Curvularin derivatives from the marine mangrove derived fungus Penicillium sumatrense MA-325.

Sumalarins D-G (1-4), four previously undescribed curvularin derivatives, along with two known related metabolites, curvularin (5) and dehydrocurvularin (6), were isolated and identified from the mangrove-derived fungus Penicillium sumatrense MA-325. Among them, sumalarin D (1) represents a unique example of curvularin derivative featuring a 5-methylfuran-2-yl-methyl group. Their structures were elucidated based on analysis of NMR and MS data as well as comparison of ECD spectra and quantum chemical calculations of NMR, and compound 1 was confirmed by X-ray crystallographic analysis. Compounds 1, 2, 5, and 6 are active against aquatic pathogenic bacteria Vibrio alginolyticus and V. harveyi with MIC values ranging from 4 to 64 µg/mL, while compound 6 is cytotoxic against tumor cell lines 5673, HCT 116, 786-O, and Hela with IC50 values of 3.5, 10.6, 10.9, and 14.9 µM, respectively.

Photocoupled Electroreduction of CO2 over Photosensitizer-Decorated Covalent Organic Frameworks.

Introducing an external visible-light field would be a promising strategy to improve the activity of the electrocatalytic CO2 reduction reaction (CO2RR), but it still remains a challenge due to the short excited-state lifetime of active sites. Herein, Ru(bpy)3Cl2 struts as powerful photosensitive donors were immobilized into the backbones of Co-porphyrin-based covalent organic frameworks (named Co-Bpy-COF-Rux, x is the molar ratio of Ru and Co species, x = 1/2 and 2/3) via coordination bonds, for the photo-coupled CO2RR to produce CO. The optimal Co-Bpy-COF-Ru1/2 displays a high CO Faradaic efficiency of 96.7% at -0.7 V vs reversible hydrogen electrode (RHE) and a CO partial current density of 16.27 mA cm-2 at -1.1 V vs RHE under the assistance of light, both of which were far surpassing the values observed in the dark. The significantly enhanced activity is mainly attributed to the incorporation of a Ru(bpy)3Cl2 donor with long excited-state lifetime and concomitantly giant built-in electric field in Co-Bpy-COF-Ru1/2, which efficiently accelerate the photo-induced electron transfer from Ru(bpy)3Cl2 to the cobalt-porphyrin under the external light. Thus, the cobalt-porphyrin active sites have a longer excited-state lifetime to lower the rate-determining steps' energy occurring during the actual photo-coupled electrocatalytic CO2RR process. This is the first work of porphyrin-based COFs for photo-coupled CO2RR, opening a new frontier for the construction of efficient photo-coupled electrocatalysts.

Atomically Precise Copper Nanoclusters for Highly Efficient Electroreduction of CO2 towards Hydrocarbons via Breaking the Coordination Symmetry of Cu Site.

We propose an effective highest occupied d-orbital modulation strategy engendered by breaking the coordination symmetry of sites in the atomically precise Cu nanocluster (NC) to switch the product of CO2 electroreduction from HCOOH/CO to higher-valued hydrocarbons. An atomically well-defined Cu6 NC with symmetry-broken Cu-S2 N1 active sites (named Cu6 (MBD)6 , MBD=2-mercaptobenzimidazole) was designed and synthesized by a judicious choice of ligand containing both S and N coordination atoms. Different from the previously reported high HCOOH selectivity of Cu NCs with Cu-S3 sites, the Cu6 (MBD)6 with Cu-S2 N1 coordination structure shows a high Faradaic efficiency toward hydrocarbons of 65.5 % at -1.4 V versus the reversible hydrogen electrode (including 42.5 % CH4 and 23 % C2 H4 ), with the hydrocarbons partial current density of -183.4 mA cm-2 . Theoretical calculations reveal that the symmetry-broken Cu-S2 N1 sites can rearrange the Cu 3d orbitals with d x 2 - y 2 ${d_{x^2 - y^2 } }$ as the highest occupied d-orbital, thus favoring the generation of key intermediate *COOH instead of *OCHO to favor *CO formation, followed by hydrogenation and/or C-C coupling to produce hydrocarbons. This is the first attempt to regulate the coordination mode of Cu atom in Cu NCs for hydrocarbons generation, and provides new inspiration for designing atomically precise NCs for efficient CO2 RR towards highly-valued products.

Oxepine-containing pyrazinopyrimidine alkaloids and quinolinone derivatives produced by Aspergillus versicolor AS-212, a deep-sea-derived endozoic fungus.

Four new oxepine-containing pyrazinopyrimidine alkaloids, versicoxepines A - D (1-4), two quinolinone alkaloid analogs including 3-hydroxy-6-methoxy-4-phenylquinolin-2(1H)-one (5) and 3-methoxy-6-hydroxy-4-phenylquinolin-2(1H)-one (6) which were new naturally occurring compounds, together with two known compounds (7 and 8) were isolated from Aspergillus versicolor AS-212, an endozoic fungus isolated from the deep-sea coral Hemicorallium cf. imperiale, which was collected from the Magellan Seamounts in the Western Pacific Ocean. Their structures were determined by extensive analysis of the spectroscopic and X-ray crystallographic data as well as by chiral HPLC analysis, ECD calculation, and DP4+ probability prediction. Structurally, versicoxepines B and C (2 and 3) represent the first example of a new oxepine-containing pyrazinopyrimidine alkaloid whose cyclic dipeptide moiety is composed of the same type of amino acid (Val or Ile). Compound 5 displayed antibacterial activity against aquatic pathogens, Vibrio harveyi and V. alginolyticus, with MICs of 8 µg/mL.

Diketopiperazine Alkaloids and Bisabolene Sesquiterpenoids from Aspergillus versicolor AS-212, an Endozoic Fungus Associated with Deep-Sea Coral of Magellan Seamounts.

Two new quinazolinone diketopiperazine alkaloids, including versicomide E (2) and cottoquinazoline H (4), together with ten known compounds (1, 3, and 5-12) were isolated and identified from Aspergillus versicolor AS-212, an endozoic fungus associated with the deep-sea coral Hemicorallium cf. imperiale, which was collected from the Magellan Seamounts. Their chemical structures were determined by an extensive interpretation of the spectroscopic and X-ray crystallographic data as well as specific rotation calculation, ECD calculation, and comparison of their ECD spectra. The absolute configurations of (-)-isoversicomide A (1) and cottoquinazoline A (3) were not assigned in the literature reports and were solved in the present work by single-crystal X-ray diffraction analysis. In the antibacterial assays, compound 3 exhibited antibacterial activity against aquatic pathogenic bacteria Aeromonas hydrophilia with an MIC value of 18.6 µM, while compounds 4 and 8 exhibited inhibitory effects against Vibrio harveyi and V. parahaemolyticus with MIC values ranging from 9.0 to 18.1 µM.

Boosting Electroreduction of CO2 over Cationic Covalent Organic Frameworks: Hydrogen Bonding Effects of Halogen Ions.

We present the first example of charged imidazolium functionalized porphyrin-based covalent organic framework (Co-iBFBim-COF-X) for electrocatalytic CO2 reduction reaction, where the free anions (e.g., F- , Cl- , Br- , and I- ) of imidazolium ions nearby the active Co sites can stabilize the key intermediate *COOH and inhibit hydrogen evolution reaction. Thus, Co-iBFBim-COF-X exhibits higher activity than the neutral Co-BFBim-COF, following the trend of F-

[Effects of litter addition on the dynamics of soil humic substances during freeze-thaw events in a subalpine forest.] / å†»èžçŽ¯å¢ƒä¸‹äºšé«˜å±±æ£®æž—å‡‹è½å¶æ·»åŠ å¯¹åœŸå£¤è æ®–è´¨åŠ¨æ€çš„å½±å“.

During soil formation, the accumulation of humic substances such as humic acid and fulvic acid is an important way to maintain soil fertility and nutrient cycling, which is regulated by soil substrate quality, litter, and environmental factors. In a laboratory incubation experiment, we exa-mined the effects of litter addition on soil humic substances accumulation in freeze-thaw environment by controlling the freeze-thaw cycles and litter additions in soils from the typical coniferous forest, mixed forest and broadleaved forest in a subalpine forest in western Sichuan. The freeze-thaw events significantly increased the content of humic substances in the coniferous forest soils but decreased those in the mixed forest soil and broadleaved forest soil. Litter addition had no significant effect on the content of soil humic substances. Freeze-thaw events increased the content of humic acid, with the net accumulation of humic acid following the order of mixed forest > coniferous forest > broad-leaved forest. Freeze-thaw events decreased the content of fulvic acid in the three forest soils during the early stage of incubation, and the degree of fulvic acid degradation was broadleaved forest > mixed forest > coniferous forest. Litter addition had no significant effect on the content of soil humic acid and fulvic acid. With prolonged incubation, the content of humic acid and fulvic acid in the three types of forest soils all declined. These results indicated that litter had effects on soil humic substances, which were related to soil substrate quality and affected by the duration of soil freeze-thaw events in winter.

Inhibitive mechanisms of Pim-3 affecting fulminant hepatic apoptosis / 中华肝脏病杂志

To investigate the mechanisms of serine/threonine kinase Pim-3 inhibition of fulminant hepatic apoptosis. Thirty-two rats were randomly divided into four groups (n = 8 each): normal controls (A); pretreatment with Ringer's solution (B), vector plasmid (C), or Pim-3 recombinant plasmid (D) by hydrodynamics-based procedure followed by intraperitoneal injections of lipopolysaccharide (LPS) and D-galactosamine (D-GalN) after one day. At 8 h after the LPS/D-GalN injections, liver tissues were collected from all groups of mice and analyzed for cell apoptosis by detecting caspase-3 activity (measured in relative fluorescence units, RFU). Changes in expression of relevant genes were determined by RT-PCR and Western blotting. Caspase-3 activity was induced in response to LPS/D-GalN injection. Pim-3-pretreated rats showed a lower level of caspase-3 activity than the Ringer's-pretreated or vector plasmid-pretreated rats [(141.7+/-13.7)RFU vs. (508.1+/-32.0) or (493.5+/-33.1) RFU; all P less than 0.01]. High expressions of the liver injury marker gene, iNOS, and the apoptosis-induced genes, p53 and Bax, were found after LPS/D-GalN challenge, and were suppressed by exogenous Pim-3 gene injection. In addition, exogenous Pim-3 gene injection induced high expression of the liver anti-apoptosis protein, Bcl-2, but had no effect on Bax protein expression. The Pim-3 gene can block fulminant hepatic apoptosis by affecting the expression of the iNOS liver injury gene and the p53, Bax and Bcl-2 apoptosis-related genes.

Microcalorimetric studies of perchlorate on heat production by hepatocytes and mitochondria isolated from Carassius auratus.

As a new threat to environment all through the world, perchlorate (ClO(4)(-)) was predominantly a thyrotoxin, and its toxic manifestations in non-thyroid were also documented. However, little is known about the effects of ClO(4)(-) on cell and organelle. Therefore, the present study was designed to investigate the effects of ClO(4)(-) on hepatocytes and mitochondria isolated from Carassius auratus from the direct viewpoint of energy by using the microcalorimetric method. The metabolic thermogenic curves of hepatocytes and mitochondria at 25°C were obtained. And the thermokinetic parameters, such as growth rate constant (k), inhibitory ratio (I), maximum thermal power (P(max)) and total thermal effect (Q(total)) have been calculated. The results indicated that the toxicity of ClO(4)(-) on hepatocytes was relevant to the concentration of ClO(4)(-). However, 10-100mgL(-1)ClO(4)(-) stimulated the metabolic activity of mitochondria and the toxicity of ClO(4)(-) on mitochondria only occurrenced when treated with higher concentration of ClO(4)(-). This study shown that mitochondria has a major impact on the metabolic thermogenic of hepatocytes, but not the only factor. Meanwhile, it demonstrated that microcalorimetry was a powerful tool for understanding biological processes and studying on the toxic action of environmental contaminants in cell or subcellular level.

Induction of oxidative stress and apoptosis by pentachlorophenol in primary cultures of Carassius carassius hepatocytes.

Pentachlorophenol (PCP) is a highly toxic contaminant of chlorophenols. Due to its slow and incomplete biodegradation, it can be found in surface, groundwater and in soils. To investigate the role of intracellular calcium and reactive oxygen species in apoptosis induced by PCP in cultured hepatocytes, the primary hepatocytes of Carassius carassius were incubated with different concentrations of PCP at 25 degrees C for 8 h in vitro. Apoptosis was detected by DNA laddering, caspase activation and flow cytometry. The results demonstrated that apoptosis was involved in the cytotoxic effect of PCP, and that PCP-induced apoptosis occurred in a dose-dependent manner. In addition, the induction of apoptosis by PCP was accompanied with Ca2+, Mg2+-ATPase activity decline, intracellular Ca2+ elevation, generation of intracellular reactive oxygen species (ROS), mitochondrial membrane potential (DeltaPsi(m)) disruption and ATP depletion. Concomitantly, there were dose-dependent increases in lipid peroxidation production (MDA) and decreases in glutathione (GSH). These investigations suggest that PCP-induces apoptosis in the cultured hepatocytes by affecting multiple targets, and suggest that [Ca2+]i increase and ROS generation may be involved in apoptosis induction by PCP.