Browsing by Author "Lee, I-Chi"

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Deuterium-isotope study on the reductive ring opening of benzylidene acetals
(2011)
Lee, I-Chi
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Zulueta, Medel Manuel L.
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Shie, Chi-Rung
;
Arco, Susan D.
;
Hung, Shang-Cheng
Specific deuterated reference compounds were prepared to probe the stereoselectivity of the reductive ring opening of carbohydrate-based benzylidene-type acetals. AlD(3) revealed a retentive stereoselectivity probably through the rare S(N)i (internal nucleophilic substitution) mechanism. An S(N)1-like mechanism occurs in the acid-promoted regioselective BD(3)center dot THF- or Et(3)SiD-reductive ring opening.
DIFFERENTIATION OF NEURAL STEM/PROGENITOR CELLS USING LOW-INTENSITY ULTRASOUND
(2014-09-01)
Lee, I-Chi
;
Lo, Tsu-Lin
;
Young, Tai-Horng
;
Li, Yi-Chen
;
Chen, Nelson G.
Herein, we report the evaluation of apoptosis, cell differentiation, neurite outgrowth and differentiation of neural stem/progenitor cells (NSPCs) in response to low-intensity ultrasound (LIUS) exposure. NSPCs were cultured under different conditions, with and without LIUS exposure, to evaluate the single and complex effects of LIUS. A lactic dehydrogenase assay revealed that the cell viability of NSPCs was maintained with LIUS exposure at an intensity range from 100 to 500 mW/cm(2). Additionally, in comparison with no LIUS exposure, the cell survival rate was improved with the combination of medium supplemented with nerve growth factor and LIUS exposure. Our results indicate that LIUS exposure promoted NSPC attachment and differentiation on a glass substrate. Neurite outgrowth assays revealed the generation of longer, thicker neurites after LIUS exposure. Furthermore, LIUS stimulation substantially increased the percentage of differentiating neural cells in NSPCs treated with nerve growth factor in comparison with the unstimulated group. The high percentage of differentiated neural cells indicated that LIUS induced neuronal networks denser than those observed in the unstimulated groups. Furthermore, the release of nitric oxide, an important small-molecule neurotransmitter, was significantly upregulated after LIUS exposure. It is therefore reasonable to suggest that LIUS promotes the differentiation of NSPCs into neural cells, induces neurite outgrowth and regulates nitric oxide production; thus, LIUS may be a potential candidate for NSPC induction and neural cell therapy. (E-mail: iclee@mail.cgu.edu.tw or yingchih@gate.sinica.edu.tw) (C) 2014 World Federation for Ultrasound in Medicine & Biology.
Synthesis of a Furanosyl-pyranone Derivative Related to the Tri-O-heterocyclic Core of Herbicidins
(2012-03-01)
Hsu, Ching-Yun
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Lee, I-Chi
;
Lico, Larry S.
;
Uang, Biing-Jiun
;
Hung, Shang-Cheng
A new compound that is structurally related to the undecose ring structure of herbicidins has been prepared. The synthesis of this novel furanosyl-pyranone derivative was made possible through the regioselective reductive ring-opening of a 3,5-O-benzylidene-D-xylofuranose and the hetero-Diels-Alder reaction of an aldehyde and a Danishefsky-type diene. The highly functionalized pyranone derivative can be a useful precursor for the synthesis of herbicidins.