Browsing by Subject "Silica"

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    Mouse and human islets survive and function after coating by biosilicification
    (American Physiological Society, 2013-11-15) Jaroch, David B.; Lu, Jing; Madangopal, Rajtarun; Stull, Natalie D.; Stensberg, Matthew; Shi, Jin; Kahn, Jennifer L.; Herrera-Perez, Ruth; Zeitchek, Michael; Sturgis, Jennifer; Robinson, J. Paul; Yoder, Mervin C.; Porterfield, D. Marshall; Mirmira, Raghavendra; Rickus, Jenna L.; Medicine, School of Medicine
    Inorganic materials have properties that can be advantageous in bioencapsulation for cell transplantation. Our aim was to engineer a hybrid inorganic/soft tissue construct by inducing pancreatic islets to grow an inorganic shell. We created pancreatic islets surrounded by porous silica, which has potential application in the immunoprotection of islets in transplantation therapies for type 1 diabetes. The new method takes advantage of the islet capsule surface as a template for silica formation. Mouse and human islets were exposed to medium containing saturating silicic acid levels for 9-15 min. The resulting tissue constructs were then cultured for up to 4 wk under normal conditions. Scanning electron microscopy and energy dispersive X-ray spectroscopy was used to monitor the morphology and elemental composition of the material at the islet surface. A cytokine assay was used to assess biocompatibility with macrophages. Islet survival and function were assessed by confocal microscopy, glucose-stimulated insulin release assays, oxygen flux at the islet surface, expression of key genes by RT-PCR, and syngeneic transplant into diabetic mice.
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    Total Synthesis of Naturally Occurring 5,7,8-Trioxygenated Homoisoflavonoids
    (American Chemical Society, 2020-05-06) Kwon, Sangil; Lee, Sanha; Heo, Myunghoe; Lee, Bit; Fei, Xiang; Corson, Timothy W.; Seo, Seung-Yong; Ophthalmology, School of Medicine
    Homoisoflavonoids are in the subclass of the larger family of flavonoids but have one more alkyl carbon than flavonoids. Among them, 5,7,8-trioxygenated homoisoflavonoids have not been extensively studied for synthesis and biological evaluation. Our current objective is to synthesize 2 5,7,8-trioxygenated chroman-4-ones and 12 5,7,8-trioxygenated homoisoflavonoids that have been isolated from the plants Bellevalia eigii, Drimiopsis maculata, Ledebouria graminifolia, Eucomis autumnalis, Eucomis punctata, Eucomis pallidiflora, Chionodoxa luciliae, Muscari comosum, and Dracaena cochinchinensis. For this purpose, 1,3,4,5-tetramethoxybenzene and 4'-benzyloxy-2',3'-dimethoxy-6'-hydroxyacetophenone were used as starting materials. Asymmetric transfer hydrogenation using Noyori's Ru catalyst provided 5,7,8-trioxygenated-3-benzylchroman-4-ones with R-configuration in high yield and enantiomeric excess. By selective deprotection of homoisoflavonoids using BCl3, the total synthesis of natural products including 10 first syntheses and three asymmetric syntheses has been completed, and three isomers of the reported dracaeconolide B could be provided. Our research on 5,7,8-trioxygenated homoisoflavonoids would be useful for the synthesis of related natural products and pharmacological applications.