Synthesis and dynamics of deuterium labeled acylceramides Tomáš Havrišák 1 , Ferdinand Fandrei 2 , Lukáš Opálka 1 , Oskar Engberg 2 , Albert A. Smith 2 , Petra Pullmannová 1 , Norbert Kučerka 3 , Veronika Ondrejčeková 1 , Bruno Demé 4 , Lucie Nováková 1 , Miloš Steinhart 5 , Daniel Huster 2 , Kateřina Vávrová 1 1 Charles University, Czech Republic 2 University of Leipzig, Germany 3 Comenius University in Bratislava, Slovakia 4 Institut Laue-Langevin, France 5 Czech Academy of Science in Prague, Czech Republic Acylceramides are essential part of human skin barrier, their presence is necessary for formation of long periodicity lamellar phase and corneocyte lipid envelope which are responsible for correct barrier function of skin. However, there is still little known about the dynamics of these molecules in skin. One of the methods to study molecular dynamics is solid state NMR analysis, which requires specific labeling in molecule. Fig. 1: Molecule of acylceramide with deuteratin in rear (A) and front (B) half of ultralong chain In this project we focused on synthesis of acylceramides with deuteration in their ultralong chain (C 2 – C 16 and C 17 – C 32 ). Synthesis started with perdeuterated γ-butyrolactone and 1,12-dibromododecane which were modified and connected via a Wittig reaction providing 16C deuterated fragment. After further modifications, this fragment underwent second Wittig reaction with 16C nondeuterated molecule, providing thirty-two carbon long chain with deuteration in frontal or rear part. This precursor was then esterified with linoleic acid and connected with sphingosine to form final molecules of acylceramides. Whole synthesis was performed in seventeen steps with yield of 2 % for aclyceramide with deuteration in the rear half of ultralong chain (A) and in twelve steps with yield of 0,5 % for acylceramide with deuteration in front half (B). These modified acylceramides were then mixed with other skin lipids and studied in model lipid membranes. These model membranes showed different molecular dynamics of the ultralong chain based on deuterium labeling: rear half of chain is more mobile (27 % of crystalline phase) compared to front part (53 % of crystalline phase). Compared to linoleate chain (0 % of crystalline phase) the rigidity of chain is increased from linoleate chain towards sphingoide head of acylceramide. This information led to suggestion of new model of organization of lipids in long periodicity lamellar phase in stratum corneum. This work was supported by the Czech Science Foundation (22-20839K) and project “Grant Schemes at CU’’ (CZ. 02.2.69/0.0/0.0/19_073/0016935).
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