promoted the formation of a well-organized structure with a 10.8 nm repeat period. Yet both lipid models comprising deoxy-Cer had similar permeabilities to all markers. N-Methylation of Cer decreased lipid chain order, led to phase separation, and improved cholesterol miscibility in the lipid membranes, resulting in 3-fold increased water loss and 10-fold increased permeability to model compounds compared to control. Thus, the C-1 and C-3 hydroxyls and amide group, which are common to all Cer subclasses, considerably affect lipid miscibility and chain order, formation of periodical nanostructures, and permeability of the skin barrier lipid models.

Highlights

Mammalian skin protects the body from external threats, such as chemicals and ultraviolet light, and prevents excessive water loss
The studied Cer analogs were synthesized from the respective sphingoid bases (1-deoxy-sphingosine, or 3-deoxy-sphingosine, or N-methylsphingosine) and lignoceric acid (LIG) using WSC and HOBt18 in the following yields: 94% for 1-deoxy-Cer, 69% for 3-deoxy-Cer and 71% for N-Me-Cer (1H and 13C NMR spectra are shown in Supporting Fig. S1)
The synthesized unnatural Cer analogs along with the parent sphingosine-based Cer were used for the preparation of the stratum corneum (SC) lipid models composed of Cer/LIG/Chol in a 1:1:1 molar ratio, with an addition of 5 wt% CholS19

Summary

Introduction

Mammalian skin protects the body from external threats, such as chemicals and ultraviolet light, and prevents excessive water loss. Additional hydroxyls in Cer at C-4 (phytosphingosine Cer) or C-6 positions (6-hydroxyCer) modulate the lipid miscibility, lamellar arrangement and permeability of model SC lipid mixtures[7,8,9,10], along with the correct acyl chain length[11,12] or sphingosine chain length of Cer[13,14]. Topical supplementation of skin lipids in diseases such as atopic dermatitis or ichthyoses is an established therapeutic approach Such Cer-dominant lipids are safe, can prevent inflammation in atopic dermatitis and have corticoid sparing effect We focus on the role of the polar head groups that are common to all Cer subclasses, i.e., C-1 hydroxyl, C-3 hydroxyl and amide hydrogen, in skin lipid models. The barrier properties of the SC lipid models were studied using four permeability markers: water loss, flux of theophylline (TH), flux of indomethacin (IND), and electrical impedance

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