Self-assembly and biological activities of ionic liquid crystals derived from aromatic amino acids. Issue 31 (25th July 2018)

• Record Type: Journal Article
• Authors: Neidhardt, Manuel M.; Schmitt, Katharina; Baro, Angelika; Schneider, Carmen; Bilitewski, Ursula; Laschat, Sabine
• Is Part Of: Physical chemistry chemical physics. Volume 20:Issue 31(2018)
• Page Start: 20371
• Page End: 20381
• Publication Date: 2018-07-25
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c8cp03404d
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Does the mesomorphic behaviour ofl -amino acid-based ILCs correlate with biological activity? Abstract : The self-assembly of amino acid-derived ionic liquid crystals (ILCs) into lamellar or micellar-like aggregates suggests that they might interact with biological membranes. To get some insight, guanidinium chlorides derived from the naturall -amino acids phenylalanine (Phe), tyrosine (Tyr) and 3, 4-dihydroxyphenylalanine (DOPA) were synthesized and their mesomorphic properties were investigated via polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (SAXS, WAXS). Mesophase types depended on the number of alkoxy side chains. Phe- and Tyr-based ILCs with one and two side chains, respectively, self-assembled into smectic A bilayers (SmA2 ), while Dopa-derived ILCs with three side chains formed columnar (Colh ) mesophases. The mesophase ranges for Phe ILCs increased steadily with side chain length, for Tyr- and Dopa-based ILCs, however, size matching effects were observed. To clarify whether the mesomorphic behaviour has an impact on biological properties, cytotoxic and antibacterial activities of the ILCs were studied. Phe and Tyr ILCs exhibited much higher cytotoxicities (against the L-929 mouse fibroblast cell line) and/or antibacterial activities (against Staphylococcus aureus ) than Dopa ILCs, which were mostly inactive. Furthermore, within each series, the side chain length largely influenced the biological activity. Thus, the bulk mesophase behaviour appeared to correlate with the biological properties, in particular, the interactions with membranes, as shown by measuring the intracellular Ca 2+ concentration in human monocytic U937 cells after treatment with the amino acid-based ILCs.