Screening of plant extracts for human tyrosinase inhibiting effects / M. Kim in INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Vol. 34, N° 2 (04/2012)  

[article]  inINTERNATIONAL JOURNAL OF COSMETIC SCIENCE > Vol. 34, N° 2 (04/2012) . - p. 202-208 Titre : Screening of plant extracts for human tyrosinase inhibiting effects : https://onlinelibrary.wiley.com/doi/10.1111/j.1468-2494.2012.00704.x Type de document : texte imprimé Auteurs : M. Kim, Auteur ; K. Song, Auteur ; H. G. Kim, Auteur ; J.-S. Koh, Auteur ; Yong Chool Boo, Auteur Année de publication : 2012 Article en page(s) : p. 202-208 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Anti tyrosinase Coumarique, Acide Extraits de plantes:Extraits (pharmacie) Mélanine Pigmentation de la peau Vaccinium bracteatum Thunberg Index. décimale : 668.5 Parfums et cosmétiques Résumé : Screening for tyrosinase (TYR) inhibitors potentially useful for control of skin pigmentation has been hampered by the limited availability of human TYR. To overcome this hurdle, we have established human embryonic kidney (HEK293)-TYR cells that constitutively express human TYR. In the current study, we assayed human TYR inhibition activities of 50 plant extracts using the lysates of transformed HEK293-TYR cells. The strongest inhibition of human TYR was shown by the extract of Vaccinium bracteatum Thunberg, followed by the extract of Morus bombycis Koidzumi. The former extract did not inhibit mushroom TYR activity whereas significant inhibition was observed with the latter extract, demonstrating the importance of using human TYR in the screening for human TYR inhibitors. Upon liquid-liquid partitioning of the extract from V. bracteatum, the active constituents were enriched in the ethyl acetate fraction, and the subsequent preparatory thin-layer chromatography identified p-coumaric acid (PCA) as the main active constituent. The hypo-pigmentation of PCA was verified in the MelanoDermâ„¢ Skin Model. This study demonstrates that transformed HEK293-TYR cells could expedite the discovery of human TYR-specific inhibitors from natural sources which might be useful in the control of skin pigmentation. Note de contenu : - Plant extracts - Fractionation of the extract from Vaccinium bracteatum Thunberg - HPLC analysis - Preparation of cell-free extracts from transformed HEK293-TYR cells - In vitro assay for TYR activity - Pigmentation assay in a reconstructed skin model - Statistical analysis DOI : 10.1111/j.1468-2494.2012.00704.x En ligne : https://onlinelibrary.wiley.com/doi/10.1111/j.1468-2494.2012.00704.x Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=14393 [article]

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Single and double bubble tubular film extrusion of polybutylene terephthalate / K. Song in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 2 (06/2000)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XV, N° 2 (06/2000) . - p. 157-165 Titre : Single and double bubble tubular film extrusion of polybutylene terephthalate Type de document : texte imprimé Auteurs : K. Song, Auteur ; J. L. White, Auteur Année de publication : 2000 Article en page(s) : p. 157-165 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : An experimental study of film formation and structure development of polybutylene terephthalate (PBT) in single and double bubble tubular film extrusion processes is presented. PBT was found largely stable in the first stage. In the second stage, the bubble was unstable and biaxial inflation was achieved only with a blow-up ratio of one. The sources of second bubble instabilities were related to the crystalline nature of the first bubble being inflated in the second stage. The structure and properties in the films varied substantially with processing conditions. While the first bubble had poorly ordered α-structure, the double bubble possessed oriented polymorphic texture. The second deformation that induced high film-line stress favored the formation of a stable β phase. The mechanical behavior of the films reflected the crystal perfection as well as orientation in the films. Note de contenu : - EXPERIMENTAL : Materials and film formation - Wide angle X-ray diffraction - Differential scanning calorimeter - Refractive index - Tensile test - RESULTS : Tubular film extrusion process - WAXS flat film photographs - WAXS diffractometer scans - Differential scanning calorimetry - WAXS pole figures - Refractive indices - Mechanical properties - DISCUSSION : Stability of tubular film extrusion - Structural character as a function of processing - Crystalling melting behavior and crystallinity - Crystalline orientation - Optical behavior - Mechanical behavior DOI : 10.3139/217.1581 En ligne : https://drive.google.com/file/d/1mVSh-IHGjy8_O7-uZTKtUNQLpIW97ONk/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16054 [article]

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