title: Synthesis, characterization and thermotropic phase behavior of a homologous series of N-acyl-L-alaninols and interaction of N-myristoyl L-alaninol with dimyristoylphosphatidylcholine.
abstract: N-acylethanolamines (NAEs) and their precursors, N-acylphosphatidylethanolamines are present in the cell membranes of a variety of species and exhibit interesting biological properties. N-acyl-L-alaninols (NAAOHs) are chiral homologues of NAEs and reduced forms of N-acyl-L-alanines (NAAs) and were reported to induce apoptosis in human lymphocytes. In the present study, we have synthesized and characterized a homologous series of N-acyl-L-alaninols (n=9-20). In DSC studies in the dry as well as hydrated states NAAOHs with different chain lengths showed single sharp transitions similar to N-acyl-L-alanines. Transition enthalpies (ΔHt) and entropies (ΔSt) of NAAOHs are linearly dependent on the acyl chain length in both dry and hydrated states. Powder X-ray diffraction studies showed that the d-spacings of NAAOHs exhibit linear dependence on the chain length and the incremental increase in the d values suggest that they may be packed in a tilted bilayer pattern. Studies on the interaction of N-myristoyl L-alaninol (NMAOH) with DMPC revealed that the two amphiphiles mix well up to 45 mol% of NMAOH, whereas phase separation is observed at higher contents of the alaninol. Transmission electron microscopic studies show that the NMAOH:DMPC (45:55, mol/mol) mixture forms unilamellar vesicles of about 120-150 nm in diameter.
authors.affiliation: School of Chemistry, University of Hyderabad, Hyderabad 500 046, India.
authors.forename: D
authors.initials: D
authors.lastname: Sivaramakrishna
authors.affiliation: School of Chemistry, University of Hyderabad, Hyderabad 500 046, India. Electronic address: mjswamy@uohyd.ac.in.
authors.forename: Musti J
authors.initials: MJ
authors.lastname: Swamy
mesh_terms: D000409:Alanine / Q000031:analogs & derivatives* / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D002478:Cells, Cultured; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D006801:Humans; D046529:Microscopy, Electron, Transmission; D009227:Myristic Acids / Q000737:chemistry*; D033362:Powder Diffraction; D013816:Thermodynamics
chemical_list: D009227:Myristic Acids; C405765:N-myristoyl-alaninol; D000409:Alanine; D004134:Dimyristoylphosphatidylcholine
keywords: Differential scanning calorimetry; Fluorescence spectroscopy; N-acyl-l-alaninol; Phase transition; Powder X-ray diffraction; Transmission electron microscopy