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Bile Acid Derivatives from a Sponge-Associated Bacterium Psychrobacter sp.
Huayue Li,이혜자,Eun Sook Yoo,Lee Chong-O,Pramod B. Shinde,홍종기,최상호,정지형 대한약학회 2009 Archives of Pharmacal Research Vol.32 No.6
In our search for bioactive metabolites from a marine sponge-associated bacterium Psychrobacter sp., a new bile acid derivative (1), which was assumed to be an artifact, were isolated along with six known (2-7) compounds by bioactivity-guided fractionation. Elucidation of the structure of the new compound was done using a combination of NMR (1H, 13C, HMBC, HSQC, and COSY) and MS spectroscopy. Compound 1 exhibited moderate suppressive effects on both NO and IL-6 production at a concentration of 200 μM (87.3 μg/mL) without significant cytotoxicity against cells. Compounds 2-5 and 7 showed selective inhibitory activity against several human pathogenic bacterial strains at the low concentration of 30 μg/well. In a cytotoxicity evaluation, only compound 7 showed mild cytotoxicity against five human solid tumor cell lines (A-549, SK-OV-3, SK-MEL-2, XF-498, and HCT-15) with ED50 values in the range of 11-14 μg/mL.
ω-MODULES OVER COMMUTATIVE RINGS
Huayu Yin,Fanggui Wang,Xiaosheng Zhu,Youhua Chen 대한수학회 2011 대한수학회지 Vol.48 No.1
Let R be a commutative ring and let M be a GV -torsionfree R-module. Then M is said to be a w-module if Ext<수식> for any J ∈ GV (R), and the ω-envelope of M is defined by Mω = {x ∈E(M)ㅣJx ⊆ M for some J ∈ GV (R)}. In this paper, ω-modules over commutative rings are considered, and the theory of ω-operations is de-veloped for arbitrary commutative rings. As applications, we give some characterizations of ω-Noetherian rings and Krull rings.
Customer-based Concentration and Firm Innovation
Huayu Shen,Ning Xia,Jun Zhang 한국증권학회 2018 Asia-Pacific Journal of Financial Studies Vol.47 No.2
Based on a sample of listed companies in Shanghai and Shenzhen, China from 2007 to 2015, this paper discusses the relationship between customer concentration and corporate innovation. The results show that this relationship is nonlinear and U-shaped. In addition, this paper finds that when the bargaining power of large customers is weak and the level of supply chain integration is high, the U-shaped relationship becomes more significant. Additional analyses show that the U-shaped relationship between customer concentration and corporate innovation is more significant for non-state-owned enterprises and those with lower levels of cash holding.
Solution Structure of a Sponge-Derived Cystine Knot Peptide and Its Notable Stability
Li, Huayue,Su, Mingzhi,Hamann, Mark T.,Bowling, John J.,Kim, Hyung Sik,Jung, Jee H. American Chemical Society and American Society of 2014 Journal of natural products Vol.77 No.2
<P>A novel cystine knot peptide, asteropsin E (ASPE), was isolated from an <I>Asteropus</I> sp. marine sponge. The primary, secondary, and tertiary structures of ASPE were determined by high-resolution 2D NMR spectroscopy (900 MHz). With the exception of an <I>N</I>-terminal modification, ASPE shares properties with the previously reported asteropsins A–D, that is, the absence of basic residues, a highly acidic nature, conserved structurally important residues (including two <I>cis</I>-prolines), and a highly conserved tertiary structural framework. ASPE was found to be remarkably stable to gastrointestinal tract enzymes (chymotrypsin, elastase, pepsin, and trypsin) and to human plasma.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jnprdf/2014/jnprdf.2014.77.issue-2/np400899a/production/images/medium/np-2013-00899a_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/np400899a'>ACS Electronic Supporting Info</A></P>