Divergent Syntheses of Pyridoacridine Alkaloids via Palladium-Catalyzed Reductive Cyclization with Nitro-Biarenes

Main observation and conclusion A divergent and novel protocol for the preparation of both pyrido[2,3,4-k/]acridine and pyrido[4,3,2-k/]acridine alkaloids was d...     

Somalactams A–D: Anti-inflammatory Macrolide Lactams with Unique Ring Systems from an Arctic Actinomycete Strain

Four new PKS-NRPS-derived macrolide lactams with three unique ring fusion types were discovered from the Arctic sponge associated actinomycete Streptomyces somaliensis 1107 using a genome mining strategy. Their structures were elucidated by a combination of MS, NMR spectroscopic analysis, and single-crystal X-ray diffraction. Biosynthetically, a novel gene cluster sml consisting of three polyketide synthases and one hybrid polyketide synthase-nonribosomal peptide synthetase together with cytochrome P450s and flavin-containing monooxygenases and oxidoreductases was demonstrated to assemble the unique skeleton. Pharmacological studies revealed that compound 1 displayed a potent anti-inflammatory effect without cytotoxicity. It inhibited IL-6 and TNF-α release in the serum of LPS-stimulated RAW264.7 macrophage cells with IC₅₀ values of 5.76 and 0.18 μM, respectively, and modulated the MAPK pathway. Moreover, compound 1 alleviated LPS-induced systemic inflammation in our transgenic fluorescent zebrafish model.     

固体C60中取向运动模型与结构相变温度的计算

提出了不同温度范围内固体C₆₀分子取向运动模型,从微观上探索了取向相变发生的原因,并根据这些模型计算了面心立方及取向玻璃态的转变温度T_c及T_g,结果与实验颇相符合。     

Antimicrobial Chlorinated Carbazole Alkaloids from the Sponge-Associated Actinomycete Streptomyces diacarni LHW51701

Main observation and conclusion Four new chlorinated carbazole alkaloids,chlocarbazomycins (CCBs) A-D,were isolated from sponge associated bacterium Strepto-myc...     

微波消解-火焰原子吸收光谱法测定细梗胡枝子中6种微量元素

用浓硝酸微波消解处理样品,火焰原子吸收光谱法测定中药细梗胡枝子中Fe、Cu、Mg、Ca、Mn、Zn6种微量元素的含量。结果表明细梗胡枝子含有丰富的人体必需微量元素,元素的回收率在97.00%—108.00%之间。该方法操作简单,结果准确,是细梗胡枝子中微量元素测定的理想方法。     

Anti-inflammatory alkaloids from the stems of Picrasma quassioides BENNET

During further chemical and biological investigations of Picrasma quassioides BENNET, four new bis-β-carboline alkaloids, quassidines E-H (1-4), and three new β-carboline alkaloids, canthin-16-one-14-butyric acid (5), 3-(1,1-dimethoxylmethyl)-β-carboline (6), and 6,12-dimethoxy-3-formyl-β-carboline (7), were isolated from its anti-inflammatory CHCl(3)-soluble fraction. Structures of new compounds were elucidated and characterized by MS and NMR analysis. A plausible biogenetic pathway for quassidine E (1), the first bis-β-carboline alkaloid in which a canthin-6-one moiety and a β-carboline moiety were connected together by a single carbon-carbon bond from the nature, was proposed. Quassidines E-G (1-3) showed potent inhibitory activity on the production of nitric oxide (NO), tumor necrosis factor α (TNF-α), or interleukin 6 (IL-6) in mouse monocyte-macrophage RAW264.7 cells stimulated by lipopolysaccharide (LPS). Analysis of anti-inflammatory activity of all β-carboline and bis-β-carboline alkaloids from P. quassioides showed that the carbonyl groups or double carbon-carbon bonds at C-14 for β-carbolines and C-14' for bis-β-carbolines were bioactive groups for their in vitro anti-inflammatory activity. Structure-activity relationship of these compounds on inhibitory activity of the three inflammatory cytokines was discussed.     

Synchronization and coherence resonance in chaotic neural networks

Synchronization and coherence of chaotic Morris--Lecar (ML) neural networks have been investigated by numerical methods. The synchronization of the neurons can be enhanced by increasing the number of the shortcuts, even though all neurons are chaotic when uncoupled. Moreover, the coherence of the neurons exhibits a non-monotonic dependence on the density of shortcuts. There is an optimal number of shortcuts at which the neurons' motion is most ordered, i.e. the order parameter (the characteristic correlation time) that is introduced to measure the coherence of the neurons has a maximum. These phenomena imply that stochastic shortcuts can tame spatiotemporal chaos. The effects of the coupling strength have also been studied. The value of the optimal number of shortcuts goes down as the coupling strength increases.     

Proangiogenic penibishexahydroxanthone A from the marine-derived fungus Penicillium sp. ZZ486A

Penibishexahydroxanthone A, a new hexahydroxanthone homodimer with a rare highly oxidized hexacyclic framework, was identified from the marine-derived Penicillium sp. ZZ486A. Its structure was determined by a combination of extensive NMR spectroscopical analyses, HRESIMS data, ECD calculation, and single crystal X-ray diffraction analysis. Penibishexahydroxanthone A showed in vivo activity in promoting angiogenesis in a dose-dependent manner by rescuing VRI-induced vascular insufficiency in zebrafish. This study is the first report of the proangiogenic activity of hexahydroxanthones.     

N型赝三元热压热电材料的微观结构和电学性能

通过熔炼/研磨技术和热压方法制备N型赝三元热压块体材料.通过SEM和XRD研究了由不同粒度粉末制备的热压块体材料的微观结构,在室温条件下测量了热压材料样品的电学性能.结果表明热压块体材料在微观结构和电学性能上存在各向异性,从而预示能够在增强材料机械强度的同时提高其热电性能.