Joo-Hoon Park

Novel bent-shaped liquid crystalline compounds: 1. Synthesis and structure analysis of dimesogenic compounds with azo units

Abstract A new series of bent-shaped liquid crystalline compounds (2An), which were composed of two identical mesogens (azobenzene-type), terminal alkyloxy chains (n=6, 8, 10, 12) and 2-hydroxy-1,3-dioxypropylene as central linking unit, have been prepared. Their mesomorphic properties were characterized by polarized light microscopy, differential thermal analysis, and X-ray diffraction (XRD). For 2An series, n=8, 10 and 12 compounds showed enantiotropic SmC phase, but n=6 compound did not show liquid crystal phase, as was confirmed by the XRD patterns.

Novel bent-shaped liquid crystalline compounds II. Synthesis and properties of the 1,3-bis{4-[4-(4-alkyloxybenzoyloxy)benzylidene]aminophenoxy}propan-2-ols

A series of new symmetric dimer compounds was synthesized, constaining 2-hydroxy-1,3-dioxypropylene as the central linkage and terminal alkyl chains with different lengths. The chemical structures of the liquid crystal dimers (2ES-n) were examined by FTIR and 1H NMR spectroscopy. Their mesomorphism, thermodynamic properties and optical textures were investigated by differential scanning calorimetry, polarizing optical microscope and X-ray diffraction. For homologues with terminal propyloxy and butyloxy chains, no liquid crystalline phase was observed. Homologues with pentyloxy and hexyloxy terminal chains showed nematic phases, while those with heptyloxy, octyloxy, nonyloxy and decyloxy terminal chains displayed nematic phases and smectic phases. The results confirmed that the liquid crystalline phase changes from nematic to smectic as the terminal chain length increases.

Olibanum Extract Inhibits Vascular Smooth Muscle Cell Migration and Proliferation in Response to Platelet-Derived Growth Factor

Olibanum (Boswellia serrata) has been shown to have anti-inflammatory, anti-arthritic and anti-cancer effects. This study determined the role of a water extract of olibanum in platelet-derived growth factor (PDGF)-stimulated proliferation and migration of rat aortic smooth muscle cells (RASMCs). PDGF-BB induced the migration and proliferation of RASMCs that were inhibited by olibanum extract in a dose-dependent manner. The PDGF-BB-increased phosphorylation of p38 mitogen-activated protein kinase (MAPK); the heat shock protein (Hsp) 27 was significantly inhibited by the olibanum extract. The effects of PDGF-BB-induced extracellular signal-regulated kinase1/2 was not altered by the olibanum extract. Treatment with olibanum extract inhibited PDGF-BB-stimulated sprout out growth of aortic rings. These results suggest that the water extract of olibanum inhibits PDGF-BB-stimulated migration and proliferation in RASMCs as well as sprout out growth, which may be mediated by the inhibition of the p38 MAPK and Hsp27 pathways.

Chrysanthemum boreale Makino essential oil induces keratinocyte proliferation and skin regeneration

We investigated the effect of essential oil from the flower of Chrysanthemum boreale Makino (CBMEO) on growth of human keratinocytes (HaCaTs) and explored a possible mechanism for this response. CBMEO was extracted using the steam distillation method. CBMEO contained a total of 33 compounds. CBMEO stimulated HaCaT proliferation (EC50, 0.028 μg/mL) and also induced phosphorylation of Akt and ERK1/2 in HaCaTs (EC50, 0.007 and 0.005 μg/mL, for phosphorylated Akt and ERK1/2, respectively). Moreover, CBMEO promoted wound closure in the dorsal side skin of rat tail. This study demonstrated that CBMEO can stimulate growth of human skin keratinocytes, probably through the Akt and ERK1/2 pathways. Therefore, CBMEO may be helpful in skin regeneration and wound healing in human skin, and may also be a possible cosmetic material for skin beauty.

Chrysanthemum boreale flower floral water inhibits platelet-derived growth factor-stimulated migration and proliferation in vascular smooth muscle cells

Abstract Context: Chrysanthemum boreale Makino (Compositae) (CBM) is a traditional medicine that has been used for the prevention or treatment of various disorders; it has various properties including antioxidation, anti-inflammation, and antitumor. Objective: The present study was designed to explore the in vitro effect of CBM flower floral water (CBMFF) on atherosclerosis-related responses in rat aortic smooth muscle cells (RASMCs). Materials and methods: CBMFF was extracted from CBM flower by steam distillation and analyzed using gas chromatography–mass spectrometry. The anti-atherosclerosis activity of CBMFF was tested by estimating platelet-derived growth factor (PDGF)-BB (10 ng/mL)-induced proliferation and migration levels and intracellular kinase pathways in RASMCs at CBMFF concentrations of 0.01–100 μM and analyzing ex vivo aortic ring assay. Results: Gas chromatography–mass spectrometry showed that the CBMFF contained a total of seven components. The CBMFF inhibits PDGF-BB-stimulated RASMC migration and proliferation (IC50: 0.010 μg/mL). Treatment of RASMCs with PDGF-BB induced PDGFR-β phosphorylation and increased the phosphorylations of MAPK p38 and ERK1/2. CBMFF addition prevented PDGF-BB-induced phosphorylation of these kinases (IC50: 008 and 0.018 μg/mL, for p38 MAPK and ERK1/2, respectively), as well as PDGFR-β (IC50: 0.046 μg/mL). Treatment with inhibitors of PDGFR, P38 MAPK, and ERK1/2 decreased PDGF-BB-increased migration and proliferation in RASMCs. Moreover, the CBMFF suppressed PDGF-BB-increased sprout outgrowth of aortic rings (IC50: 0.047 μg/mL). Discussion and conclusion: These results demonstrate that CBMFF may inhibit PDGF-BB-induced vascular migration and proliferation, most likely through inhibition of the PDGFR-β-mediated MAPK pathway; therefore, the CBMFF may be promising candidate for the development of herbal remedies for vascular disorders.

Thermotropic Liquid Crystalline Dimers with Varying Alkoxy Terminal Chain Length

We have design and synthesized of homologous Series I dimers and to study the effect of molecular structure variation and change in alkoxy terminal chain length (n = 6, 7, 8) on mesomorphic properties of liquid crystals. Explore further understanding of the structure-property relationship of liquid crystal homologous Seriesl dimers having varying alkoxy terminal chain length. It was found that the decrease in crystalline phase, smectic C and nematic phase transition temperatures with increasing terminal alkoxy chain length. The molecular structures of the Seriesl dimer were characterized by Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. Their mesomorphic properties were investigated by differential scannning calorimetry (DSC) and on the hot-stage of a polarizing microscope (POM).

Liquid crystal properties of dimers having two identical terminal units and a central oxyethylene spacers

ABSTRACT Liquid crystal compounds are an important state of matter both scientifically and technologically. So we have prepared HSEO-n(n = 1,2,3,4) series shown below. In this study, in orde to acquire further understanding of the structure-property relationship of HSEO-n series, the chemical structure of the intermediates and the final products HSEO-n series was studied by fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy and the liquid crystal properties and optical textures of the HSEO-n series were characterized by differential scanning calorimetry (DSC) and polarized optical microscopy (POM).

Synthesis of Aromatic Polyketones by Direct Polycondensation Between Terephthalic Acid and Diaryl Compounds

Abstract A convenient method for the synthesis of a new series of polyarylketones with relatively high molecular weights has been investigated. The polymers were prepared readily by direct polycondensation of terephthalic acid with a series of diaryl compounds using phosphorous pentoxide/trifluoromethanesulfonic acid (w/w = 1/10), phosphorous pentoxide/methanesulfonic acid (w/w = 1/10), and aluminum chloride/phosphorous oxychloride (w/v = 1/3) as condensing agents. Among the three, the phosphorous pentoxide/trifluoromethanesulfonic acid pair was found to be most efficient and was studied in detail. The thermal and crystalline properties of the resulting polyarylketones were characterized. All of the polyketones prepared in the present study are crystalline and their glass transition temperatures and melting points depend greatly on the structure of the diaryl compounds employed.