BIOORGANIC CHEMISTRY
·
2026
·
IF 5.1
Xincheng Sun,Changkang Li,Jimei Liu,Ridao Chen,Dawei Chen,Jungui Dai
The 6/5/6 to 6/6/5 ring system rearrangement from indole alkaloids strictosidine ( 1 ) and strictosamide ( 2 ) to quinoline alkaloid pumiloside ( 3 ) is an essential but unelucidated process in the biosynthesis of camptothecin, especially, the intermediates involved in the process have not been identified. Herein, the nonenzymatic conversions including spontaneous reaction from 1 to 2 , and light- or flavin-catalyzed skeletal rearrangement from 2 to 3 have been discovered. Particularly, the crucial biosynthetic intermediate strictosamide ketolactam ( 2a ) with dicarbonyl nine-membered ring involved in the conversion from 2 to 3 is obtained and structurally characterized. Moreover, the successive conversion from 1 to 3 is achieved in Nicotiana benthamiana . These findings not only provide a new insight into and better understanding for the biosynthesis of camptothecin with rare nonenzymatic reactions, also lay the foundation for further elucidation of the biosynthetic pathway of camptothecin.
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高影响因子
JOURNAL OF SOLID STATE ELECTROCHEMISTRY
·
2021
·Vol. 25
·期 6
·1847-1859
·
IF 2.647
Li Chunxia,Guo Xin,Du Hongmei,Zhao Jinsheng,Liu Lixia,Yuan Qing,Fu Chonggang
Two novel donor-acceptor (D-A)-conjugated polymers, poly[(thiophene-2,5-yl)-((benzo[1,2-b:6,5-b′]dithiophene-4,5-dione)-2,7-yl)] (PTDT) and poly[((2,3-dihydrothieno[3,4-b] [ 1 , 2 ]dioxine)-5,7-diyl)-((benzo[1,2-b:6,5-b′]dithiophene-4,5-dione)-2,7-diyl)] (PTDO), have been synthesized with the same acceptor unit of benzo[1,2-b:6,5-b′]dithiophene-4,5-dione and different donor units of thiophene (Th) and 3,4-ethylenedioxothiphene (EDOT), respectively. And then, two composites (PTDT@C and PTDO@C) are made by coating the polymers on the surface of active carbon with an in situ method, which are used as the electrode materials of lithium-ion battery. The reversible capacities of PTDT@C and PTDO@C are 246.9 and 322.3 mAh g −1 at 0.1 A g −1 after 300 cycles running, respectively. By deducing the capability contribution of pure carbon, the theoretical capacities of the pure polymers are calculated to be 596 and 991 mAh g −1 , respectively, for PTDT and PTDO, which correspond to the lithium storage number of 6.7 and 13.3, respectively, for the least repeating unit of the polymers. With the help of theoretical calculations, the underlying mechanisms for the different electrochemical performances of the polymers are discussed and revealed. The structure-activity relationship discussed in this work may provide the design principle for the construction of the D-A-type polymers used as high-capacity electrode materials for organic rechargeable batteries.
研究领域:
材料科学
·
电化学
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DOI
高影响因子
ACS Omega
·
2019
·
IF 2.584
Kai Zhang,Cai-Shui Wang,Qian Zhou,Hai-Mu Ye
Biodegradable poly(1,4-butylene adipate) (PBA) has been highlighted of distinct polymorphism and receives extensive research by adding nucleating agents. Usually, only a single nucleating mechanism is proposed for each composite system, which should not be sufficient. In present work, 1,2,3-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol sorbitol (NX), a commercial sorbitol derivative, was incorporated into the PBA matrix to regulate the crystallization behavior. It is found that the non-isothermal crystallization temperature rises first and then declines, but the α-form crystal-forming ability becomes stronger with the increasing NX content, which is due to the limited solubility of NX in PBA. When NX is totally dissolved, the specific butterfly molecular shape of NX helps PBA chains form the gauche conformation, simultaneously promoting the crystallization rate and α crystal formation. However, once the NX content is ≥1%, crystallites of NX appear and play as physical cross-linking points for PBA chains; then, the mobility restriction becomes the major mechanism, which would slow down the crystallization rate but significantly enhance the formation of the α-form crystal-forming ability. PBA/NX composites possess a considerably lower degradation rate than neat PBA. Thus, this work demonstrates a novel additive of the dual mechanism to regulate the crystallization behavior and further the degradation rate of PBA.
研究领域:
材料科学
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聚合物化学
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生物可降解聚合物
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Biomedical Materials
·
2011
·Vol. 6
·期 5
·055008
·
IF 2.467
Yan Wei,Xuehui Zhang,Yu Song,Bing Han,Xiaoyang Hu,Xinzhi Wang,Yuanhua Lin,Xuliang Deng
In recent years, interest in magnetic biomimetic scaffolds for tissue engineering has increased considerably. The aim of this study is to develop magnetic biodegradable fibrous materials with potential use in bone regeneration. Magnetic biodegradable Fe3O4/chitosan (CS)/poly vinyl alcohol (PVA) nanofibrous membranes were achieved by electrospinning with average fiber diameters ranging from 230 to 380 nm and porosity of 83.9–85.1%. The influences of polymer concentration, applied voltage and Fe3O4 nanoparticles loading on the fabrication of nanofibers were investigated. The polymer concentration of 4.5 wt%, applied voltage of 20 kV and Fe3O4 nanoparticles loading of lower than 5 wt% could produce homogeneous, smooth and continuous Fe3O4/CS/PVA nanofibrous membranes. X-ray diffraction (XRD) data confirmed that the crystalline structure of the Fe3O4, CS and PVA were maintained during electrospinning process. Fourier transform infrared spectroscopy (FT-IR) demonstrated that the Fe3O4 loading up to 5 wt% did not change the functional groups of CS/PVA greatly. Transmission electron microscopy (TEM) showed islets of Fe3O4 nanoparticles evenly distributed in the fibers. Weak ferrimagnetic behaviors of membranes were revealed by vibrating sample magnetometer (VSM) test. Tensile test exhibited Young's modulus of membranes that were gradually enhanced with the increase of Fe3O4 nanoparticles loading, while ultimate tensile stress and ultimate strain were slightly reduced by Fe3O4 nanoparticles loading of 5%. Additionally, MG63 human osteoblast-like cells were seeded on the magnetic nanofibrous membranes to evaluate their bone biocompatibility. Cell growth dynamics according to MTT assay and scanning electron microscopy (SEM) observation exhibited good cell adhesion and proliferation, suggesting that this magnetic biodegradable Fe3O4/CS/PVA nanofibrous membranes can be one of promising biomaterials for facilitation of osteogenesis.
研究领域:
生物医学工程
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材料科学
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组织工程
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高影响因子
CELL
·
2022
·
IF 66.85
Shu-Hsien Sheu,Srigokul Upadhyayula,Vincent Dupuy,Song Pang,Fei Deng,Jinxia Wan,Deepika Walpita,H. Amalia Pasolli,Justin Houser,Silvia Sanchez-Martinez,Sebastian E. Brauchi,Sambashiva Banala,Melanie Freeman,C. Shan Xu,Tom Kirchhausen,Harald F. Hess,Luke Lavis,Yulong Li,Séverine Chaumont-Dubel,David E. Clapham
Summary Chemical synapses between axons and dendrites mediate neuronal intercellular communication. Here, we describe a synapse between axons and primary cilia: the axo-ciliary synapse. Using enhanced focused ion beam-scanning electron microscopy on samples with optimally preserved ultrastructure, we discovered synapses between brainstem serotonergic axons and the primary cilia of hippocampal CA1 pyramidal neurons. Functionally, these cilia are enriched in a ciliary-restricted serotonin receptor, the 5-hydroxytryptamine receptor 6 (5-HTR6). Using a cilia-targeted serotonin sensor, we show that opto- and chemogenetic stimulation of serotonergic axons releases serotonin onto cilia. Ciliary 5-HTR6 stimulation activates a non-canonical G αq/11 -RhoA pathway, which modulates nuclear actin and increases histone acetylation and chromatin accessibility. Ablation of this pathway reduces chromatin accessibility in CA1 pyramidal neurons. As a signaling apparatus with proximity to the nucleus, axo-ciliary synapses short circuit neurotransmission to alter the postsynaptic neuron’s epigenetic state.
研究领域:
神经科学
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细胞生物学
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分子生物学
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高影响因子
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